Bug #49383 [Bgs]: Lots of empty fstat() calls slow performance

Edit report at http://bugs.php.net/bug.php?id=49383&edit=1 ID: 49383 Updated by: rasmus@php.net Reported by: olga at metacafe dot com Summary: Lots of empty fstat() calls slow performance Status: Bogus Type: Bug Package: Performance problem Operating System: Red Hat 3.4.6-10 PHP Version: 5.3, 6 Block user comment: N New Comment: Do you have openbase_dir enabled? If so, for security reasons we can't use the stat cache which is going to cause a lot of stats. For a setup with slow stats, I suggest chroot/jail or something along those lines rather than open_basedir to keep users separated. Previous Comments: ------------------------------------------------------------------------ [2010-08-11 20:10:56] a dot rogge at solvention dot de Nobody cares wether or not APC works around the problem. There is obviously a regression from 5.2 to 5.3. Somebody maanged to triple the number of fstat() calls that are done for an include(). Yesterday I "reproduced" the issue on our webcluster. Running the Red Hat provided PHP 5.1.6 (from RHEL 5.5) the loadavg was around 8 for all boxes. Upgrading to PHP 5.3.2 made the loadavg raised to values of 30 or higher. Page load time went from < 1 second to around 30 seconds. The best part is: we did install and configure apc for 5.3.2, but not for 5.1.6 So eventually 5.3.2 *with* APC produces 3 times more load and needs 30 times longer than our ancient 5.1.6 *without* APC. However, I must admit that we have our PHP-files on GFS2 where stat() is traditionally a bit slow. ------------------------------------------------------------------------ [2010-01-21 23:16:42] rasmus@php.net Unable to reproduce under apc. ------------------------------------------------------------------------ [2009-10-14 11:28:06] olga at metacafe dot com The problem persists. We upgraded APC to the latest version (3.1.3p1). Cache full count is 0, hit ratio is 99.9%. I understand that this shouldn't happen, but there are still 3 fstat() calls per file opened. Here's our APC configuration - maybe you can see if anything is wrong with it? Do you have other versions? apc.cache_by_default 1 apc.canonicalize 1 apc.coredump_unmap 0 apc.enable_cli 1 apc.enabled 1 apc.file_md5 0 apc.file_update_protection 2 apc.filters apc.gc_ttl 3600 apc.include_once_override 1 apc.lazy_classes 0 apc.lazy_functions 0 apc.max_file_size 1M apc.mmap_file_mask /tmp/apc.IR76ZW apc.num_files_hint 1024 apc.preload_path apc.report_autofilter 0 apc.rfc1867 0 apc.rfc1867_freq 0 apc.rfc1867_name APC_UPLOAD_PROGRESS apc.rfc1867_prefix upload_ apc.rfc1867_ttl 3600 apc.shm_segments 1 apc.shm_size 128 apc.stat 0 apc.stat_ctime 0 apc.ttl 7200 apc.use_request_time 1 apc.user_entries_hint 4096 apc.user_ttl 7200 apc.write_lock 1 ------------------------------------------------------------------------ [2009-09-03 16:49:18] rasmus@php.net The only time this code is executed if you are running APC is if the script is not cached. So, either your APC setup is not working, you are constantly trashing your cache (check apc.php and look at the cache-full counter), or something else weird is going on. These fstats are coming from compiler which reads the script from disk and compiles it down to opcodes. It is impossible for this code to execute on an APC-cached script because we point the executor directly at the already compiled opcodes in shared memory. ------------------------------------------------------------------------ [2009-09-03 15:06:28] olga at metacafe dot com Thanks for the quick response. We do work with APC. I tested the new PHP without APC also, to make sure the fstat() calls aren't caused by it. But the statistics I sent to you are from web server that works with APC. You can also see from my first submission that in 5.2.9 fstat() doesn't take much time. ------------------------------------------------------------------------ The remainder of the comments for this report are too long. To view the rest of the comments, please view the bug report online at http://bugs.php.net/bug.php?id=49383 -- Edit this bug report at http://bugs.php.net/bug.php?id=49383&edit=1