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Concurrency | Multithreading examples in Java

 by   vijayontheweb Java Version: Current License: No License

 by   vijayontheweb Java Version: Current License: No License

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kandi X-RAY | Concurrency Summary

Concurrency is a Java library. Concurrency has no bugs, it has no vulnerabilities and it has low support. However Concurrency build file is not available. You can download it from GitHub.
Multithreading examples(with Presentation) in Java
Support
Support
Quality
Quality
Security
Security
License
License
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Reuse

kandi-support Support

  • Concurrency has a low active ecosystem.
  • It has 20 star(s) with 11 fork(s). There are 3 watchers for this library.
  • It had no major release in the last 12 months.
  • Concurrency has no issues reported. There are no pull requests.
  • It has a neutral sentiment in the developer community.
  • The latest version of Concurrency is current.
Concurrency Support
Best in #Java
Average in #Java
Concurrency Support
Best in #Java
Average in #Java

quality kandi Quality

  • Concurrency has 0 bugs and 0 code smells.
Concurrency Quality
Best in #Java
Average in #Java
Concurrency Quality
Best in #Java
Average in #Java

securitySecurity

  • Concurrency has no vulnerabilities reported, and its dependent libraries have no vulnerabilities reported.
  • Concurrency code analysis shows 0 unresolved vulnerabilities.
  • There are 0 security hotspots that need review.
Concurrency Security
Best in #Java
Average in #Java
Concurrency Security
Best in #Java
Average in #Java

license License

  • Concurrency does not have a standard license declared.
  • Check the repository for any license declaration and review the terms closely.
  • Without a license, all rights are reserved, and you cannot use the library in your applications.
Concurrency License
Best in #Java
Average in #Java
Concurrency License
Best in #Java
Average in #Java

buildReuse

  • Concurrency releases are not available. You will need to build from source code and install.
  • Concurrency has no build file. You will be need to create the build yourself to build the component from source.
Concurrency Reuse
Best in #Java
Average in #Java
Concurrency Reuse
Best in #Java
Average in #Java
Top functions reviewed by kandi - BETA

kandi has reviewed Concurrency and discovered the below as its top functions. This is intended to give you an instant insight into Concurrency implemented functionality, and help decide if they suit your requirements.

  • Displays the specified page URL .
    • Send an HTTP response to the remote server .
      • Time the given task runnable .
        • Handle a http request
          • Cleans up expired entries
            • Starts the crawling .
              • Compute and store the value in the cache .
                • Release the consumer .
                  • Crawl the directory .
                    • Fetches cache value from future .

                      Get all kandi verified functions for this library.

                      Get all kandi verified functions for this library.

                      Concurrency Key Features

                      Multithreading examples(with Presentation) in Java

                      PRECONDITION_FAILED: Delivery Acknowledge Timeout on Celery & RabbitMQ with Gevent and concurrency

                      copy iconCopydownload iconDownload
                      rabbitmq.conf: |
                        consumer_timeout = 31622400000
                      

                      Can another thread see an effectively immutable object in an inconsistent state if it is published with a volatile reference?

                      copy iconCopydownload iconDownload
                       --------------- T1 -------------
                       | write to num or this.num=num |
                       --------------------------------
                                       |
                                      \|/  (PO)
                       --------------- T1 -------------
                       |    write Wrapper instance    |
                       --------------------------------
                                       |
                                      \|/  (??)
                       --------------- T2 -------------
                       |    read Wrapper instance     |
                       --------------------------------
                                       |
                                      \|/  (PO)
                       --------------- T2 -------------
                       |      read num first time     |
                       --------------------------------
                                       |
                                      \|/  (PO)
                       --------------- T2 -------------
                       |      read num second time    |
                       --------------------------------
                      
                       --------------- T1 -------------
                       | write to num or this.num=num |
                       --------------------------------
                                       |
                                      \|/  (HB)
                       --------------- T1 -------------
                       |    write Wrapper instance    |
                       --------------------------------
                                       |
                                      \|/  (HB)
                       --------------- T2 -------------
                       |    read Wrapper instance     |
                       --------------------------------
                                       |
                                      \|/  (HB)
                       --------------- T2 -------------
                       |      read num first time     |
                       --------------------------------
                                       |
                                      \|/  (HB)
                       --------------- T2 -------------
                       |      read num second time    |
                       --------------------------------
                      
                       --------------- T1 -------------
                       | write to num or this.num=num |
                       --------------------------------
                                       |
                                      \|/  (PO)
                       --------------- T1 -------------
                       |    write Wrapper instance    |
                       --------------------------------
                                       |
                                      \|/  (??)
                       --------------- T2 -------------
                       |    read Wrapper instance     |
                       --------------------------------
                                       |
                                      \|/  (PO)
                       --------------- T2 -------------
                       |      read num first time     |
                       --------------------------------
                                       |
                                      \|/  (PO)
                       --------------- T2 -------------
                       |      read num second time    |
                       --------------------------------
                      
                       --------------- T1 -------------
                       | write to num or this.num=num |
                       --------------------------------
                                       |
                                      \|/  (HB)
                       --------------- T1 -------------
                       |    write Wrapper instance    |
                       --------------------------------
                                       |
                                      \|/  (HB)
                       --------------- T2 -------------
                       |    read Wrapper instance     |
                       --------------------------------
                                       |
                                      \|/  (HB)
                       --------------- T2 -------------
                       |      read num first time     |
                       --------------------------------
                                       |
                                      \|/  (HB)
                       --------------- T2 -------------
                       |      read num second time    |
                       --------------------------------
                      

                      Limit GitHub action workflow concurrency on push and pull_request?

                      copy iconCopydownload iconDownload
                      group: ${{ github.workflow }}-${{ github.ref }}
                      
                      group: ${{ github.workflow }}
                      
                      group: ${{ github.workflow }}-${{ github.ref }}
                      
                      group: ${{ github.workflow }}
                      
                      concurrency:
                        group: ${{ github.head_ref || github.ref_name }} 
                        cancel-in-progress: true
                      

                      How to limit concurrent http requests with Mono & Flux

                      copy iconCopydownload iconDownload
                      RateLimiter rateLimiter = RateLimiter.ofDefaults("name");
                      Mono.fromCallable(backendService::doSomething)
                          .transformDeferred(RateLimiterOperator.of(rateLimiter))
                      
