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From Alex Grässer <al...@computicket.com>
Subject [users@httpd] Establishing a new connection sometimes takes long (30s).
Date Tue, 13 May 2008 07:10:18 GMT
Hi
 
We are experiencing an intermittent but reproducible problem, where establishing a new connection
to Apache httpd sometimes takes up to 30 seconds. We are running 350 threads with +-20 threads
in keepalive state (according to /server-stats) and nothing else connecting or executing in
Apache at the time the new connection comes in. There _should_ be a thread available for a
new connection and the socket accept _should_ be listening. What we are seeing is that there
is a pause between when the network card receives the message and Apache gets the message.
In the test we were using a Java HttpConnection but we can reproduce the problem with IE and
Firefox as well. There is no firewall on the machine.

Can anybody please explain why this could be happening or how we can go about finding the
delay.

Thank you
Alexander Grässer

-TRACE------------------------
A case in point (delay of 17 seconds), running Packetyzer 5.0.0 on the network card:
 
13:02:25.249190000 client -> server : SYN (62 bytes)
13:02:25.249224000 server -> client : SYN ACK (62 bytes)
13:02:25.251134000 client -> server : ACK (60 bytes)
13:02:25.251864000 client -> server : HTTP GET (268 bytes)
13:02:25.442069000 server -> client : ACK (54 bytes)
13:02:42.960316000 server -> client : HTTP DATA (1514 bytes)
13:02:42.960327000 server -> client : HTTP continuation (155 bytes)
13:02:42.963080000 client -> server : ACK (60 bytes)
 
and then access.log (using LogFormat "%h %l %u %t \"%r\" %>s %b (%T/%D) \"%{Referer}i\"
\"%{User-Agent}i\"" combined) indicates an execution time of 31,250 milliseconds.

[client-ip] - - [12/May/2008:13:02:42 +0200] "GET /xxxxx/xxxx HTTP/1.1" 200 1310 (0/31250)
"-" "Java(tm) 2 SDK, Standard Edition v1.5.0_10 Java/1.5.0_10"

-CONFIG-------------------------
The config of the system is as follows: (Although we see this on differently configured Win2k
machines as well)
System:
  Microsoft Windows 2000
  5.00.2195
  Service Pack 4
 
Computer:
  Intel(R) Xeon(TM)
  CPU 3.20GHz
  AT/AT Compatible
  2,096,432 KB RAM
 
Disk:
  Device: PERC LD 0 PERCRAID SCSI 6.34 GB (6,810,531,328 bytes) with 842 MB free.
  Driver: Microsoft disk.sys, Version 5.0.2183.1 / 5.00.2195.6655 (11/14/1999)
 
Network:
  Card: Intel(R) PRO/1000 MT
  Driver: Intel e1000nt5.sys, version 7.2.19.0002 (8/2/2004)
  WinSock: 3.10
  WinSock32: 5.00.2195.6603
 
Apache
  Server Version: Apache/2.2.8 (Win32) mod_jk/1.2.26 
  Server Built: Jan 18 2008 00:37:19 
Httpd.conf:
<IfModule mpm_winnt_module>
  ThreadsPerChild 350
  ThreadLimit 350
  ListenBacklog 511
  MaxRequestsPerChild 0
</IfModule>
Timeout 300
KeepAlive On
MaxKeepAliveRequests 100
KeepAliveTimeout 120
HostnameLookups Off


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