libuv | Cross-platform asynchronous I/O | Socket library

 by   libuv C Version: v1.45.0 License: MIT

kandi X-RAY | libuv Summary

kandi X-RAY | libuv Summary

libuv is a C library typically used in Networking, Socket applications. libuv has no bugs, it has no vulnerabilities, it has a Permissive License and it has medium support. You can download it from GitHub.

libuv is a multi-platform support library with a focus on asynchronous I/O. It was primarily developed for use by Node.js, but it's also used by Luvit, Julia, uvloop, and others.

            kandi-support Support

              libuv has a medium active ecosystem.
              It has 21631 star(s) with 3378 fork(s). There are 706 watchers for this library.
              There were 1 major release(s) in the last 12 months.
              There are 106 open issues and 1470 have been closed. On average issues are closed in 285 days. There are 50 open pull requests and 0 closed requests.
              It has a neutral sentiment in the developer community.
              The latest version of libuv is v1.45.0

            kandi-Quality Quality

              libuv has 0 bugs and 0 code smells.

            kandi-Security Security

              libuv has no vulnerabilities reported, and its dependent libraries have no vulnerabilities reported.
              libuv code analysis shows 0 unresolved vulnerabilities.
              There are 0 security hotspots that need review.

            kandi-License License

              libuv is licensed under the MIT License. This license is Permissive.
              Permissive licenses have the least restrictions, and you can use them in most projects.

            kandi-Reuse Reuse

              libuv releases are available to install and integrate.
              Installation instructions, examples and code snippets are available.
              It has 189 lines of code, 9 functions and 4 files.
              It has low code complexity. Code complexity directly impacts maintainability of the code.

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            libuv Key Features

            No Key Features are available at this moment for libuv.

            libuv Examples and Code Snippets

            No Code Snippets are available at this moment for libuv.

            Community Discussions


            Map or table of libuv converstions to ANSI?
            Asked 2022-Mar-29 at 09:42

            I am trying to fix an implementation of readline for the browser, and it would be nice if I could have the same behaviour that libuv for windows does. I want to know where can I find which keycodes maps to what? For example from we know that



            Answered 2022-Mar-29 at 09:42

            I didn't find this table documented anywhere, but I am going to post the data that I got by experimentally trying all the keys in my keyboard available, hope this helps someone. I prefix the keys with 'c' to mean that control was pressed, and 's' to mean that shift was pressed.



            nodejs-16 dependency issue with libuv
            Asked 2022-Mar-23 at 17:38

            This is what I'm getting on my Amazon Linux 2 instance while trying to run yum update.

            Do you suggest I use --skip-broken or wait until AWS rolls out a fix?



            Answered 2022-Feb-09 at 19:06

            Yeah, plus 1 to this issue. OP, the --skip-broken flag will only temporarily fix your currently running servers though. If you're baking any new AMIs or spinning up any new EC2s with Terraform, CDK, etc, that --skip-broken flag won't work as its not available as part of the aws cloud.init script. This will cause any new AMI or EC2 creations to timeout and fail.

            One potential work around is to try compiling libuv directly from source as > 1.39 sadly isn't currently available from any linux distro.



            detach().cpu() kills kernel
            Asked 2022-Feb-28 at 22:25

            I am trying to plot an image noise using pytorch, however, when I reach to that point, the kernel dies. I am attempting the same code at Google Colab where I do get results

            Result at Google Colab

            Result at Jupyter

            I do not think that it has something to do with the code itself, but I am posting the function to plot the grid:



            Answered 2022-Feb-28 at 22:25

            After a few days I was able to find the solution

            Firstly, my code needed to be fixed to correctly call the params needed with the proper name



            How does the Nodejs do i/o under the hood?
            Asked 2022-Jan-16 at 16:14

            I know that nodejs uses the thread pool provided by the libuv to do concurrent jobs. I read that nodejs just needs one of those threads to do all the i/o bound activities

            Then how do the non-blocking file operations happen?

            What will actually happen under the hood in between node, disk, and os, if I iterate over a folder containing 100 files open all of them using readFile()?