                      
                      Mono<User> getById(int userId) { ... }
                      
                      Flux.just(1, 2, 3, 4).flatMap(client::getById, 2)
                      
                      

                      Generic requirement that Some: AsyncSequence is not throwing

                      copy iconCopydownload iconDownload
                      extension AsyncSequence where nothrow AsyncIterator {
                      
                      struct Foo<S: nothrow AsyncSequence>
                      
                      @rethrows public protocol AsyncSequence
                      
                      extension AsyncSequence where nothrow AsyncIterator {
                      
                      struct Foo<S: nothrow AsyncSequence>
                      
                      @rethrows public protocol AsyncSequence
                      
                      extension AsyncSequence where nothrow AsyncIterator {
                      
                      struct Foo<S: nothrow AsyncSequence>
                      
                      @rethrows public protocol AsyncSequence
                      

                      How to prevent actor reentrancy resulting in duplicative requests?

                      copy iconCopydownload iconDownload
                      actor ImageDownloader {
                          private var cache: [URL: Image] = [:]
                          private var tasks: [URL: Task<Image, Error>] = [:]
                      
                          func image(from url: URL) async throws -> Image {
                              if let image = try await tasks[url]?.value {
                                  print("found request")
                                  return image
                              }
                      
                              if let cached = cache[url] {
                                  print("found cached")
                                  return cached
                              }
                      
                              let task = Task {
                                  try await download(from: url)
                              }
                      
                              tasks[url] = task
                              defer { tasks[url] = nil }
                      
                              let image = try await task.value
                              cache[url] = image
                      
                              return image
                          }
                      
                          private func download(from url: URL) async throws -> Image {
                              let (data, response) = try await URLSession.shared.data(from: url)
                              guard
                                  let response = response as? HTTPURLResponse,
                                  200 ..< 300 ~= response.statusCode,
                                  let image = Image(data: data)
                              else {
                                  throw URLError(.badServerResponse)
                              }
                              return image
                          }
                      }
                      
                      actor ImageDownloader {
                          private enum ImageStatus {
                              case downloading(_ task: Task<UIImage, Error>)
                              case downloaded(_ image: UIImage)
                          }
                          
                          private var cache: [URL: ImageStatus] = [:]
                          
                          func image(from url: URL) async throws -> UIImage {
                              if let imageStatus = cache[url] {
                                  switch imageStatus {
                                  case .downloading(let task):
                                      return try await task.value
                                  case .downloaded(let image):
                                      return image
                                  }
                              }
                              
                              let task = Task {
                                  try await downloadImage(url: url)
                              }
                              
                              cache[url] = .downloading(task)
                              
                              do {
                                  let image = try await task.value
                                  cache[url] = .downloaded(image)
                                  return image
                              } catch {
                                  // If an error occurs, we will evict the URL from the cache
                                  // and rethrow the original error.
                                  cache.removeValue(forKey: url)
                                  throw error
                              }
                          }
                          
                          private func downloadImage(url: URL) async throws -> UIImage {
                              let imageRequest = URLRequest(url: url)
                              let (data, imageResponse) = try await URLSession.shared.data(for: imageRequest)
                              guard let image = UIImage(data: data), (imageResponse as? HTTPURLResponse)?.statusCode == 200 else {
                                  throw ImageDownloadError.badImage
                              }
                              return image
                          }
                      }
                      
                      actor ImageDownloader {
                      
                          private enum CacheEntry {
                              case inProgress(Task<Image, Error>)
                              case ready(Image)
                          }
                      
                          private var cache: [URL: CacheEntry] = [:]
                      
                          func image(from url: URL) async throws -> Image? {
                              if let cached = cache[url] {
                                  switch cached {
                                  case .ready(let image):
                                      return image
                                  case .inProgress(let task):
                                      return try await task.value
                                  }
                              }
                      
                              let task = Task {
                                  try await downloadImage(from: url)
                              }
                      
                              cache[url] = .inProgress(task)
                      
                              do {
                                  let image = try await task.value
                                  cache[url] = .ready(image)
                                  return image
                              } catch {
                                  cache[url] = nil
                                  throw error
                              }
                          }
                      }
                      

                      FastAPI - Pydantic - Value Error Raises Internal Server Error

                      copy iconCopydownload iconDownload
                      from fastapi import FastAPI, Request
                      from fastapi.responses import JSONResponse
                      
                      
                      @app.exception_handler(ValueError)
                      async def value_error_exception_handler(request: Request, exc: ValueError):
                          return JSONResponse(
                              status_code=400,
                              content={"message": str(exc)},
                          )
                      
                      {
                          "message": "Value Must be within range (0,1000000)"
                      }
                      
                      from fastapi import FastAPI, Request
                      from fastapi.responses import JSONResponse
                      
                      
                      @app.exception_handler(ValueError)
                      async def value_error_exception_handler(request: Request, exc: ValueError):
                          return JSONResponse(
                              status_code=400,
                              content={"message": str(exc)},
                          )
                      
                      {
                          "message": "Value Must be within range (0,1000000)"
                      }
                      
                      from fastapi import Depends, FastAPI, Request, status
                      from fastapi.exceptions import RequestValidationError
                      from fastapi.exception_handlers import request_validation_exception_handler
                      from fastapi.responses import JSONResponse
                      from pydantic import BaseModel, conint
                      
                      class RankInput(BaseModel):
                          # Constrained integer, must be greater that or equal to 0
                          # and less than or equal to 1 million.
                          rank: conint(ge=0, le=1_000_000)
                      
                      async def rank_out_of_bound_handler(request: Request, exc: RequestValidationError):
                      
                          validation_errors = exc.errors()
                          for err in validation_errors:
                              # You could check for other things here as well, e.g. the error type.
                              if "rank" in err["loc"]:
                                  return JSONResponse(
                                      status_code=status.HTTP_400_BAD_REQUEST,
                                      content={"message": "Rank must be in range [0, 1000000]."}
                                  )
                      
