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From Apache Wiki <wikidi...@apache.org>
Subject [Jmeter Wiki] Update of "RobinWilson" by RobinWilson
Date Mon, 19 Dec 2011 16:44:26 GMT
Dear Wiki user,

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The "RobinWilson" page has been changed by RobinWilson:
http://wiki.apache.org/jmeter/RobinWilson?action=diff&rev1=8&rev2=9

  
  === NOTES on "strange pause" during testing run ===
  
- Test conditions:
+ When testing a fairly simple HTTP(S) 'registration' process, enabling the "Retrieve All
Embedded Resources" flag for the HTTP Samplers caused an unexpected 'pause' (~35 seconds in
duration) to be regularly added to the test cycle. The addition of the "Retrieve All Embedded
Resources" flag caused the test to increase the amount of data being transmitted from the
test servers to the JMeter 2.4 client to be multiplied by about 10X. The pauses occurred at
regular intervals during the test run - where the test would run fine for about 1 min, and
25 secs, and then 'pause' for about 35 secs, and then continue for another 1 min, 25 secs,
then pause for another 35 secs, with this pattern repeating until the end of the test. One
of the key symptoms of the problem was that the servers involved and the JMeter client all
showed 'idle' (CPU, Network I/O, and Disk I/O) during the 'pause' period - indicating that
they were not 'catching up' on handling requests, but that they had nothing to work on during
the pause. The problem was eventually traced to have 'iptables' enabled on the Apache (HTTPS)
web server that was being hit directly by JMeter. The iptables service is the Linux 'firewall'
application. And while it was not filtering any of the test packets out, it was parsing each
packet - which was substantially slowing its ability to service incoming network traffic.
Eventually, the server would back up on servicing incoming packets to the point that it would
fill its buffers, and stop accepting requests for a specified 'backoff' period (~35 seconds).
Disabling 'iptables' on the Linux hosts resolved the problem completely.
  
+ ==== Test conditions: ====
+ 
-  Client Configuration:
+ ===== Client Configuration: =====
   
   * JMeter 2.4 being run on a Windows XP box
   
@@ -17, +19 @@

   
   * Key Issue - when "Retrieve All Embedded Resources" is enabled, test runs for ~500-600
iterations (2400 of the 4 pages + 10X that in embedded resources), then pauses for about 35
seconds, then starts running at full speed again. (THE PAUSE IS NOT INTENDED, AND IS THE PRECISE
PROBLEM EXPERIENCED.)
   
- <br />
-  Server Configuration:
+ ===== Server Configuration: =====
   
   * Apache Web (HTTPS) Server - configured for AJP Proxy to Tomcat Java App Server
   

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