How to restart swoole

In swoole, we can send various signals to the main process, and the main process will perform different processing according to the type of signal received.

For example, the following ones (recommended learning: swoole video tutorial)

1、kill -SIGTERM|-15 master_pid  终止Swoole程序,一种优雅的终止信号，会待进程执行完当前程序之后中断，而不是直接干掉进程
2、kill -USR1|-10  master_pid  重启所有的Worker进程
3、kill -USR2|-12  master_pid  重启所有的Task Worker进程

When the USR1 signal is sent to the Master process, the Master process will send the same The signal is forwarded to the Worker process through the Manager process. The Worker process that receives this signal will release the process memory after processing the logic being executed, shut down itself, and then the Manager process will restart a new Worker process.

The new Worker process will occupy new memory space.

Scenario:

If it is an online project, a busy back-end server is processing requests at any time. If the administrator terminates/restarts the process by killing it Server programs may cause the code to terminate in the middle of execution.

In this case, data inconsistency will occur.

For example, in a trading system, the next section of the payment logic is shipment. It is assumed that the process is terminated after the payment logic. This will cause the user to pay the currency but not deliver the goods, and the consequences will be very serious.

swoole provides us with a smooth restart mechanism. We only need to send a specific signal to the main process of swoole_server to complete the restart of the server.

Notes:

1. The update is only for the worker process. Include in the worker process means writing the update code in the master process and manager process. It does not take effect, which means that restarting is only meaningful for files loaded after the onWorkerStart callback.

A file that has been loaded into the memory before the Worker process is started. If you want it to take effect again, you can only close the server and restart it.

2. Logic written directly in the worker code will not take effect, even if a signal is sent. Relevant business logic code needs to be introduced through include to take effect

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