What does swoole coroutine mean?

Swoole coroutine is a more lightweight thread. A thread can have multiple coroutines. The coroutine is executed in the thread. It is mainly used to convert the competitive resources in the thread into cooperative operation. It is suitable for For handling IO-intensive tasks.

The operating environment of this tutorial: Windows10 system, Swoole4 version, DELL G3 computer

What does swoole coroutine mean

First, let’s talk about coroutines and understand what they are used for and what are their characteristics.

Coroutines are a more lightweight existence than threads. Just as a process can have multiple Like threads, a thread can have multiple coroutines. Coroutines have the following characteristics

• User mode execution, completely controlled by the program, not managed by the operating system kernel

• Applicable For processing IO-intensive tasks, I will not introduce in detail what an IO-intensive task is here. It is mainly different from CPU-intensive tasks.

• Converts competition resources in threads into Collaborative operation

• Communication between coroutines through channels

• A small amount of context switching overhead, mainly running on threads , in contrast, the context switching of the process is stored in the stack resource, while the coroutine is asynchronous and non-blocking, which is equivalent to the queue task in the user mode thread. It only needs to use the channel as a callback, and there is no need to wait twice after the task is completed. Resource grabbing

Coroutines can be simply understood as threads, but this thread is in user mode and does not require the participation of the operating system. The cost of creation, destruction and switching is very low, unlike threads. Coroutines cannot take advantage of multi-core CPUs. If you want to take advantage of multi-core CPUs, you need to rely on Swoole's multi-process model.

Simply put, coroutines are a kind of collaborative lightweight threads implemented by programmers hosted under threads to achieve lighter concurrency

As the number of programmers increases, the boss It has also continued to grow explosively. Of course, some people have begun to think that threads are not easy to use, so what should we do? Of course, based on the concept of threads, we will implement a set of lightweight threads that are lighter and better to cheat stars ( In fact, coroutines cannot be completely considered threads, because a thread can have multiple coroutines)

The difference between coroutines and threads

Essence

Thread kernel state

Coroutine user state

Scheduling method

The scheduling method of threads is system scheduling. Commonly used scheduling strategies include time-sharing scheduling and preemptive scheduling. To put it bluntly, the scheduling of threads is completely out of your control

The scheduling method of coroutines is collaborative scheduling and is not controlled by the kernel and is switched by free policy scheduling

Recommended learning: swoole tutorial

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