> Have you checked without the MaxMemFree setting? I raised MaxMemFree to 3100, we will have to wait for a few days, since it does not happen every day.
> Why do you use MaxMemFree with such a small value at all? We are also running 2 twistd server processes on this machine that can take up to 256MB each, so we wanted to leave some room for them. As I understand from the manual, MaxMemFree is not an absolute limit on the memory available to Apache anyway, it just asks it to release *unused* memory with free() call after it reaches MaxMemFree value? > -----Original Message----- > From: Ruediger Pluem [mailto:[EMAIL PROTECTED] > Sent: Monday, October 01, 2007 1:23 AM > To: dev@httpd.apache.org > Subject: Re: 2.0.54 unstable, requests time-out, NO warnings in logs > > > > On 10/01/2007 08:32 AM, Alec Matusis wrote: > > We are running a busy Apache/2.0.54 server on 2.6.9 kernel, that > suddenly becomes very slow- requests either time out, or it takes 10- > 20sec to serve a 1K thumbnail. > > It is somewhat correlated with load spikes, but not perfectly (by > looking at the bandwidth graph, it never happens during the low > bandwidth periods at night, but it does not coincide with peaks of b/w) > > > > When we initially encountered an apache overload, it was always > accompanied with > > > > [error] server reached MaxClients setting, consider raising the > MaxClients setting > > > > in the apache error log. We also got > > > > kernel: possible SYN flooding on port 80. Sending cookies. > > > > in /var/log/messages system log. > > > > After that I raised MaxClients from 200 to 300. The problem initially > disappeared, but after our bandwidth grew a bit more, we got this > behavior again. > > Now apache crashes (becomes very slow) silently, with no warning in > apache error logs at all (although we still get SYN flood message in > the system log) > > When apache is this 'slow' regime, /server-status still shows > available slots, i.e. MaxClients is not reached. > > > > This is the relevant part of httpd.conf: > > > > ServerLimit 300 > > # we are using prefork MPM > > StartServers 10 > > MinSpareServers 5 > > MaxSpareServers 20 > > MaxClients 300 > > MaxRequestsPerChild 10000 > > MaxMemFree 2500 > > > > The server has 4GB of physical RAM and 4GB of swap. During these > apache slowdowns", the swap size is still 0 and vmstat shows no > swapping at all. > > I suspect the problem may be in > > > > MaxMemFree 2500 > > Have you checked without the MaxMemFree setting? > Why do you use MaxMemFree with such a small value at all? > > Regards > > Rüdiger
