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Posted to jmeter-dev@jakarta.apache.org by bu...@apache.org on 2007/10/30 07:29:00 UTC

DO NOT REPLY [Bug 43730] New: - User-settable JVM DNS cache expiry

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http://issues.apache.org/bugzilla/show_bug.cgi?id=43730

           Summary: User-settable JVM DNS cache expiry
           Product: JMeter
           Version: unspecified
          Platform: Other
        OS/Version: other
            Status: NEW
          Severity: normal
          Priority: P2
         Component: Main
        AssignedTo: jmeter-dev@jakarta.apache.org
        ReportedBy: sonam.chauhan@ce.com.au


I understand that the JVM caches successfull DNS name lookups forever by 
default. This is confirmed by this document (see note on 
networkaddress.cache.ttl property):
  http://java.sun.com/j2se/1.4.2/docs/guide/net/properties.html

The Java DNS cache ignores the DNS TTL property. This can cause issues, for 
instance with a long-running test when an IP address changes on a server farm, 
or when DNS round-robin load balancing is used during a load test (a JMeter 
instance will only ever test one node in a cluster). 

Can JMeter be enhanced to allow the user to override Java's default DNS-
caching behaviour in a user-setting at the beginning of the test?  This will 
enable it to work properly (i.e. as a browser would) in these scenarios. The 
setting would allow the user to set a time limit on networkaddress.cache.ttl  -
it could be set to emulate IE (30 minutes, according to some reports) or 
Firefox (1 minute). 

This issue was discussed on the JMeter users list towards end-October 2007:
http://mail-archives.apache.org/mod_mbox/jakarta-jmeter-user/200710.mbox/%
3cE5D178BFB0356B48A48B8330B2903721035E76B2@syd1exc04.CE.CORP%3e

This could be implemented as part of a more generic control to set the Java 
Network properties (see the first link above.)

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DO NOT REPLY [Bug 43730] - User-settable JVM DNS cache expiry

Posted by bu...@apache.org.
DO NOT REPLY TO THIS EMAIL, BUT PLEASE POST YOUR BUG�
RELATED COMMENTS THROUGH THE WEB INTERFACE AVAILABLE AT
<http://issues.apache.org/bugzilla/show_bug.cgi?id=43730>.
ANY REPLY MADE TO THIS MESSAGE WILL NOT BE COLLECTED AND�
INSERTED IN THE BUG DATABASE.

http://issues.apache.org/bugzilla/show_bug.cgi?id=43730


sebb@apache.org changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
           Severity|normal                      |enhancement




------- Additional Comments From sebb@apache.org  2007-10-30 05:13 -------
As a work-round for Sun JVMs, the property sun.net.inetaddr.ttl can be set on 
the command-line using -D or in the JMeter file system.properties.

Other Java networking properties can be set on the command-line or in 
system.properties.

It is only networkaddress.cache.ttl that cannot be set this way; it would need 
to be set by:

java.security.Security.setProperty("networkaddress.cache.ttl" , "0");

This can be done with the current JMeter by using the JMeter property

beanshell.init.file

which names a BeanShell script to be run at startup. Of course this requires 
that the BeanShell jar has been put on the classpath (e.g. in lib/).

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