ID: 31363 Comment by: maurice at gitaar dot net Reported By: ian at snork dot net Status: Open Bug Type: Filesystem function related Operating System: Debian woody (i386) PHP Version: 5CVS-2005-03-09 New Comment:
I had the same problem. It seems that errno is not reset to zero in the flock implementation. Therefore the last errno will be used. In case no other errno-modifying call is made before retrying the flock() call, the call will conclude in an EWOULDBLOCK situation (my conclusion after a very quick scan of the code). Looking with truss on Solaris to the process shows that the first fcntl call (during which I have already locked the file) returns an EAGAIN error, meaning that the file was already locked. The second fnctl call (on the now unlocked file) does not return an error. So the call is successfull. But the call from the php code does set the $wouldblock parameter to a true value. For me a workaround for now is something like this (no error checking on flock and a bit of pseudo-coded, but the workaround is the important part): for (;;) { flock($fd, LOCK_EX|LOCK_NB, $wouldblock); if (! $wouldblock) break; fopen("/this/is/no/real/file", "r"); } The fopen() call sets errno to the file not found error, which makes the flock() call act like the first time it is called. This is not great coding, but it does work for me till a real fix is implemented in PHP. Previous Comments: ------------------------------------------------------------------------ [2005-04-01 14:42:19] maka3d at yahoo dot com dot br I expected it to be fixed until 5.0.4. On freeBSD it doesn't work too :( ------------------------------------------------------------------------ [2005-03-09 17:29:56] ian at snork dot net flock() in today's PHP CVS snapshot (http://snaps.php.net/php5-latest.tar.bz2) behaves slightly differently, but still doesn't quite work correctly in non-blocking mode. Expected result: -------------- $ php5 flock_test.php & Got /tmp/test1 $ php5 flock_test.php & Got /tmp/test2 $ php5 flock_test.php & Got /tmp/test3 $ php5 flock_test.php & $ Releasing /tmp/test1 Got /tmp/test1 Releasing /tmp/test2 Releasing /tmp/test3 Actual result: -------------- $ php5 flock_test.php & Got /tmp/test1 $ php5 flock_test.php & Got /tmp/test2 $ php5 flock_test.php & Got /tmp/test3 $ php5 flock_test.php & $ Releasing /tmp/test1 Releasing /tmp/test2 Releasing /tmp/test3 ------------------------------------------------------------------------ [2005-02-28 21:06:39] [EMAIL PROTECTED] Please try using this CVS snapshot: http://snaps.php.net/php5-latest.tar.gz For Windows: http://snaps.php.net/win32/php5-win32-latest.zip ------------------------------------------------------------------------ [2004-12-31 06:41:56] ian at snork dot net Description: ------------ This code works in PHP 4.3.0, but does not in PHP 5.0.3. When invoked, it will try to lock /tmp/test1, /tmp/test2 or /tmp/test3 for exclusive use, whichever is free. If none are, it will wait a second before cycling through with another attempt. When running concurrently, the first invocation correctly picks up /tmp/test1; the second and subsequent ones just cycle forever. For some reason, the non-blocking flock() only sets $block the first time. Reproduce code: --------------- while (!sleep(1)) foreach (array("/tmp/test1", "/tmp/test2", "/tmp/test3") as $path) if (flock($handle = fopen($path, "w"), LOCK_EX | LOCK_NB, $block) and !$block) { echo "Got $path\n"; sleep(10); echo "Releasing $path\n"; exit; } Expected result: ---------------- $ php5 flock_test.php & Got /tmp/test1 $ php5 flock_test.php & Got /tmp/test2 $ php5 flock_test.php & Got /tmp/test3 $ php5 flock_test.php & Releasing /tmp/test1 Got /tmp/test1 $ Actual result: -------------- $ php5 flock_test.php & Got /tmp/test1 $ php5 flock_test.php & $ php5 flock_test.php & $ php5 flock_test.php & $ ------------------------------------------------------------------------ -- Edit this bug report at http://bugs.php.net/?id=31363&edit=1