Asynchronous | Implementation-agnostic asynchronous code | Reactive Programming library

That happens, because you're trying to update state asynchronously, and the update could happen when the component is unmounted.

You can keep a ref that will check if the component is mounted or not like in the code below.

Because I can't see the implementation of the AxiosGetData, you can just check is that ref is true, when you will consume the promise from the axios.

When running the gunicorn command, you can try to add workers parameter with using options -w or --workers.

It defaults to 1 as stated in the gunicorn documentation. You may want to try to increase that value.

Example usage:

There are 2 different Event Loops:

1. Browser Event Loop
2. NodeJS Event Loop

The Event Loop is a process that runs continually, executing any task queued. It has multiple task sources which guarantees execution order within that source, but the Browser gets to pick which source to take a task from on each turn of the loop. This allows Browser to give preference to performance sensitive tasks such as user-input.

There are a few different steps that Browser Event Loop checks continuously:

• Task Queue - There can be multiple task queues. Browser can execute queues in any order they like. Tasks in the same queue must be executed in the order they arrived, first in - first out. Tasks execute in order, and the Browser may render between tasks. Task from the same source must go in the same queue. The important thing is that task is going to run from start to finish. After each task, Event Loop will go to Microtask Queue and do all tasks from there.

• Microtasks Queue - The microtask queue is processed at the end of each task. Any additional microtasks queued during during microtasks are added to the end of the queue and are also processed.

• Animation Callback Queue - The animation callback queue is processed before pixels repaint. All animation tasks from the queue will be processed, but any additional animation tasks queued during animation tasks will be scheduled for the next frame.

• Rendering Pipeline - In this step, rendering will happen. The Browser gets to decide when to do this and it tried to be as efficient as possible. The rendering steps only happen if there is something actually worth updating. The majority of screens update at a set frequency, in most cases 60 times a second (60Hz). So, if we would change page style 1000 times a second, rendering steps would not get processed 1000 times a second, but instead it would synchronize itself with the display and only render up to a frequency display is capable of.

Important thing to mention are Web APIs, that are effectively threads. So, for example setTimeout() is an API provided to us by Browser. When you call setTimeout() Web API would take over and process it, and it will return the result to the main thread as a new task in a task queue.

The best video I found that describes how Event Loops works is this one. It helped me a lot when I was investigating how Event Loop works. Another great videos are this one and this one. You should definitely check all of them.

NodeJS Event Loop allows NodeJS to perform non-blocking operations by offloading operation to the system kernel whenever possible. Most modern kernels are multi-threaded and they can perform multiple operations in the background. When one of these operations completes, the kernel tells NodeJS.

Library that provides the Event Loop to NodeJS is called Libuv. It will by default create something called Thread Pool with 4 threads to offload asynchronous work to. If you want, you can also change the number of threads in the Thread Pool.

NodeJS Event Loop goes through different phases:

• timers - this phase executes callbacks scheduled by setTimeout() and setInterval().

• pending callbacks - executes I/O callbacks deferred to the next loop iteration.

• idle, prepare - only used internally.

• poll - retrieve new I/O events; execute I/O related callbacks (almost all with the exception of close callbacks, the ones scheduled by timers, and setImmediate()) Node will block here when appropriate.

• check - setImmediate() callbacks are invoked here.

• close callbacks - some close callbacks, e.g. socket.on('close', ...).

Between each run of the event loop, Node.js checks if it is waiting for any asynchronous I/O or timers and shuts down cleanly if there are not any.

In Browser, we had Web APIs. In NodeJS, we have C++ APIs with the same rule.

I found this video to be useful if you want to check for more information.

You need to create a secondary thread where you run your async code. You initialize the secondary thread with its own event loop, which runs forever. Execute each async function by calling run_coroutine_threadsafe(), and calling result() on the returned object. That's an instance of concurrent.futures.Future, and its result() method doesn't return until the coroutine's result is ready from the secondary thread.

Your main thread is then, in effect, calling each async function as if it were a sync function. The main thread doesn't proceed until each function call is finished. BTW it doesn't matter if your sync function is actually running in an event loop context or not.

The calls to result() will, of course, block the main thread's event loop. That can't be avoided if you want to get the effect of running an async function from sync code.

Needless to say, this is an ugly thing to do and it's suggestive of the wrong program structure. But you're trying to convert a legacy program, and it may help with that.

• StreamReader.ReadLine() is blocking by design.

• There is an asynchronous alternative, .ReadLineAsync(), which returns a Task instance that you can poll for completion, via its .IsCompleted property, without blocking your foreground thread (polling is your only option in PowerShell, given that it has no language feature analogous to C#'s await).

Here's a simplified example that focuses on asynchronous reading from a StreamReader instance that happens to be a file, to which new lines are added only periodically; use Ctrl-C to abort.

I would expect the code to work the same if you adapt it to your stdout-reading System.Diagnostics.Process code.

Given you mentioned Supply.merge, let's start with that. Imagine it wasn't in the Raku standard library, and we had to implement it. What would we have to take care of in order to reach a correct implementation? At least:

1. Produce a Supply result that, when tapped, will...
2. Tap (that is, subscribe to) all of the input supplies.
3. When one of the input supplies emits a value, emit it to our tapper...
4. ...but make sure we follow the serial supply rule, which is that we only emit one message at a time; it's possible that two of our input supplies will emit values at the same time from different threads, so this isn't an automatic property.
5. When all of our supplies have sent their done event, send the done event also.
6. If any of the input supplies we tapped sends a quit event, relay it, and also close the taps of all of the other input supplies.
7. Make very sure we don't have any odd races that will lead to breaking the supply grammar emit* [done|quit].
8. When a tap on the resulting Supply we produce is closed, be sure to close the tap on all (still active) input supplies we tapped.

Good luck!

So how does the standard library do it? Like this:

Found it! If you use ILSpy to disassemble the .dll compiled from the question's code (use the .NET Fiddle link and follow the question's instructions), and then turn ILSpy's language version down to C# 4 (which was the version before async/await was introduced), then you'll see that this is how the GetValueAsync method is implemented:

I'm the author of the article you referenced.

As discussed in Discover concurrency in SwiftUI, views can make use of the new .task { } and .refreshable { } modifiers to fetch data asynchronously.

So you now have the following options to call you async code: