circuit-b | A non intrusive circuit breaker for node.js | Runtime Evironment library
kandi X-RAY | circuit-b Summary
kandi X-RAY | circuit-b Summary
A circuit breaker provides latency and fault protection for distributed systems. A circuit breaker monitor outgoing requests, and will trip an internal circuit if it begins to detect that the remote service is failing. By doing so, one can redirect requests to sane fallbacks, and back-off requests against downstream services so they can recover. This pattern is described in detail in the akka documentation. Circuit-b is non intrusive in the way that one do not need to implement it every single place one do a http call in an application. One only need to init Circuit-b one place in an application and it will intercept all http calls. When that is said; one can init Circuit-b multiple times if wanted. Under the hood Circuit-b use async hooks to intercept http calls on the net socket level so there is no altering of the global http object in node or any global singletons. By using this approach there is a clear separation between the code doing http calls and the code doing circuit breaking.
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circuit-b Key Features
circuit-b Examples and Code Snippets
Lines of Code : 16License : Permissive (MIT License)
Copydef level(self) -> int:
"""
:return: Number of forward references
>>> node = Node("Key", 2)
>>> node.level
0
>>> node.forward.append(Node("Key2", 4))
>>> def __init__(self, c_op, g):
self._c_op = c_op
self._graph = g
self._outputs = None # Initialized by _duplicate_body_captures_in_cond().
self._id_value = g._add_op(self, self.name)
self._is_stateful = False @Around("@annotation(com.baeldung.hystrix.HystrixCircuitBreaker)")
public Object circuitBreakerAround(final ProceedingJoinPoint aJoinPoint) {
return new RemoteServiceCommand(config, aJoinPoint).execute();
} Community Discussions
Trending Discussions on circuit-b
QUESTION
There is a ActiveMQ queue (QueueA). A service (MyService) subscribes to messages, processes it and sends the message to another ActiveMQ queue (QueueB).
ANSWER
Answered 2021-Jun-01 at 09:43Have a look on the Camel RoutePolicy of type ThrottlingExceptionRoutePolicy which is based on the CircuitBreakerLoadBalancer.
Using this policy should allow you to stop consuming from the endpoint when the circuit is in the open state (to compare with the standard circuit behahiour : bypass the service call, and fallback to another response).
QUESTION
I am currently using Vertx CircuitBreaker to attempt retry on requesting event bus. Based on the ReplyException.ReplyFailure I want to skip or avoid retries.
For example I don't want retry when the event bus responds with ReplyFailure.RECIPIENT_FAILURE, because this kind of error are not application error instead logic validation failure.
Below is my code,
...ANSWER
Answered 2021-May-21 at 15:55This is not currently supported by the Vert.x Circuit Breaker API. There is an open issue about it here. There's also a PR that attempts to fix it, but it has been sitting around for a year now. Not sure why it never got reviewed.
QUESTION
In order to achieve High Availability we have created two blob containers under different storage accounts at different Azure regions.
So that, if application find issues while WRITING to primary blob container, application will perform circuit-breaker logic and if issue persists even after threshold number of attempts, application will start WRITING to stand-by blob storage account which is located in different Azure location & this architecture works fine.
Code used to switch from primary to secondary:
...ANSWER
Answered 2021-Mar-12 at 07:20First, as you may know, there is no official docker image of Azcopy available. The github issue mentions it.
And yes, you can use azure function to do it(about ADF, not sure, but asked some guys, they say it's not easy to do that), but it may a little difficult.
The easier solution is to use azure web job and azcopy together. Just specify the webjob as schedule when creating it in azure portal. Azure webjob supports many file types like .ps1(powershell), .cmd, .py etc. So it's very easy to use one of your favorites to create it.
Here, I will create a .ps1(powershell) file, then upload it to azure webjob to execute the sync job on scheduled time.
Step 1: create a .ps1 file. The name of the file must be run.ps1. Then use the code below in the run.ps1 file(please use your own source storage and destination storage in the code):
QUESTION
I'm trying to figure out what is the best wait to implement a circuit breaker based of the number of requests been served in a Typescript/express application instead of fails percentage.
Since the application is meant to be executed by large number of users and under a heavy load, I'm trying to customize the response code in order to trigger a horizontal scaling event with k8s/istio.
The first thing I want to start with is to get is the number of requests in nodejs eventloop event if there is some async work in progress, because a big part of my request are executed asynchronously using async/await.
BTW:
I have seen these Libs
Is there any good Idea/path I can start with in order to make this possible ?
...ANSWER
Answered 2021-Jan-04 at 00:24I can't tell for sure from your question, but if what you're trying to do is to just keep track of how many requests are in progress and then do something in particular if that number exceeds a particular value, then you can use this middleware:
QUESTION
I want to use Polly to implement a Circuit Breaker pattern.
In the docs, there is a description of the Half Open state, and there it says:
- If a handled exception is received, that exception is rethrown, and the circuit transitions immediately back to open, and remains open again for the configured timespan.
- If an unhandled exception is received, the circuit remains in half-open.