            If doing this same operation in some other multithreaded and blocking language will result in threads waiting for the i/o to finish, then who waits for i/o to finish in nodejs? , especially when there are multiple file operations happening simultaneously ?

            Thank you !



            Answered 2022-Jan-16 at 16:14

            File IO in nodejs uses a thread pool. By default, there are 4 threads in the pool.

            When some Javascript calls a file operation such as in nodejs, the call is routed to some native code within the libuv library in the nodejs implementation. That code adds the specific file operation to a queue of items waiting for an OS thread. If an OS thread is immediately available, then that OS thread is given the task of carrying out the file operation and then the original libuv function returns which returns back to the original Javascript and nodejs continues running other Javascript.

            Then, sometime later the thread finishes the file operation and has a result. It inserts an event into the nodejs event queue with the completed result and the original callback passed with the original file operation.

            When nodejs has finished executing any other Javascript it was running, it pulls the next event from the event queue and calls the Javascript callback associated with that event and passes it the data associated with the event. This triggers the Javascript callback that was originally passed to to get called.

            If, in the second step above, there were no available threads in the thread pool, then the task is added to a queue and libuv immediately returns control back to nodejs so it can run other Javascript. Sometime later when one of the existing threads in the pool completes and finishes its work of adding an event to the event queue, then it will pull the next item out of the the thread pool queue, give it the now-available thread and let it start running its operation.

            In this way, all file operations appear to be non-blocking and asynchronous from the Javascript side of things. They either get started immediately if there is an available thread in the thread pool or they sit in a thread pool queue until a thread is available. That part is invisible to the Javascript side of things. Either way, the operation is initiated or queued and control immediately returns back to nodejs to continue running other Javascript. And, either way, the operation completes sometime later and the Javascript callback associated with the file operation gets called via the Javascript event queue. This provides the asynchronous, non-blocking, event-driven mechanism that nodejs uses for all file I/O.



            Python C API Undefined symbols for architecture x86_64
            Asked 2022-Jan-01 at 16:23

            I'm trying to compile a file that makes use of Python's C API. I'm working in a conda enviroment, running on macOS Monterey. I'm compiling using GCC as following:



            Answered 2022-Jan-01 at 06:20

            This command: gcc file.o -o a.out does not link to a python library.

            You need to add (append) -lpython3 and possibly -L${CONDA_PREFIX}/lib/python3.9 to it.



            libcurl - multi_socket - how it Working + directly IOCP?
            Asked 2021-Dec-29 at 09:57

            I have an implemented interface based IO Completion Ports Windows - I want to try and use it together with libcurl.

            The online book curl says that:

            There are numerous event based systems to select from out there, and libcurl is completely agnostic to which one you use. libevent, libev and libuv are three popular ones but you can also go directly to your operating system's native solutions such as epoll, kqueue, /dev/poll, pollset, Event Completion or I/O Completion Ports.

            I am reading online Curl book chapter on multi socket: "multi_socket" interface

            It says:

            libcurl informs the application about socket activity to wait for with a callback called CURLMOPT_SOCKETFUNCTION. Your application needs to implement such a function:

            Using this, libcurl will set and remove sockets your application should monitor. Your application tells the underlying event-based system to wait for the sockets. This callback will be called multiple times if there are multiple sockets to wait for, and it will be called again when the status changes and perhaps you should switch from waiting for a writable socket to instead wait for it to become readable.

            The devil himself can't figure out how it works.

            -For example:

            -Created completion port: CreateIoCompletionPort ()

            -Created completion port handler: GetQueuedCompletionStatus ()

            -Created a windows asynchronous socket: WSASocket ()

            -filled in all the necessary structures like - sockadrr

            -Connected to remote server: WSAConnect ()

            -Linked socket to the IO Completion Port.

            -Called the WSASend () and send to server message.

            -Now I want libcurl to read the message from the server and do all the necessary actions, but I absolutely cannot understand from the description how ???

            libcurl informs the application about socket activity to wait for with a callback called CURLMOPT_SOCKETFUNCTION.