                          # Default response in every other case.
                          return await request_validation_exception_handler(request, exc)
                      
                      def get_info_by_rank(rank):
                          return rank
                      
                      
                      app = FastAPI(
                          exception_handlers={RequestValidationError: rank_out_of_bound_handler},
                      )
                      
                      @app.get('/rank/{rank}')
                      async def get_rank(value: RankInput = Depends()):
                          result = get_info_by_rank(value.rank)
                          return result
                      
                      $ curl -i "http://127.0.0.1:8000/rank/1"
                      HTTP/1.1 200 OK
                      date: Sat, 28 Aug 2021 20:47:58 GMT
                      server: uvicorn
                      content-length: 1
                      content-type: application/json
                      
                      1
                      
                      $  curl -i "http://127.0.0.1:8000/rank/-1"
                      HTTP/1.1 400 Bad Request
                      date: Sat, 28 Aug 2021 20:48:24 GMT
                      server: uvicorn
                      content-length: 49
                      content-type: application/json
                      
                      {"message":"Rank must be in range [0, 1000000]."}
                      
                      $ curl -i "http://127.0.0.1:8000/rank/1000001"
                      HTTP/1.1 400 Bad Request
                      date: Sat, 28 Aug 2021 20:48:51 GMT
                      server: uvicorn
                      content-length: 49
                      content-type: application/json
                      
                      {"message":"Rank must be in range [0, 1000000]."}
                      
                      @app.get('/other-rank/{rank}')
                      async def get_other_rank(value: RankInput = Depends()):
                          result = get_info_by_rank(value.rank)
                          return result
                      
                      $ curl -i "http://127.0.0.1:8000/other-rank/-1"
                      HTTP/1.1 400 Bad Request
                      date: Sat, 28 Aug 2021 20:54:16 GMT
                      server: uvicorn
                      content-length: 49
                      content-type: application/json
                      
                      {"message":"Rank must be in range [0, 1000000]."}
                      
                      from fastapi import Depends, FastAPI, Request, status
                      from fastapi.exceptions import RequestValidationError
                      from fastapi.exception_handlers import request_validation_exception_handler
                      from fastapi.responses import JSONResponse
                      from pydantic import BaseModel, conint
                      
                      class RankInput(BaseModel):
                          # Constrained integer, must be greater that or equal to 0
                          # and less than or equal to 1 million.
                          rank: conint(ge=0, le=1_000_000)
                      
                      async def rank_out_of_bound_handler(request: Request, exc: RequestValidationError):
                      
                          validation_errors = exc.errors()
                          for err in validation_errors:
                              # You could check for other things here as well, e.g. the error type.
                              if "rank" in err["loc"]:
                                  return JSONResponse(
                                      status_code=status.HTTP_400_BAD_REQUEST,
                                      content={"message": "Rank must be in range [0, 1000000]."}
                                  )
                      
                          # Default response in every other case.
                          return await request_validation_exception_handler(request, exc)
                      
                      def get_info_by_rank(rank):
                          return rank
                      
                      
                      app = FastAPI(
                          exception_handlers={RequestValidationError: rank_out_of_bound_handler},
                      )
                      
                      @app.get('/rank/{rank}')
                      async def get_rank(value: RankInput = Depends()):
                          result = get_info_by_rank(value.rank)
                          return result
                      
                      $ curl -i "http://127.0.0.1:8000/rank/1"
                      HTTP/1.1 200 OK
                      date: Sat, 28 Aug 2021 20:47:58 GMT
                      server: uvicorn
                      content-length: 1
                      content-type: application/json
                      
                      1
                      
                      $  curl -i "http://127.0.0.1:8000/rank/-1"
                      HTTP/1.1 400 Bad Request
                      date: Sat, 28 Aug 2021 20:48:24 GMT
                      server: uvicorn
                      content-length: 49
                      content-type: application/json
                      
                      {"message":"Rank must be in range [0, 1000000]."}
                      
                      $ curl -i "http://127.0.0.1:8000/rank/1000001"
                      HTTP/1.1 400 Bad Request
                      date: Sat, 28 Aug 2021 20:48:51 GMT
                      server: uvicorn
                      content-length: 49
                      content-type: application/json
                      
                      {"message":"Rank must be in range [0, 1000000]."}
                      
                      @app.get('/other-rank/{rank}')
                      async def get_other_rank(value: RankInput = Depends()):
                          result = get_info_by_rank(value.rank)
                          return result
                      
                      $ curl -i "http://127.0.0.1:8000/other-rank/-1"
                      HTTP/1.1 400 Bad Request
                      date: Sat, 28 Aug 2021 20:54:16 GMT
                      server: uvicorn
                      content-length: 49
                      content-type: application/json
                      
                      {"message":"Rank must be in range [0, 1000000]."}
                      
                      from fastapi import Depends, FastAPI, Request, status
                      from fastapi.exceptions import RequestValidationError
                      from fastapi.exception_handlers import request_validation_exception_handler
                      from fastapi.responses import JSONResponse
                      from pydantic import BaseModel, conint
                      
                      class RankInput(BaseModel):
                          # Constrained integer, must be greater that or equal to 0
                          # and less than or equal to 1 million.
                          rank: conint(ge=0, le=1_000_000)
                      
                      async def rank_out_of_bound_handler(request: Request, exc: RequestValidationError):
                      
                          validation_errors = exc.errors()
                          for err in validation_errors:
                              # You could check for other things here as well, e.g. the error type.
                              if "rank" in err["loc"]:
                                  return JSONResponse(
                                      status_code=status.HTTP_400_BAD_REQUEST,
                                      content={"message": "Rank must be in range [0, 1000000]."}
                                  )
                      
                          # Default response in every other case.
                          return await request_validation_exception_handler(request, exc)
                      
                      def get_info_by_rank(rank):
                          return rank
                      
                      
                      app = FastAPI(
                          exception_handlers={RequestValidationError: rank_out_of_bound_handler},
                      )
                      
                      @app.get('/rank/{rank}')
                      async def get_rank(value: RankInput = Depends()):
                          result = get_info_by_rank(value.rank)
                          return result
                      
                      $ curl -i "http://127.0.0.1:8000/rank/1"
                      HTTP/1.1 200 OK
                      date: Sat, 28 Aug 2021 20:47:58 GMT
                      server: uvicorn
                      content-length: 1
                      content-type: application/json
                      
