Hoping someone can point me in the right direction as I've spent the last week trying to figure out where the "issue" is but haven't been able to, tried posting to the Apache users mailing lists but wanted to bounce it off here as well.
Running Apache 2.2.3 mod_php on CentOS 5.8.
At the same time every day when traffic is heavy we are having an issue where Apache no longer responds to any HTTP requests.
It sounded like a standard MaxClients being reached issue, but that doesn't seem to be the case.
Also, logging into the machine during this time the load average is under 1, and there is still plenty of RAM available.
Reviewing /var/log/httpd/error_log I've noticed the following patterns:
[Mon Apr 30 07:00:34 2012] [info] server seems busy, (you may need to increaseStartServers, or Min/MaxSpareServers), spawning 32 children, there are 0 idle, and 905 total children
[Mon Apr 30 07:00:35 2012] [info] server seems busy, (you may need to increase StartServers, or Min/MaxSpareServers), spawning 32 children, there are 0 idle, and 937 total children
[Mon Apr 30 07:00:36 2012] [info] server seems busy, (you may need to increase StartServers, or Min/MaxSpareServers), spawning 32 children, there are 0 idle, and 969 total children
[Mon Apr 30 07:00:37 2012] [info] server seems busy, (you may need to increase StartServers, or Min/MaxSpareServers), spawning 32 children, there are 35 idle, and 1001 total children
[Mon Apr 30 07:00:42 2012] [debug] mpm_common.c(663): (70007)The timeout specified has expired: connect to listener on [::]:80 <br>
[Mon Apr 30 07:00:49 2012] [debug] mpm_common.c(663): (70007)The timeout specified has expired: connect to listener on [::]:80 <br>
[Mon Apr 30 07:00:56 2012] [debug] mpm_common.c(663): (70007)The timeout specified has expired: connect to listener on [::]:80 <br>
[Mon Apr 30 07:01:03 2012] [debug] mpm_common.c(663): (70007)The timeout specified has expired: connect to listener on [::]:80 <br>
A few times a day, right after 1000 total children
Apache stops responding and has to be restarted in order to work again.
I've reviewed the error_log from a few weeks back and it's the same pattern, the server hits 1000 total children and then immediately spits out the
[debug] mpm_common.c(663): (70007)The timeout specified has expired: connect to listener on [::]:80
error message and stops responding.
Yet the load on the server is quite low... Even if I try and request a simple index.html file it times out.
Here is the relevant section from the config:
Timeout 45
KeepAlive On
MaxKeepAliveRequests 10000
KeepAliveTimeout 3
<IfModule prefork.c>
StartServers 80
MinSpareServers 50
MaxSpareServers 120
ServerLimit 3500
MaxClients 3500
MaxRequestsPerChild 2000
</IfModule>
Anyone know why the magic number of children Apache is able to reach is 1000 before it stops processing more requests?
Or how to make sense of the (70007)The timeout specified has expired: connect to listener on [::]:80
message?
What "timeout specified" is it referring to?
I've double check Max Open Files, it previously was at 1024 but now its at 16384, still the same problem.