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Bug ID: JDK-7178361 G1: Make sure that PrintGC and PrintGCDetails use the same timing for the GC pause
JDK-7178361 : G1: Make sure that PrintGC and PrintGCDetails use the same timing for the GC pause

Details
Type:
Bug
Submit Date:
2012-06-20
Status:
Resolved
Updated Date:
2013-04-30
Project Name:
JDK
Resolved Date:
2012-07-24
Component:
hotspot
OS:
generic
Sub-Component:
gc
CPU:
generic
Priority:
P3
Resolution:
Fixed
Affected Versions:
hs24
Fixed Versions:
hs24 (b17)

Related Reports
Backport:
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Sub Tasks

Description
-XX:+PrintGC and -XX:+PrintGCDetails use different timers to track the G1 collection pauses.

It turns out that the timing used by -XX:+PrintGCDetails only covers part of the pause.

Running SPECjbb2005 I got GC pause logging like this:

PrintGCDetails:           13 ms
PrtinGC:                  57 ms
PrintSafepointStatistics: 61 ms 

The PrintSafepointStatistics is as close to the actual pause as we can get. PrintGC does not cover the whole pause but is fairly close. PrintGCDetails is missing a large part of the pause.

To analyze G1 performance we normally run with PrintGCDetails, so it is important that this information is correct.

                                    

Comments
EVALUATION

http://hg.openjdk.java.net/hsx/hotspot-gc/hotspot/rev/922993931b3d
                                     
2012-07-12
EVALUATION

http://hg.openjdk.java.net/hsx/hotspot-emb/hotspot/rev/922993931b3d
                                     
2012-07-24



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