PHP implements file locking to solve the problem of multiple processes reading and writing a file at the same time

This article mainly introduces PHP's method of solving the problem of simultaneous reading and writing of a file by multiple processes based on file locks. It analyzes the usage of PHP using flock to read, write and lock files in the form of examples. Friends who need it can refer to it

The details are as follows:

First of all, PHP supports processes but does not support multi-threading (clarify this first). If it is a file operation, in fact, you only need to lock the file to solve the problem. If other operations are needed, PHP flock has already done it for you.

Use flock to lock the file before writing, and unlock it after writing. This allows multiple threads to read and write a file at the same time to avoid conflicts. Probably the following process

/*
*flock(file,lock,block)
*file 必需，规定要锁定或释放的已打开的文件
*lock 必需。规定要使用哪种锁定类型。
*block 可选。若设置为 1 或 true，则当进行锁定时阻挡其他进程。
*lock
*LOCK_SH 要取得共享锁定（读取的程序）
*LOCK_EX 要取得独占锁定（写入的程序）
*LOCK_UN 要释放锁定（无论共享或独占）
*LOCK_NB 如果不希望 flock() 在锁定时堵塞
/*
if (flock($file,LOCK_EX))
{
fwrite($file,'write more words');
flock($file,LOCK_UN);
}
else
{
//处理错误逻辑
}
fclose($file);
)

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