I'm not sure I understand the difference here between handled and unhandled exception. We are describing a case where an action is run by the policy and is throwing an exception.
When they say the exception is handled, where do they mean it's being handled? because as we said, the action threw it so doesn't it mean it's unhandled?
It makes me not understand completely when the half open state remains half open and when does it transition to open.
...ANSWER
Answered 2020-Nov-25 at 12:46When you define a Circuit Breaker policy then you can define what sort of exception(s) should be considered by the CB implementation. In other words you can list those exceptions that should be treated as failed execution and should be counted into the successive failure count.
You can define the list of exceptions with the combination of Handle and Or method calls.
Let's scrutinize this concept via a simple example:
QUESTION
I get above error when I'm trying to create a persisting actor with SQL server persistence.
EDIT: what's weird when I clone repositories akka and akka persistence sql server and attach then instead using nuget packages is working as expected. I'm using followinf versions: "Akka" Version="1.4.11" "Akka.Persistence.SqlServer" Version="1.4.10"
...ANSWER
Answered 2020-Nov-11 at 23:49You ran into this issue, which was the result of us changing some APIs inside the CircuitBreaker as part of Akka.NET v1.4.11: https://github.com/akkadotnet/Akka.Persistence.SqlServer/issues/177
We just pushed Akka.Persistence.SqlServer 1.4.11 a couple of minutes ago: https://github.com/akkadotnet/Akka.Persistence.SqlServer/releases/tag/1.4.11 - upgrading to this version should resolve your issue.
QUESTION
I got alert stating elasticsearch has 2 unassigned shards. I made below api calls to gather more details.
...ANSWER
Answered 2020-Oct-31 at 01:00two things here, shard allocation exception and circuit breaker exception(nested exception as it looks).
Please use the below command in your cluster to re-trigger the allocation as previous all retry was failed and the same is suggested in your exception message if you carefully notice. more info on below command is on this related Github issue comment.
curl -XPOST ':9200/_cluster/reroute?retry_failed
If still, it doesn't work, then you have to fix the parent circuit breaker exception, you should use the http://localhost:9200/_nodes/stats API to know the exact heap of your ES nodes, and accordingly increase it.
QUESTION
My understanding of the Bulkhead pattern is that it's a way of isolating thread pools. Hence, interactions with different services use different thread pools: if the same thread pool is shared, one service timing out constantly might exhaust the entire thread pool, taking down the communication with the other (healthy) services. By using different ones, the impact is reduced.
Given my understanding, I don't see any reason to apply this pattern to non-blocking applications as threads don't get blocked and, therefore, thread pools wouldn't get exhausted either way.
I would appreciate if someone could clarify this point in case I'm missing something.
EDIT (explain why it's not a duplicate):
There's another (more generic) question asking about why using Circuit-Breaker and Bulkhead patterns with Reactor. The question was answered in a very generic way, explaining why all Resilience4J decorators are relevant when working with Reactor.
My question, on the other hand, is particular to the Bulkhead pattern, as I don't understand its benefits on scenarios where threads don't get blocked.
...ANSWER
Answered 2020-Oct-23 at 07:58The Bulkhead pattern is not only about isolating thread pools.
Think of Little's law: L = λ * W
Where:
L – the average number of concurrent tasks in a queuing system
λ – the average number of tasks arriving at a queuing system per unit of time
W – the average service time a tasks spends in a queuing system
The Bulkhead pattern is more about controlling L in order to prevent resource exhaustion. This can be done by using:
- bounded queues + thread pools
- semaphores
Even non-blocking applications require resources per concurrent task which you might want to restrict. Semaphores could help to restrict the number of concurrent tasks.
The RateLimiter pattern is about controlling λ and the TimeLimiter about controlling the maximum time a tasks is allowed to spend.
An adaptive Bulkhead can even replace RateLimiters. Have a look at this awesome talk "Stop Rate Limiting! Capacity Management Done Right" by Jon Moore"
We are currently developing an AdaptiveBulkhead in Resilience4j which adapts the concurrency limit of tasks dynamically. The implementation is comparable to TCP Congestion Control algorithms which are using an additive increase/multiplicative decrease (AIMD) scheme to dynamically adapt a congestion window. But the AdaptiveBulkhead is of course protocol-agnostic.
QUESTION
I am using npm pg ("pg": "^7.18.2", "pg-native": "^3.0.0" in my package.json), at which I am new, to connect my newbie node app to a postgresql database. I use docker-compose to start up everything using this configuration:
ANSWER
Answered 2020-Oct-02 at 17:20Finally having some time to go further this issue. I uninstall the two pg modules in my fibserver application and install pg again provides me a new version of npm pg module (8.3.3) without having the native part which I probably installed by mistake. Single javascript pg library does the job.
QUESTION
Based on what I've seen on other stackoverflow pages:
- Does all(list) use short circuit evaluation?
- Do all() and any() always short-circuit in order?
- Is the shortcircuit behaviour of Python's any/all explicit?
the following code should short circuit:
...ANSWER
Answered 2020-Jul-20 at 03:10Yes, short circuting happens in python
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