8/14/2023 0 Comments Php sleep vs wait![]() There's no context switching between coroutines on the OS level. But let's call it "coroutines" because it's the most used term.Ī coroutine is like a thread in that it shares the memory of the process it was created inside, but it's not an actual thread because the OS knows nothing about it. Execute in coroutines/fibers/green-threads In addition to all this, multithreading in PHP is not supported anymore. Because the CPU cores are switching between a lot of contexts.Īlso, with the same memory space being accessed by multiple threads at the same time, race conditions may happen. When you have too many threads, as the case with too many processes, everything on your machine will slow down. However, context switching still happens. That makes spawning threads less expensive than spawning processes. All threads live in the same memory space as the process. Ok? Execute in different threadsĪ process has its own private space in memory, a process may have multiple threads. Don't just read this and think that multiprocessing and queues are bad. So when I say that it's not the most performant I'm speaking relative to the other options. Multiprocessing and Laravel workers have been doing great for millions of apps. Also with workers, you need to manage how you can receive the results from your code execution inside the workers. ![]() However, the overhead of context switching and memory allocation will still apply. That way you won't have to create new processes each time you want to run something async. You could use Laravel queues and start a fixed number of workers (processes) and keep them alive to process your tasks. Switching between processes (context switching) also has an overhead. Because creating processes is relatively expensive and each process requires its own private space in memory. Multiprocessing is an easy way to achieve asynchronous code execution in PHP. Then waits until any of the requests return before it continues the process. So while the CPU waits for a response on the first request, it sends the second request. If a response came, then build users names array If a response came, then build products names array The execution inside the core will look like this: Switch to process 1 This conclusion is based on the fact that the slowest request takes 3 seconds, the 2 network calls took 10 milliseconds, and both loops for collecting names each takes 10 milliseconds. The execution time for those two processes will be something like 3.03 seconds (not 100% accurate I know). In that case, our processes will be executed concurrently. In other words, the available cores will switch between processing our two processes and other processes. In that case, the OS will share the CPU time between those processes. However, in most cases there are other processes running on the machine that need to use the available cores. If you have a multi-core processor, we all have now, and there are 2 idle cores sitting around, the OS will use both cores to execute the processes in parallel (at the same time). Running each of these function calls in a separate process gives the operation System the task of running them in parallel.
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