process
A process is a running activity of a program on a certain data set in a computer. It is the basic unit of the system for resource allocation and scheduling, and is the basis of the operating system's machine structure.
Narrow definition: A process is an instance of a running program.
multi-Progress
At the same time, there are two or more programs running in the same operating system.
PHP multi-process
PHP provides a process control extension PCNTL.
PCNTL implements Unix-style process creation, program execution, signal processing, and process termination.
Combine the POSIX series of functions to gain more system bottom-level capabilities.
Install PCNTL, shmop
Turn on --enable-pcntl --enable-shmop in the PHP compilation options.
POSIX is a built-in extension that does not need to be installed.
verification
php -m Check whether there are pcntl and shmop in the PHP module.