On Thu, Apr 15, 2010 at 9:09 AM, Ferenc Kovacs <tyr...@gmail.com> wrote:
> > > 2010/4/15 Jérôme Loyet <jer...@loyet.net> > > 2010/4/15 滕路遥 <tly.phpf...@gmail.com>: >> > We check error log after our server crashed, and we found that php heap >> > memory is out of limit, >> > so I think imagick use emalloc to allocate php heap memory, to check the >> > zend_memory_usage is >> > not a method for imagick, other circumstances which occupy huge memory >> can >> > use this method to >> > ensure the system have enough free memory. >> >> OK, >> >> one thing I didn't understand is "why should you want check de zend >> memory usage when there is a memory_limit parameter in PHP.ini " ? >> does'nt it do the same at PHP layer when allocating ? >> >> > Obviously you didn't read the original mail, and the links inside: > > > http://groups.google.com/group/highload-php-en/browse_thread/thread/1882a3b2257dcc5c/ea73892cea011541?lnk=gst&q=gaochunhui#ea73892cea011541 > > The problem here is that PHP wouldn't free any allocated memory untill > the process exits, so there's the risk of memory exhaustion if too > many PHP processes were running, even though each process wouldn't > exceed PHP's memory_limit. > > My suggestion is more about releasing the allocated memory as soon as > possible. That is, this option is similar to "max_requests". > PHP-FPM would kill the PHP process if the requests a process handled > exceed max_requests, and similarly, PHP-FPM should kill the PHP > process whose memory usage exceeds "exit_on_memory_exceeds". > > So one of your lib (for example imagick) leaks memory, on the long run, it > will exhaust the memory limit, and will kill a totaly request. > You can set that how many request should be served with one worker, but you > can't soft limit it's memory consumption. > This is what the patch does: > if you set the hard limit: (memory_limit) you can guarante that no process > will use more memory, because if it tries, it will fail. > and you can set soft limit, if that reached, the process will die and > respawn after finishing the current request. > > Tyrael > Btw: did you know about http://php.net/manual/en/function.apache-child-terminate.php I just noticed a few days ago, obviously, you can't use with cgi/fastcgi/php-fpm but for apache, it does exactly what you need, except that you have to execute from userland. So I think it would be a good idea, to generally implement a soft/hard limit for memory allocation: if soft fails, the process terminates after the request, if the hard limit fails, it is terminated instantly. Tyrael
