Asynchronous concurrent multithreading support

[jasonccs]

Description

Asynchronous concurrent multithreading support. With the development of the network, it is necessary for the official to install such a module by default, which is convenient for developers to continue using PHP,

[iluuu1994]

Hi @jasonccs!

PHP provides the low-level mechanisms for concurrent programming. It has both coroutines, as well as fibers, and allows for non-blocking IO. These can be used (and have been used) to build concurrent APIs. For example, have a look at amphp. Backing it into the language is questionable, because to make proper use of concurrency, the language would also need to provide a way to process requests concurrently (so that another request can execute while the other is blocked). However, this also means moving away from isolated requests, which is a huge paradigm shift.

As for parallel programming, you can use parallel. The reasoning why PHP doesn't provide these is similar: Parallel programming is generally not super useful in a web-programming context. Threads are expensive, and short-lived requests spinning up threads is generally not practical.

[Gemorroj]

@iluuu1994 the main problem for asyns programming in php is - the need for data serialization. we cannot use one db connection or curl connetion or other non serializable data for threads (see https://github.com/amphp/serialization/tree/1.x/src).

[iluuu1994]

@Gemorroj Can't you create a separate connection for each thread? I've never worked with parallel, but as far as I understand, parallel works by communicating between threads through channels, rather than sharing memory itself (popularized by Go). The DB extension would likely need to wrap the connection in a mutex anyway, if the protocol doesn't support multiplexing.

[Gemorroj]

@iluuu1994
I have not worked with parallel. Because its prospects are vague, see krakjoe/parallel#201 (comment) .
Although, at first glance, this is exactly what I need.
And yes, for a large project it is difficult to isolate code that can be serialized. In my case, it is a Symfony container. Here is a minimal example. https://github.com/Gemorroj/parallel-nonserializable

[danog]

@Gemorroj You're confusing threads with fibers.

Fibers do not need serialization to work, and amphp libraries never use serialization to interact between fibers.

https://github.com/amphp/mysql, https://github.com/amphp/http-client, https://github.com/amphp/postgres, etc NEVER use serialization when interacting between concurrent fibers.

All amphp libraries do NOT use threads, because threads are not needed to do async operations with fibers.

https://github.com/amphp/parallel is the only library that uses threads through karkjoe/parallel, pthreads or other solutions automatically, and it should be used only to do CPU-bound operations (mainly just cryptography and super heavy maths); basically, in the vast majority applications you will never use it.