                      1
                      
                      $  curl -i "http://127.0.0.1:8000/rank/-1"
                      HTTP/1.1 400 Bad Request
                      date: Sat, 28 Aug 2021 20:48:24 GMT
                      server: uvicorn
                      content-length: 49
                      content-type: application/json
                      
                      {"message":"Rank must be in range [0, 1000000]."}
                      
                      $ curl -i "http://127.0.0.1:8000/rank/1000001"
                      HTTP/1.1 400 Bad Request
                      date: Sat, 28 Aug 2021 20:48:51 GMT
                      server: uvicorn
                      content-length: 49
                      content-type: application/json
                      
                      {"message":"Rank must be in range [0, 1000000]."}
                      
                      @app.get('/other-rank/{rank}')
                      async def get_other_rank(value: RankInput = Depends()):
                          result = get_info_by_rank(value.rank)
                          return result
                      
                      $ curl -i "http://127.0.0.1:8000/other-rank/-1"
                      HTTP/1.1 400 Bad Request
                      date: Sat, 28 Aug 2021 20:54:16 GMT
                      server: uvicorn
                      content-length: 49
                      content-type: application/json
                      
                      {"message":"Rank must be in range [0, 1000000]."}
                      
                      from fastapi import Depends, FastAPI, Request, status
                      from fastapi.exceptions import RequestValidationError
                      from fastapi.exception_handlers import request_validation_exception_handler
                      from fastapi.responses import JSONResponse
                      from pydantic import BaseModel, conint
                      
                      class RankInput(BaseModel):
                          # Constrained integer, must be greater that or equal to 0
                          # and less than or equal to 1 million.
                          rank: conint(ge=0, le=1_000_000)
                      
                      async def rank_out_of_bound_handler(request: Request, exc: RequestValidationError):
                      
                          validation_errors = exc.errors()
                          for err in validation_errors:
                              # You could check for other things here as well, e.g. the error type.
                              if "rank" in err["loc"]:
                                  return JSONResponse(
                                      status_code=status.HTTP_400_BAD_REQUEST,
                                      content={"message": "Rank must be in range [0, 1000000]."}
                                  )
                      
                          # Default response in every other case.
                          return await request_validation_exception_handler(request, exc)
                      
                      def get_info_by_rank(rank):
                          return rank
                      
                      
                      app = FastAPI(
                          exception_handlers={RequestValidationError: rank_out_of_bound_handler},
                      )
                      
                      @app.get('/rank/{rank}')
                      async def get_rank(value: RankInput = Depends()):
                          result = get_info_by_rank(value.rank)
                          return result
                      
                      $ curl -i "http://127.0.0.1:8000/rank/1"
                      HTTP/1.1 200 OK
                      date: Sat, 28 Aug 2021 20:47:58 GMT
                      server: uvicorn
                      content-length: 1
                      content-type: application/json
                      
                      1
                      
                      $  curl -i "http://127.0.0.1:8000/rank/-1"
                      HTTP/1.1 400 Bad Request
                      date: Sat, 28 Aug 2021 20:48:24 GMT
                      server: uvicorn
                      content-length: 49
                      content-type: application/json
                      
                      {"message":"Rank must be in range [0, 1000000]."}
                      
                      $ curl -i "http://127.0.0.1:8000/rank/1000001"
                      HTTP/1.1 400 Bad Request
                      date: Sat, 28 Aug 2021 20:48:51 GMT
                      server: uvicorn
                      content-length: 49
                      content-type: application/json
                      
                      {"message":"Rank must be in range [0, 1000000]."}
                      
                      @app.get('/other-rank/{rank}')
                      async def get_other_rank(value: RankInput = Depends()):
                          result = get_info_by_rank(value.rank)
                          return result
                      
                      $ curl -i "http://127.0.0.1:8000/other-rank/-1"
                      HTTP/1.1 400 Bad Request
                      date: Sat, 28 Aug 2021 20:54:16 GMT
                      server: uvicorn
                      content-length: 49
                      content-type: application/json
                      
                      {"message":"Rank must be in range [0, 1000000]."}
                      
                      from fastapi import Depends, FastAPI, Request, status
                      from fastapi.exceptions import RequestValidationError
                      from fastapi.exception_handlers import request_validation_exception_handler
                      from fastapi.responses import JSONResponse
                      from pydantic import BaseModel, conint
                      
                      class RankInput(BaseModel):
                          # Constrained integer, must be greater that or equal to 0
                          # and less than or equal to 1 million.
                          rank: conint(ge=0, le=1_000_000)
                      
                      async def rank_out_of_bound_handler(request: Request, exc: RequestValidationError):
                      
                          validation_errors = exc.errors()
                          for err in validation_errors:
                              # You could check for other things here as well, e.g. the error type.
                              if "rank" in err["loc"]:
                                  return JSONResponse(
                                      status_code=status.HTTP_400_BAD_REQUEST,
                                      content={"message": "Rank must be in range [0, 1000000]."}
                                  )
                      
                          # Default response in every other case.
                          return await request_validation_exception_handler(request, exc)
                      
                      def get_info_by_rank(rank):
                          return rank
                      
                      
                      app = FastAPI(
                          exception_handlers={RequestValidationError: rank_out_of_bound_handler},
                      )
                      
                      @app.get('/rank/{rank}')
                      async def get_rank(value: RankInput = Depends()):
                          result = get_info_by_rank(value.rank)
                          return result
                      
                      $ curl -i "http://127.0.0.1:8000/rank/1"
                      HTTP/1.1 200 OK
                      date: Sat, 28 Aug 2021 20:47:58 GMT
                      server: uvicorn
                      content-length: 1
                      content-type: application/json
                      
                      1
                      
                      $  curl -i "http://127.0.0.1:8000/rank/-1"
                      HTTP/1.1 400 Bad Request
                      date: Sat, 28 Aug 2021 20:48:24 GMT
                      server: uvicorn
                      content-length: 49
                      content-type: application/json
                      
                      {"message":"Rank must be in range [0, 1000000]."}
                      
                      $ curl -i "http://127.0.0.1:8000/rank/1000001"
                      HTTP/1.1 400 Bad Request
                      date: Sat, 28 Aug 2021 20:48:51 GMT
                      server: uvicorn
                      content-length: 49
                      content-type: application/json
                      
                      {"message":"Rank must be in range [0, 1000000]."}
                      
                      @app.get('/other-rank/{rank}')
                      async def get_other_rank(value: RankInput = Depends()):
                          result = get_info_by_rank(value.rank)
                          return result
                      
                      $ curl -i "http://127.0.0.1:8000/other-rank/-1"
                      HTTP/1.1 400 Bad Request
                      date: Sat, 28 Aug 2021 20:54:16 GMT
                      server: uvicorn
                      content-length: 49
                      content-type: application/json
                      
                      {"message":"Rank must be in range [0, 1000000]."}
                      
                      from fastapi import Depends, FastAPI, Request, status
                      from fastapi.exceptions import RequestValidationError
                      from fastapi.exception_handlers import request_validation_exception_handler
                      from fastapi.responses import JSONResponse
                      from pydantic import BaseModel, conint
                      
                      class RankInput(BaseModel):
                          # Constrained integer, must be greater that or equal to 0
                          # and less than or equal to 1 million.
                          rank: conint(ge=0, le=1_000_000)
                      
                      async def rank_out_of_bound_handler(request: Request, exc: RequestValidationError):
                      
                          validation_errors = exc.errors()
                          for err in validation_errors:
                              # You could check for other things here as well, e.g. the error type.
                              if "rank" in err["loc"]:
                                  return JSONResponse(
                                      status_code=status.HTTP_400_BAD_REQUEST,
                                      content={"message": "Rank must be in range [0, 1000000]."}
                                  )
                      
                          # Default response in every other case.
                          return await request_validation_exception_handler(request, exc)
                      
                      def get_info_by_rank(rank):
                          return rank
                      
                      
                      app = FastAPI(
                          exception_handlers={RequestValidationError: rank_out_of_bound_handler},
                      )
                      
                      @app.get('/rank/{rank}')
                      async def get_rank(value: RankInput = Depends()):
                          result = get_info_by_rank(value.rank)
                          return result
                      
                      $ curl -i "http://127.0.0.1:8000/rank/1"
                      HTTP/1.1 200 OK
                      date: Sat, 28 Aug 2021 20:47:58 GMT
                      server: uvicorn
                      content-length: 1
                      content-type: application/json
                      
                      1
                      
                      $  curl -i "http://127.0.0.1:8000/rank/-1"
                      HTTP/1.1 400 Bad Request
                      date: Sat, 28 Aug 2021 20:48:24 GMT
                      server: uvicorn
                      content-length: 49
                      content-type: application/json
                      
                      {"message":"Rank must be in range [0, 1000000]."}
                      
                      $ curl -i "http://127.0.0.1:8000/rank/1000001"
                      HTTP/1.1 400 Bad Request
                      date: Sat, 28 Aug 2021 20:48:51 GMT
                      server: uvicorn
                      content-length: 49
                      content-type: application/json
                      
                      {"message":"Rank must be in range [0, 1000000]."}
                      
                      @app.get('/other-rank/{rank}')
                      async def get_other_rank(value: RankInput = Depends()):
                          result = get_info_by_rank(value.rank)
                          return result
                      
                      $ curl -i "http://127.0.0.1:8000/other-rank/-1"
                      HTTP/1.1 400 Bad Request
                      date: Sat, 28 Aug 2021 20:54:16 GMT
                      server: uvicorn
                      content-length: 49
                      content-type: application/json
                      
                      {"message":"Rank must be in range [0, 1000000]."}
                      

                      Why do I see an error about 'data(for:delegate:) is only available on iOS 15.0+' even though modern concurrency is backward compatible

                      copy iconCopydownload iconDownload
                      @available(iOS, deprecated: 15.0, message: "Use the built-in API instead")
                      extension URLSession {
                          func data(from url: URL) async throws -> (Data, URLResponse) {
                               try await withCheckedThrowingContinuation { continuation in
                                  let task = self.dataTask(with: url) { data, response, error in
                                       guard let data = data, let response = response else {
                                           let error = error ?? URLError(.badServerResponse)
                                           return continuation.resume(throwing: error)
                                       }
                      
                                       continuation.resume(returning: (data, response))
                                   }
                      
                                   task.resume()
                              }
                          }
                      }
                      

                      Running two Tensorflow trainings in parallel using joblib and dask

                      copy iconCopydownload iconDownload
                      client = Client(address)
                      
                      client = Client(scheduler_file=the_file_you_wrote)
                      
                      client = Client(address)
                      
                      client = Client(scheduler_file=the_file_you_wrote)
                      

                      How promises inside for loop are working?

                      copy iconCopydownload iconDownload
                      let iter = async (value) => {
                        // randomly delay each calculation to 1, 2 or 3 seconds
                        return new Promise(resolve => setTimeout(resolve, [1000, 2000, 3000][Math.floor(Math.random() * 3)], value * 2))
                      }
                      
                      promiseMapLimit(testArray, 20, iter).then((result) =>
                        console.log(result)
                      );
                      
                      if (poolLimit <= array.length) {
                            const e = p.then(() => {
                              executing.splice(executing.indexOf(e), 1);
                      // logging what is left
                               console.log({l: executing.length})
                               });
                            executing.push(e);
                            if (executing.length >= poolLimit) {
                              await Promise.race(executing);
                            }
                          }
                      
                      let iter = async (value) => {
                        // randomly delay each calculation to 1, 2 or 3 seconds
                        return new Promise(resolve => setTimeout(resolve, [1000, 2000, 3000][Math.floor(Math.random() * 3)], value * 2))
                      }
                      
                      promiseMapLimit(testArray, 20, iter).then((result) =>
                        console.log(result)
                      );
                      
                      if (poolLimit <= array.length) {
                            const e = p.then(() => {
                              executing.splice(executing.indexOf(e), 1);
                      // logging what is left
                               console.log({l: executing.length})
                               });
                            executing.push(e);
                            if (executing.length >= poolLimit) {
                              await Promise.race(executing);
                            }
                          }
                      
                      async function promiseMapLimit(
                          array,
                          poolLimit,
                          iteratorFn,
                        ) {
                      
