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Having a web-server (don't know actually whoset it up, it's my heritage). Few hours ago it started working very (extremely!) slow, mysqld oftenly fails requests.
/var/log/mysqld.log is empty (well, it says, mysqld started, and so on, but nothing regarding today)
/var/log/apache2/access_log is full of such lines:

::1 - - [30/Nov/2011:10:15:05 +0100] "GET / HTTP/1.0" 200 1 "-" "Apache/2.2.3 (Linux/SUSE) (internal dummy connection)"
::1 - - [30/Nov/2011:10:15:05 +0100] "GET / HTTP/1.0" 200 1 "-" "Apache/2.2.3 (Linux/SUSE) (internal dummy connection)"
::1 - - [30/Nov/2011:10:15:05 +0100] "GET / HTTP/1.0" 200 1 "-" "Apache/2.2.3 (Linux/SUSE) (internal dummy connection)"
::1 - - [30/Nov/2011:10:15:05 +0100] "GET / HTTP/1.0" 200 1 "-" "Apache/2.2.3 (Linux/SUSE) (internal dummy connection)"
::1 - - [30/Nov/2011:10:15:05 +0100] "GET / HTTP/1.0" 200 1 "-" "Apache/2.2.3 (Linux/SUSE) (internal dummy connection)"
::1 - - [30/Nov/2011:10:15:05 +0100] "GET / HTTP/1.0" 200 1 "-" "Apache/2.2.3 (Linux/SUSE) (internal dummy connection)"
::1 - - [30/Nov/2011:10:15:05 +0100] "GET / HTTP/1.0" 200 1 "-" "Apache/2.2.3 (Linux/SUSE) (internal dummy connection)"
::1 - - [30/Nov/2011:10:15:05 +0100] "GET / HTTP/1.0" 200 1 "-" "Apache/2.2.3 (Linux/SUSE) (internal dummy connection)"
::1 - - [30/Nov/2011:10:15:05 +0100] "GET / HTTP/1.0" 200 1 "-" "Apache/2.2.3 (Linux/SUSE) (internal dummy connection)"
::1 - - [30/Nov/2011:10:15:05 +0100] "GET / HTTP/1.0" 200 1 "-" "Apache/2.2.3 (Linux/SUSE) (internal dummy connection)"
::1 - - [30/Nov/2011:10:15:05 +0100] "GET / HTTP/1.0" 200 1 "-" "Apache/2.2.3 (Linux/SUSE) (internal dummy connection)"
::1 - - [30/Nov/2011:10:15:05 +0100] "GET / HTTP/1.0" 200 1 "-" "Apache/2.2.3 (Linux/SUSE) (internal dummy connection)"
::1 - - [30/Nov/2011:10:15:05 +0100] "GET / HTTP/1.0" 200 1 "-" "Apache/2.2.3 (Linux/SUSE) (internal dummy connection)"

Guys, what's that? How to heal this? I read internal dummy connections happen sometimes, but sending internal requests at 1000/sec frequency isn't freaking normal!

How to find out the reason of this?

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Do you have some funky rewrite / proxying rules in place? –  Janne Pikkarainen Dec 1 '11 at 9:40
    
Guess no. Actually that server was up for some months from my last changings –  Dmitry Dec 1 '11 at 9:55

1 Answer 1

The Apache Wiki's InternalDummyConnection article describes why these requests are issued, though there is definitely something wrong if no Apache configuration or application changes have been made prior to this behavior's appearance.

If you are using Apache v2.2.6, (please detail apache2ctl -V) Bug# 39653 (and related comments) may be of interest:

I have a suspicion that this bug caused my apache to spawn 150 processes (as many as MaxClients would allow), thus repeatedly crashing the server (once per day).

This bug makes about one request per second, I suspect causing apache to spawn multiple instances, although I don't know why it would spawn as many as MaxSpareServers and not as many as MaxClients right away.

If you have a database-backed application responding to these requests, it may be advisable to apply a conditional (either in your Apache configuration or in the application itself) which either diverts requests (or skips default application behavior) when the requests originate from the 127.0.0.1 or ::1 loopback addresses.

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Server version: Apache/2.2.3 Think, it has the same bug too? Well, I think I'll create rewriterule condition: this will be the temporal solution... But it's not the solution at all. –  Dmitry Dec 1 '11 at 10:31
    
This is not the exact issue described in the linked bug report, though - until the root of the problem is determined - is the mysqld crash resolved when you divert requests from loopback addresses (or handle requests from loopback addresses by halting processing in your application) ..? –  danlefree Dec 1 '11 at 10:35

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