G1 feedback

[Alex Aisinzon]

Hi all

 

Thoughts on this feedback about G1?

 

Take care

 

Alex A

 

From: Alex Aisinzon 
Sent: Saturday, March 26, 2011 6:46 AM
To: hotspot-gc-use at openjdk.java.net
Subject: G1 feedback

 

Hi all

 

I experimented with G1 and Sun JDK 1.6 update 24 and ran two long
running tests (8 hours) with it:

With " -server -XX:+UseG1GC -XX:+UseCompressedOops -Xms24576m
-Xmx24576m", most pauses were very short. 4 pauses were around 7 seconds
and 4 at 34 seconds.

I then added the objective of keeping the longest pause around 1 second
and used "-server -XX:+UseG1GC -XX:MaxGCPauseMillis=1000
-XX:+UseCompressedOops -Xms24576m -Xmx24576m". Most pauses were a little
above 1 second except for one pause at 8 seconds and one at 57 seconds.

The server is a dual X5570 (8 cores total) and has 48GB of RAM. Its
average CPU utilization was around 60-65% so it was not over-used.

Everything would be perfect if it were not for the 7, 34 and 8, 57
seconds pauses.

What would you recommend I do to either reduce these longer pauses or
give insights into what happened so that G1 can avoid these very rare
but pretty long pauses in the future?

 

Thanks in advance

 

Alex A

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