                          // array for storing results / ResultPromises
                          const ret = [];
                      
                          // array holding currently executed functions!.
                          const executing = [];
                      
                          // iterate over array
                          for (const item of array) {
                      
                            // Create a new Promise which is instantly resolved!.
                            // this is syntactic sougar and could also be written as:
                            // const p = new Promise((res, rej) => iteratorFn(item, array).then(res))
                            // but with this used version, it also would allow the iteratorFn to be NON ASYNC 
                            const p = Promise.resolve().then(
                      
                              // since it is resolved immediatly, this code block will be executed
                              // not immediatly but almost immediatly. (few mikroseconds delay..)
                              // Under the hoods, js always adds up all functions into a queue. 
                              // So this function body will for example be executed after the `ret.push(p)` !! 
                                () =>  iteratorFn(item, array)
                              );
                      
                            // store the created promise in the results array anyways!!
                            ret.push(p);
                        
                      
                            // If the array holds less elements than poolLimit then nothing has to be done here and
                            // all elements can directly be executed.
                            if (poolLimit <= array.length) {
                      
                              // if we get in here, it says that there are more elements in the array than allowed by 
                              // poolLimit. 
                      
                              // This line adds a success handler to the promise. It basically 
                              // removes itself from the executing array at the point it finishes!.
                              const e = p.then(() =>
                      
                                  // here you see, it searches for itself, and removes itself from the array using splice!.
                                  executing.splice(executing.indexOf(e), 1)
                              );
                      
                      
                              // Add the promise to the currently executing ones. 
                              // Note that this following line is executed before the "executing.splice(executing.indexOf(e), 1)"
                              executing.push(e);
                      
                              // And the final, smart part!.
                              // If in the executing array are less elements than maximum allowed,
                              // do nothing!
                              if (executing.length >= poolLimit) {
                                  // we got here, so the allowed size of executing queue is smaller than array.length . 
                                  // Promise.race() waits for the first promise to resolve in a given array
                                  // So at the moment any promise is resolved, the execution will go on and not before!.
                                  // Since the promises remove themselves from the executing array we know 1 
                                  // promise is now finished and the executing holds a space!.
                                await Promise.race(executing);
                              }
                            }
                          }
                        
                      
                          // since all promises were looped and added to results array it's now 
                          // possible to await them all!.
                          return Promise.all(ret);
                        }
                      
                      if (poolLimit <= array.length) {
                        const e = p.then(() => executing.splice(executing.indexOf(e), 1));
                        executing.push(e);
                        if (executing.length >= poolLimit) {
                          await Promise.race(executing);
                        }
                      }
                      
                      const limiter = async (array, limit) => {
                        const promises = []
                        const executing = []
                      
                        while (array.length !== promises.length) {
                          if (executing.length <= limit) {
                            executing.push(/* new promise here */ ...then(example => {
                              promises.push(example)
                              // splice execution array
                            }))
                          }
                        }
                      
                        return Promise.all(promises)
                      }
                      
                      if (poolLimit <= array.length) {
                        const e = p.then(() => executing.splice(executing.indexOf(e), 1));
                        executing.push(e);
                        if (executing.length >= poolLimit) {
                          await Promise.race(executing);
                        }
                      }
                      
                      const limiter = async (array, limit) => {
                        const promises = []
                        const executing = []
                      
                        while (array.length !== promises.length) {
                          if (executing.length <= limit) {
                            executing.push(/* new promise here */ ...then(example => {
                              promises.push(example)
                              // splice execution array
                            }))
                          }
                        }
                      
                        return Promise.all(promises)
                      }
                      
                      PromiseID  | Start                 End |
                      0          [====]
                      1          [==]
                      2          [======]
                      3             [==========]
                      4               [====]
                      5                 [================]
                      6                    [==]
                      7                       [====]
                      8                        [======]
                      9                            [========]
                      
                      // Create the utility sleep function
                      const sleep = x => new Promise(res => setTimeout(res, x))
                      
                      async function promiseMapLimit(array, poolLimit, iteratorFn) {
                        const ret = [];
                        const executing = [];
                        for (const item of array) {
                          const p = Promise.resolve().then(() => iteratorFn(item, array));
                          ret.push(p);
                      
                          console.log(ret.length)
                          if (poolLimit <= array.length) {
                            const e = p.then(() => executing.splice(executing.indexOf(e), 1));
                            executing.push(e);
                            if (executing.length >= poolLimit) {
                              console.log(`Running batch of ${executing.length} promises.`);
                              await Promise.race(executing);
                              // As ssoon one of the promise finishes, we continue the loop.
                              console.log("Resolved one promise.")
                            }
                          }
                        }
                      
                        return Promise.all(ret);
                      }
                      
                      const testArray = Array.from(Array(100).keys());
                      
                      promiseMapLimit(testArray, 20, async (value) => {
                        // Log
                        console.log(`Computing iterator fn for ${value}`)
                        await sleep(3000 + Math.random() * 3000);
                        return value * 2
                      }).then((result) =>
                        console.log(result)
                      );
                      PromiseID  | Start                 End |
                      0          [====]
                      1          [==]
                      2          [======]
                      3             [==========]
                      4               [====]
                      5                 [================]
                      6                    [==]
                      7                       [====]
                      8                        [======]
                      9                            [========]
                      
                      // Create the utility sleep function
                      const sleep = x => new Promise(res => setTimeout(res, x))
                      
                      async function promiseMapLimit(array, poolLimit, iteratorFn) {
                        const ret = [];
                        const executing = [];
                        for (const item of array) {
                          const p = Promise.resolve().then(() => iteratorFn(item, array));
                          ret.push(p);
                      
                          console.log(ret.length)
                          if (poolLimit <= array.length) {
                            const e = p.then(() => executing.splice(executing.indexOf(e), 1));
                            executing.push(e);
                            if (executing.length >= poolLimit) {
                              console.log(`Running batch of ${executing.length} promises.`);
                              await Promise.race(executing);
                              // As ssoon one of the promise finishes, we continue the loop.
                              console.log("Resolved one promise.")
                            }
                          }
                        }
                      
