The situation is this: Apache on our main dynamic web server keeps on suddenly eating all 3+GB of available virtual memory. When this happens, the server stops responding to all requests, and basically freezes until the kernel OOM killer gets around to killing enough httpd processes so we can get in to kill the rest and restart it. This happens every couple of minutes to couple of hours - there's no pattern to it. You can see an attractive graph of the occurence here:
http://static.last.fm/phpbug/mem.gif
As you can see, the memory usage shoots up suddenly - it doesn't appear to be a conventional memory leak. This is accompanied by a similar spike in the number of apache processes - right up to the MaxClients limit.
We've been running PHP with debug support enabled for the last couple of days, and we've noticed that a series of errors is always logged just before the spike in memory usage. A log snippet is available here (note that these errors carry on for several pages - although I suspect the first one is the only relevant one - this is only the first page or so):
http://static.last.fm/phpbug/log.txt
The error doesn't just happen with that script, however the initial error always occurs in the same place (zend_variables.c:44).
This machine serves around 500,000 hits daily, and 99% of them are PHP-parsed. It's running Debian 3.0 with backported kernel 2.6.7. The bug manifests itself with both Apache 1.3 and 2, and both PHP 4.3.8 and 4.3.9RC2. Compile options are as follows:
'./configure' '--with-apxs2=/web/apache2/bin/apxs' '--without-mysql' '--with-zlib-dir=/usr' '--enable-gd-native-ttf' '--with-gettext' '--enable-mbstring' '--with-pgsql=/usr/local/pgsql' '--enable-sysvmsg' '--with-gd' '--with-jpeg-dir=/usr' '--enable-debug'
The only third-party module we're using is Turck mmcache - removing it is kind of difficult since running without any cache brings the machine to its knees :).
Sorry about the length of this message, I had to fit all the details in... I'd appreciate it if you have any suggestions at all, this is really annoying me now. It's problems like this with PHP which make me consider moving to Java ;)... Anyhow.
Thanks in advance,
Russ Garrett [EMAIL PROTECTED]
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