Hello.
On http://php.net/manual/en/function.flock.php is written a warning:
" On some operating systems *flock()* is implemented at the process
level. When using a multithreaded server API like ISAPI you may not be
able to rely on *flock()* to protect files against other PHP scripts
running in parallel threads of the same server instance! ... "
I do not understand what means that flock is implmented at the process
level.
Does it mean following?:
If in one process in one thread is called flock($fp, LOCK_EX) , in the
second thread flock($fp, LOCK_EX) won't block. $fp are the same in both
calls and flock(.) in the second thread is called before flock(.,
LOCK_UN) from the first thread.
I made a test on Windows 2008 R2, ISS, php 5.3 FastCGI.
I tried even 4 concurrent requests and I think it is working (flock
blocks as expected). I found out that for each GET request it was
created a seperate process php-cgi.exe. So the assumption for this
warning even will not occure.
I made a second test on Windows 2008 R2, Apache, php 5.3 as a module.
In this scenario flock also works. And all GET requests were handled by
the same process.
Can someone confirm that it is safe to use flock on Windows/IIS+FastCGI
and Windows/Apache(multithread)+php(module) ?
Jan.