                        return Promise.all(ret);
                      }
                      
                      const testArray = Array.from(Array(100).keys());
                      
                      promiseMapLimit(testArray, 20, async (value) => {
                        // Log
                        console.log(`Computing iterator fn for ${value}`)
                        await sleep(3000 + Math.random() * 3000);
                        return value * 2
                      }).then((result) =>
                        console.log(result)
                      );
                      async function promiseMapLimit(
                        array,
                        poolLimit,
                        iteratorFn,
                      ) {
                        const ret = [];
                        const executing = [];
                        for (const item of array) {
                          const p = Promise.resolve().then(() => iteratorFn(item, array));
                          ret.push(p);
                      
                          if (poolLimit <= array.length) {
                            const e = p.then(() => executing.splice(executing.indexOf(e), 1));
                            executing.push(e);
                            if (executing.length >= poolLimit) {
                              await Promise.race(executing);
                            }
                          }
                        }
                      
                        return Promise.all(ret);
                      }
                      
                      promiseMapLimit([1, 2, 3], 1, async function (i) => { return 2 * i });
                      
                      const e = p.then(() => {
                          1. Keep e as closure variable for later, for when the promise does get resolved in Promise.race line
                          2. find that e in executing array
                          3. Remove it
                      });
                      
                      async function promiseMapLimit(
                        array,
                        poolLimit,
                        iteratorFn,
                      ) {
                        const ret = [];
                        const executing = [];
                        for (const item of array) {
                          const p = Promise.resolve().then(() => iteratorFn(item, array));
                          ret.push(p);
                        }
                        if (poolLimit > array.length) {
                          // if poolLimit and greater that array just resolve all the promises and no need to worry of concurrency
                          return Promise.all(ret);       
                        }
                        for (const p of ret) {
                            // Add self remove logic to each promise element
                            const e = p.then(() => executing.splice(executing.indexOf(e), 1));
                            // Put the promise element in execution queue
                            executing.push(e);
                            // Whenever the execution ques is full wait for execution of the promises
                            // Promise.race awaits for all the promises to finish execution
                            // And because of the self removal logic execution queue also becomes empty
                            if (executing.length >= poolLimit) {
                              await Promise.race(executing);
                            }
                        }
                        // Promise.all will take care of all the promises remaining in the last batch for which await Promise.race(executing); was not executed.
                        return Promise.all(ret);
                      }
                      
                      async function promiseMapLimit(
                        array,
                        poolLimit,
                        iteratorFn,
                      ) {
                        const ret = [];
                        const executing = [];
                        for (const item of array) {
                          const p = Promise.resolve().then(() => iteratorFn(item, array));
                          ret.push(p);
                      
                          if (poolLimit <= array.length) {
                            const e = p.then(() => executing.splice(executing.indexOf(e), 1));
                            executing.push(e);
                            if (executing.length >= poolLimit) {
                              await Promise.race(executing);
                            }
                          }
                        }
                      
                        return Promise.all(ret);
                      }
                      
                      promiseMapLimit([1, 2, 3], 1, async function (i) => { return 2 * i });
                      
                      const e = p.then(() => {
                          1. Keep e as closure variable for later, for when the promise does get resolved in Promise.race line
                          2. find that e in executing array
                          3. Remove it
                      });
                      
                      async function promiseMapLimit(
                        array,
                        poolLimit,
                        iteratorFn,
                      ) {
                        const ret = [];
                        const executing = [];
                        for (const item of array) {
                          const p = Promise.resolve().then(() => iteratorFn(item, array));
                          ret.push(p);
                        }
                        if (poolLimit > array.length) {
                          // if poolLimit and greater that array just resolve all the promises and no need to worry of concurrency
                          return Promise.all(ret);       
                        }
                        for (const p of ret) {
                            // Add self remove logic to each promise element
                            const e = p.then(() => executing.splice(executing.indexOf(e), 1));
                            // Put the promise element in execution queue
                            executing.push(e);
                            // Whenever the execution ques is full wait for execution of the promises
                            // Promise.race awaits for all the promises to finish execution
                            // And because of the self removal logic execution queue also becomes empty
                            if (executing.length >= poolLimit) {
                              await Promise.race(executing);
                            }
                        }
                        // Promise.all will take care of all the promises remaining in the last batch for which await Promise.race(executing); was not executed.
                        return Promise.all(ret);
                      }
                      
                      async function promiseMapLimit(
                        array,
                        poolLimit,
                        iteratorFn,
                      ) {
                        const ret = [];
                        const executing = [];
                        for (const item of array) {
                          const p = Promise.resolve().then(() => iteratorFn(item, array));
                          ret.push(p);
                      
                          if (poolLimit <= array.length) {
                            const e = p.then(() => executing.splice(executing.indexOf(e), 1));
                            executing.push(e);
                            if (executing.length >= poolLimit) {
                              await Promise.race(executing);
                            }
                          }
                        }
                      
                        return Promise.all(ret);
                      }
                      
                      promiseMapLimit([1, 2, 3], 1, async function (i) => { return 2 * i });
                      
                      const e = p.then(() => {
                          1. Keep e as closure variable for later, for when the promise does get resolved in Promise.race line
                          2. find that e in executing array
                          3. Remove it
                      });
                      
                      async function promiseMapLimit(
                        array,
                        poolLimit,
                        iteratorFn,
                      ) {
                        const ret = [];
                        const executing = [];
                        for (const item of array) {
                          const p = Promise.resolve().then(() => iteratorFn(item, array));
                          ret.push(p);
                        }
                        if (poolLimit > array.length) {
                          // if poolLimit and greater that array just resolve all the promises and no need to worry of concurrency
                          return Promise.all(ret);       
                        }
                        for (const p of ret) {
                            // Add self remove logic to each promise element
                            const e = p.then(() => executing.splice(executing.indexOf(e), 1));
                            // Put the promise element in execution queue
                            executing.push(e);
                            // Whenever the execution ques is full wait for execution of the promises
                            // Promise.race awaits for all the promises to finish execution
                            // And because of the self removal logic execution queue also becomes empty
                            if (executing.length >= poolLimit) {
                              await Promise.race(executing);
                            }
                        }
                        // Promise.all will take care of all the promises remaining in the last batch for which await Promise.race(executing); was not executed.
                        return Promise.all(ret);
                      }
                      
                      async function promiseMapLimit(
                        array,
                        poolLimit,
                        iteratorFn,
                      ) {
                        const ret = [];
                        const executing = [];
                        for (const item of array) {
                          const p = Promise.resolve().then(() => iteratorFn(item, array));
                          ret.push(p);
                      