            How is this call -back function called? Who will call her? Where ? why and why ?? I do not understand (((((

            Please, help :(



            Answered 2021-Dec-29 at 09:57

            Unfortunately it turned out - that Libcurl multi_socket mode cannot work with Windows IOCP.



            libuv vs asyncio (python)
            Asked 2021-Dec-20 at 13:26

            I have been trying to find the difference in implementation of the uvloop and inbuilt asyncio that comes up with python. Apart from the fact that libuv the base of uvloop is written in c++, there is no other factor that is mentioned in the web. I would like to know about the other factors that affect the asyncio [erfomance between them.

            Also on a side-note this blog consists of performance difference stream and normal async io, isn't stream generated from the asyncio and thus dependent on each other?



            Answered 2021-Dec-20 at 13:26

            As you said, uvloop is written in Cython (equivalent to c) on top of libuv.

            Writing code in Cython is almost guaranteed to give you a noticeable speed boost which is exactly what's happening here. No need for any other difference. It's much like numpy doing operations faster than writing normally in Python.

            For your other question: The difference between asyncio and asyncio-streams is that streams are built on top of the basic asyncio.

            Asyncio uses transports and protocols, the first responsible for writing to the socket, and the second for handling data received by the socket.

            Streams are simple constructs built on top of both, and have an easier to use interface that mimics regular files or sockets.



            Homebrew node installation fails on cannot link c-ares
            Asked 2021-Dec-08 at 22:48

            If I run brew install node I get this error:

            ==> Installing dependencies for node: c-ares, icu4c, libnghttp2, libuv and openssl@1.1 Error: Cannot link c-ares Another version is already linked: /usr/local/Cellar/c-ares/1.17.1

            Anybody know how to resolve this?



            Answered 2021-Dec-08 at 22:48

            Hm, it appears Homebrew tried to upgrade c-ares from version 1.17.1 to 1.18.1 but failed for some reason. Try running brew upgrade c-ares before brew install node.

            If that doesn't work, what is your output for brew list --versions c-ares? Perhaps you have multiple c-ares versions installed. If that is the case, run brew unlink c-ares to unlink the old version and then brew link c-ares to link the newer one. The old version can be uninstalled by running brew cleanup c-ares



            Where is Node.js own dependencies (V8, libuv) located locally?
            Asked 2021-Dec-05 at 07:30

            I looked at Node.js's documentation:

            "Node.js includes a number of other statically linked libraries including OpenSSL. These other libraries are located in the deps/ directory in the Node.js source tree."

            I installed Node.js and check out the directory Program files/nodejs, but I cannot find the deps/directory? Where is V8, libuv being stored in my local files?



            Answered 2021-Dec-05 at 07:30

            Node is a program where its C/C++, static libraries it uses (such as libuv) and various other resources it uses are compiled into node.exe (on Windows). So, the things you're asking about are inside of node.exe.

            They are not separately available in your file system when you just install the runnable version of nodejs.

            If you cloned the source repository and built it yourself, you'd have all the components in your local source repository that are then compiled into node.exe. But, if you install an already built version of nodejs, then you will just get the binary executable files that already have the components built into them.



            UnsatisfiableError on importing environment pywin32==300 (Requested package -> Available versions)
            Asked 2021-Dec-03 at 14:58

            Good day

            I am getting an error while importing my environment:



            Answered 2021-Dec-03 at 09:22

            Build tags in you environment.yml are quite strict requirements to satisfy and most often not needed. In your case, changing the yml file to


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


            No vulnerabilities reported

            Install libuv

            For UNIX-like platforms, including macOS, there are two build methods: autotools or CMake.
            One of: Visual C++ Build Tools Visual Studio 2015 Update 3, all editions including the Community edition (remember to select "Common Tools for Visual C++ 2015" feature during installation). Visual Studio 2017, any edition (including the Build Tools SKU). Required Components: "MSbuild", "VC++ 2017 v141 toolset" and one of the Windows SDKs (10 or 8.1).
            Basic Unix tools required for some tests, Git for Windows includes Git Bash and tools which can be included in the global PATH.
            Note to OS X users:. Make sure that you specify the architecture you wish to build for in the "ARCHS" flag. You can specify more than one by delimiting with a space (e.g. "x86_64 i386").


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