| 1 |
On Sun, Sep 16, 2012 at 9:26 AM, Michael Hampicke <gentoo-user@××××.biz> wrote: |
| 2 |
> Am 16.09.2012 08:55, schrieb Jarry: |
| 3 |
>> Hi, |
| 4 |
>> strange thing happened to my web-server (apache-2.2.22-r1): |
| 5 |
>> it started forking untill it used all ram/swap and stopped |
| 6 |
>> responding. I counted ~60 apache processes running (ps -a), |
| 7 |
>> all sleeping, top showed no load except all memory being used. |
| 8 |
>> Log-files showed nothing suspicious to me, except for a few |
| 9 |
>> "GET / HTTP/1.1 200 40" messages at the time when apache |
| 10 |
>> was already unable to send reply. |
| 11 |
>> |
| 12 |
>> Apparently my apache is not correctly configured when it |
| 13 |
>> "forked to death", but maybe someone can help me. I have |
| 14 |
>> about 1GB memory for apache. What should I change in my |
| 15 |
>> config so that apache never runs out of memory? |
| 16 |
>> |
| 17 |
>> server-info: |
| 18 |
>> Timeouts: connection: 60 keep-alive: 15 |
| 19 |
>> MPM Name: Prefork |
| 20 |
>> MPM Information: Max Daemons: 150 Threaded: no Forked: yes |
| 21 |
>> Module Name: prefork.c |
| 22 |
>> 31: StartServers 5 |
| 23 |
>> 32: MinSpareServers 5 |
| 24 |
>> 33: MaxSpareServers 10 |
| 25 |
>> 34: MaxClients 150 |
| 26 |
>> |
| 27 |
>> Jarry |
| 28 |
>> |
| 29 |
> |
| 30 |
> |
| 31 |
> Hi, |
| 32 |
> |
| 33 |
> try reducing MaxClients to 64, StartServers and MinSpareServers to 2 and |
| 34 |
> then observe how things develop. If you then feel apache is to slow to |
| 35 |
> respond to request under load, try increasing MinSpareServer one at a |
| 36 |
> time. But always keep in mind: every fork of apache eats your memory. |
| 37 |
|
| 38 |
And sucks up system entropy. And increases connection latency, if |
| 39 |
you've already got a request waiting on that fork to spin up. |
| 40 |
|
| 41 |
I have StartServers, MinSpareServers, MaxSpareServers and MaxClients |
| 42 |
all pegged to the same value. And on the server in question, they'll |
| 43 |
all pegged to '10'. |
| 44 |
|
| 45 |
I have MaxRequestsPerChild set to 20000, so that any leaky processes |
| 46 |
get cleaned up. |
| 47 |
|
| 48 |
Because I need to fit a lot of operation into a limited space, I need |
| 49 |
to be able to reasonably predict how much RAM is going to be in use by |
| 50 |
each of my services. A "MaxClients" of 10 may seem small, but that's |
| 51 |
what Squid is for; only requests Squid couldn't cache get passed on to |
| 52 |
Apache. |
| 53 |
|
| 54 |
The server I'm describing is a VM with 4GB of RAM, and is also running |
| 55 |
MySQL, squid and memcached. For those playing with the numbers in |
| 56 |
their head, each of these numbers reflect RES (code+data resident in |
| 57 |
RAM): |
| 58 |
|
| 59 |
* Each Apache process is consuming 80-100MB of RAM. |
| 60 |
* Squid is consuming 666MB of RAM |
| 61 |
* memcached is consuming 822MB of RAM |
| 62 |
* mysqld is consuming 886MB of RAM |
| 63 |
* The kernel is using 110MB of RAM for buffers |
| 64 |
* The kernel is using 851MB of RAM for file cache (which benefits squid). |
| 65 |
|
| 66 |
And, not RAM, but potentially of interest for the curious: |
| 67 |
* The MySQL db is consuming 3.8GB on disk. |
| 68 |
* The Squid cache is about 9.2GB on disk. |
| 69 |
|
| 70 |
|
| 71 |
-- |
| 72 |
:wq |
Archives