                          if (poolLimit <= array.length) {
                            const e = p.then(() => executing.splice(executing.indexOf(e), 1));
                            executing.push(e);
                            if (executing.length >= poolLimit) {
                              await Promise.race(executing);
                            }
                          }
                        }
                      
                        return Promise.all(ret);
                      }
                      
                      promiseMapLimit([1, 2, 3], 1, async function (i) => { return 2 * i });
                      
                      const e = p.then(() => {
                          1. Keep e as closure variable for later, for when the promise does get resolved in Promise.race line
                          2. find that e in executing array
                          3. Remove it
                      });
                      
                      async function promiseMapLimit(
                        array,
                        poolLimit,
                        iteratorFn,
                      ) {
                        const ret = [];
                        const executing = [];
                        for (const item of array) {
                          const p = Promise.resolve().then(() => iteratorFn(item, array));
                          ret.push(p);
                        }
                        if (poolLimit > array.length) {
                          // if poolLimit and greater that array just resolve all the promises and no need to worry of concurrency
                          return Promise.all(ret);       
                        }
                        for (const p of ret) {
                            // Add self remove logic to each promise element
                            const e = p.then(() => executing.splice(executing.indexOf(e), 1));
                            // Put the promise element in execution queue
                            executing.push(e);
                            // Whenever the execution ques is full wait for execution of the promises
                            // Promise.race awaits for all the promises to finish execution
                            // And because of the self removal logic execution queue also becomes empty
                            if (executing.length >= poolLimit) {
                              await Promise.race(executing);
                            }
                        }
                        // Promise.all will take care of all the promises remaining in the last batch for which await Promise.race(executing); was not executed.
                        return Promise.all(ret);
                      }
                      

                      Community Discussions

                      Trending Discussions on Concurrency
                      • Swift Concurrency announced for iOS 13 in Xcode 13.2 - how did they achieve this?
                      • iOS: Concurrency is only available in iOS 15.0.0 or newer in protocol
                      • A failure occurred while executing org.jetbrains.kotlin.gradle.internal.KaptWithoutKotlincTask$KaptExecutionWorkAction?java.lang.reflect.Invocation?
                      • PRECONDITION_FAILED: Delivery Acknowledge Timeout on Celery &amp; RabbitMQ with Gevent and concurrency
                      • Can another thread see an effectively immutable object in an inconsistent state if it is published with a volatile reference?
                      • Limit GitHub action workflow concurrency on push and pull_request?
                      • How to limit concurrent http requests with Mono &amp; Flux
                      • AWS Checking StateMachines/StepFunctions concurrent runs
                      • Generic requirement that Some: AsyncSequence is not throwing
                      • How to prevent actor reentrancy resulting in duplicative requests?
                      Trending Discussions on Concurrency

                      QUESTION

                      Swift Concurrency announced for iOS 13 in Xcode 13.2 - how did they achieve this?

                      Asked 2022-Mar-11 at 12:26

                      Xcode 13.2 Beta release notes features a promise for Swift Concurrency support for iOS 13.

                      You can now use Swift Concurrency in applications that deploy to macOS 10.15, iOS 13, tvOS 13, and watchOS 6 or newer. This support includes async/await, actors, global actors, structured concurrency, and the task APIs. (70738378)

                      However, back in Summer 2021 when it first appeared at WWDC it was hard constrained to be run on iOS 15+ only.

                      My question is: what changed? How did they achieve backwards compatibility? Does it run in any way that is drastically different from the way it would run in iOS 15?

                      ANSWER

                      Answered 2021-Oct-28 at 14:06

                      Back-deploying concurrency to older OS versions bundles a concurrency runtime library along with your app with the support required for this feature, much like Swift used to do with the standard library prior to ABI stability in Swift 5, when Swift could be shipped with the OS.

                      This bundles parts of the Concurrency portions of the standard library (stable link) along with some additional support and stubs for functionality (stable link).

                      This bundling isn't necessary when deploying to OS versions new enough to contain these runtime features as part of the OS.


                      Since the feature on iOS 15+ (and associated OS releases) was stated to require kernel changes (for the new cooperative threading model) which themselves cannot be backported, the implementation of certain features includes shims based on existing functionality which does exist on those OSes, but which might perform a little bit differently, or less efficiently.

                      You can see this in a few places in Doug Gregor's PR for backporting concurrency — in a few places, checks for SWIFT_CONCURRENCY_BACK_DEPLOYMENT change the implementation where some assumptions no longer hold, or functionality isn't present. For example, the GlobalExecutor can't make assumptions about dispatch_get_global_queue being cooperative (because that threading model doesn't exist on older OSes), so when backporting, it has to create its own queue for use as the global cooperative queue. @objc-based actors also need to have their superclass swizzled, which doesn't need to happen on non-backdeployed runtimes. (Symbols also have to be injected in some places into the backdeploy libs, and certain behaviors have to be stubbed out, but that's a bit less interesting.)

                      Overall, there isn't comprehensive documentation on the exact differences between backdeploying and not (short of reading all of the code), but it should be safe to assume that the effective behavior of the backdeployed lib will be the same, though potentially at the cost of performance.

                      Source https://stackoverflow.com/questions/69746388

                      Community Discussions, Code Snippets contain sources that include Stack Exchange Network

                      Vulnerabilities

                      No vulnerabilities reported

                      Install Concurrency

                      You can download it from GitHub.
                      You can use Concurrency like any standard Java library. Please include the the jar files in your classpath. You can also use any IDE and you can run and debug the Concurrency component as you would do with any other Java program. Best practice is to use a build tool that supports dependency management such as Maven or Gradle. For Maven installation, please refer maven.apache.org. For Gradle installation, please refer gradle.org .

                      Support

                      For any new features, suggestions and bugs create an issue on GitHub. If you have any questions check and ask questions on community page Stack Overflow .

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