Does the swoole coroutine belong to a process or a thread?

Swoole coroutine belongs to threads. Coroutines are executed in threads. Coroutines are lightweight threads. The underlying implementation of Swoole's coroutines is single-threaded. Only one coroutine is working at the same time, and the threads will be scheduled by the operating system to multiple CPUs. Parallel execution.

The operating environment of this tutorial: Windows 10 system, Swoole 4 version, DELL G3 computer

Is the swoole coroutine a process or a thread?

What is a process?

A process is a program that is running in the system. Once the program is running, it is a process.

A process can be seen as an instance of program execution.

Tags: One process cannot access the variables and data structures of another process. If you want one process to access the resources of another process, you need to use inter-process communication, such as pipes, files, sockets, etc.

What is a thread?

Threads belong to processes and are the executors of programs.

A process contains at least one main thread, and can also have more sub-threads. Each thread uses the stack space of the process to which it belongs.

A thread is an entity of the process and an execution path of the process.

Tags: Multiple threads in the same process will share part of the state, and multiple threads can read and write the same memory.

What is a coroutine?

Coroutines are relatively abstract. They are a certain scheduling mechanism within the program;

Coroutines are lightweight threads. The creation, switching, suspension, and destruction of coroutines are all performed in memory. Operation, consumption is very low.

Coroutines belong to threads, and coroutines are executed in threads.

The scheduling of coroutines is manually switched by the user, so it is also called user space thread.

The scheduling strategy of coroutines is: collaborative scheduling.

The difference between coroutines and threads:

Swoole's coroutine is single-threaded in the underlying implementation, so only one coroutine is working at the same time. Execution is serial. This is different from threads. Multiple threads will be scheduled by the operating system to multiple CPUs for parallel execution.

When one coroutine is running, other coroutines will stop working. The current coroutine will hang when performing blocking IO operations, and the underlying scheduler will enter the event loop. When there is an IO completion event, the underlying scheduler resumes the execution of the coroutine corresponding to the event.

The utilization of CPU multi-core still relies on the multi-process mechanism of the Swoole engine.

Applicable scenarios for coroutines:

Highly concurrent services, such as flash sale systems, high-performance API interfaces, and RPC servers, use coroutine mode, and the fault tolerance rate of the service will increase Greatly increased, when some interfaces fail, the entire service will not collapse.

Crawler can achieve very huge concurrency capabilities, and can efficiently utilize bandwidth even in a very slow network environment.

Instant messaging services, such as IM chat, game server, Internet of Things, message server, etc., can ensure that message communication is completely non-blocking and each message packet can be processed instantly.

Recommended learning: swoole tutorial

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