Async use cases

[EdmondDantes]

In this thread you may share examples of tasks you have already solved using async in PHP, or tasks that would be easier to solve with it.
You may include code examples if you wish.
This topic may become useful for shaping the API.

You will also help other PHP developers learn something new or look at old problems from a different perspective.
That’s why this thread can be extremely useful for everyone!

[danog]

IMO this is a given (otherwise we wouldn't even be having this discussion), but since it wasn't spelled out, concurrency allows for:

• Higher performance with entirely local caching
• HIgher performance by concurrent execution of I/O (read, write files at the same time, increasing throughput; fetch multiple URLs at the same time, over a single http/2 connection, increasing throughput and removing overhead (curl_multi_init was added for this reason))
• Much easier background execution of tasks
• Higher request throughput, due to the greatly reduced setup overhead per-request (non-async worker-mode can also help, but concurrency has the added performance benefit of reducing context switches)

Other languages have introduced concurrency for these reasons and many more, PHP is the only one left behind, and that's all there is to it.