The role of php multi-threading and multi-process

Multiple processes(Recommended learning:PHP video tutorial)

Use multi-process, after the child process ends, the kernel Will be responsible for recycling resources

When using multiple processes, the abnormal exit of the child process will not cause the entire process Thread to exit, and the parent process will have the opportunity to rebuild the process.

A resident main process is only responsible for task distribution, and the logic is clearer.

The multi-process method is more stable, and data sharing can also be achieved using inter-process communication (IPC).

Shared memory, this method is the same as reading and writing variables between threads. It needs to be locked, and there will be synchronization and deadlock problems.

Message queue, you can use multiple sub-processes to grab the queue mode, the performance is very good

Multi-threading

Threads are in the same process, Memory variables can be shared to achieve inter-thread communication

Threads are more lightweight than processes. Opening a large number of processes will consume more system resources than threads

There are also some problems with multi-threading:

There is a synchronization problem when threads read and write variables, and locks are required

If the granularity of the lock is too large, there will be performance problems, which may result in only one thread running and other threads waiting for the lock

Use multiple locks at the same time, the logic is complex. Once a lock is not released correctly, a thread deadlock may occur

A fatal error in a thread will cause the entire process to crash

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