PHP

2010年9月15日 — Locking without LOCK_NB is much more persistent and it will wait for the lock for as long as it takes. It is almose guaranteed that the file ...

2016年10月9日 — I like FlockMutex because it work on kernel level and is reliable. however there's the problem that acquiring the lock makes program wait ...

2023年3月13日 — It means that it points to a variable outside the function. It will return the value that was set by flock($handle, $flags, $would_block) .

This means that if the file lock is not available, flock() will return immediately with false rather than hang around waiting for a lock to become available.

2015年7月8日 — By default, this function will block until the requested lock is acquired; this may be controlled with the LOCK_NB option documented below. PHP ...

2013年9月16日 — If you try to acquire an exclusive lock while another process has the file locked, your attempt will wait until the file is unlocked.

LOCK_EX - An exclusive lock (writer). Prevent other processes from accessing the file; LOCK_UN - Release the lock; LOCK_NB - Avoid blocking other processes ...

When the php script started, it checks if the file process_lock is locked or not, if it is not locked, then it starts the process, sleeps for 10 seconds, and ...

* the flock returns immediately instead of waiting indefinitely. *. * @param resource $lockfile Lock file resource that is opened.

if ($file->flock(LOCK_EX)) // do an exclusive lock ... lock is acquired. You also may need fseek(0); to ... sleep(5); // wait for 5 seconds if ($file->flock ...