Apache httpd using all memory till server down

Question

I have a server Intel(R) Xeon(R) CPU X3440 with 8GB RAM.
From what I see that the Apache using all the RAM and make the server unresponsive.

Here is my Apache Configuration:

<IfModule prefork.c>
StartServers       8
MinSpareServers    5
MaxSpareServers   20
ServerLimit      1000
MaxClients       1000
MaxRequestsPerChild  4000
</IfModule>

And this is my free -m:

         total       used       free     shared    buffers     cached
Mem:      7859       7725        134          0        189       1566
-/+ buffers/cache:   5969       1889
Swap:     4095         61       4034

And this is my TOP :

top - 10:19:57 up 23 min,  1 user,  load average: 8.08, 6.50, 3.90
Tasks: 1124 total,   1 running, 1123 sleeping,   0 stopped,   0 zombie
Cpu(s):  9.8%us,  3.2%sy,  0.1%ni, 60.0%id, 26.2%wa,  0.0%hi,  0.6%si,  0.0%st
Mem:   8048096k total,  7924168k used,   123928k free,   207920k buffers
Swap:  4194300k total,    79820k used,  4114480k free,  1460356k cached

PID USER      PR  NI  VIRT  RES  SHR S %CPU %MEM    TIME+  COMMAND
1921 mysql     20   0 1653m  39m 3428 S 62.7  0.5   6:26.24 mysqld
7944 apache    20   0  399m  29m 4236 S  6.6  0.4   0:10.13 httpd
3201 apache    20   0  382m  11m 3880 S  2.3  0.1   0:00.50 httpd
8030 apache    20   0  382m  10m 3872 S  2.0  0.1   0:00.39 httpd
2837 apache    20   0  384m  13m 3916 S  1.3  0.2   0:00.37 httpd
3160 apache    20   0  383m  11m 3908 S  1.3  0.2   0:00.55 httpd
10555 apache    20   0  382m  11m 3884 S  1.3  0.1   0:00.48 httpd
13626 apache    20   0  381m  10m 3828 S  1.3  0.1   0:00.05 httpd
13668 apache    20   0  382m  11m 3760 S  1.3  0.1   0:00.16 httpd
14284 apache    20   0  381m  10m 3712 S  1.3  0.1   0:00.06 httpd
2848 apache    20   0  382m  11m 3876 S  1.0  0.2   0:00.49 httpd
5254 apache    20   0  382m  11m 3852 S  1.0  0.1   0:00.25 httpd
6085 apache    20   0  382m  10m 3768 S  1.0  0.1   0:00.26 httpd
6257 apache    20   0  382m  11m 3876 S  1.0  0.1   0:00.50 httpd
8067 apache    20   0  380m 9.8m 3732 S  1.0  0.1   0:00.18 httpd
14314 apache    20   0  382m  10m 3768 S  1.0  0.1   0:00.09 httpd
14328 apache    20   0  380m 9288 3800 S  1.0  0.1   0:00.16 httpd

So what is the recommends to solve this problem?

Answer 1

I just answered a similar question Check this link. Here's what I suggested:

I had a similar problem with an instance in EC2 and here's what I did and would suggest:

1. If you are using prefork, make sure that the module is loaded by typing these two commands httpd -l and sudo httpd -M If you can see the prefork module loaded in the results of either of these two commands then up to the next step. Otherwise, make sure to load it first or else you would be changing the configurations for nothing.

2. Run this command to find the average memory each httpd process is using ps aux | grep 'httpd' | awk '{print $6/1024;}' | awk '{avg += ($1 - avg) / NR;} END {print avg " MB";}' Call that value x

3. Restart your apache server by using sudo service httpd restart and take a note of how much free memory you have. What I did was subtract an extra 200MB-500MB cushion from that free memory to be used later. Call that value y

4. Divide the value of free memory y over the amount of memory used per process x and that would be the value of MaxRequestWorkers = y/x

5. As for the value of MaxConnectionsPerChild then you can tweak it till you get the right configuration. It you make it too big, then the process will keep using more and more memory before being killed. If you make it too small, then the processes will die too quickly and that will present an overhead on your system. I usually keep it somewhere between 4000 and 10000.

6. Some of these steps have been taken from the accepted answer in the following link: StackExchange: httpd memory usage where one solution also suggested disabling some of the modules if you don't need them.

7. Make sure to check the access logs. May be someone is trying to attack your website!

I would suggest you do steps 1-5 first and see if that solves your problem!

Good luck!