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<p class=MsoNormal>Hello,<o:p></o:p></p>
<p class=MsoNormal><o:p> </o:p></p>
<p class=MsoNormal>I have a few validation questions based on the following G1
GC log excerpt.<o:p></o:p></p>
<p class=MsoNormal><o:p> </o:p></p>
<p class=MsoNormal>19.298: [GC pause (young) (initial-mark)
2141M->1957M(4000M)20.433: [GC concurrent-mark-start]<o:p></o:p></p>
<p class=MsoNormal>, 1.1346080 secs]<o:p></o:p></p>
<p class=MsoNormal>20.721: [GC pause (young)20.761: [GC concurrent-mark-end,
0.2501590 sec]<o:p></o:p></p>
<p class=MsoNormal> 2300M->2119M(4000M), 1.3597880 secs]<o:p></o:p></p>
<p class=MsoNormal>22.081: [GC remark, 0.0012060 secs]<o:p></o:p></p>
<p class=MsoNormal>22.083: [GC concurrent-count-start]<o:p></o:p></p>
<p class=MsoNormal>22.452: [GC pause (young) 2469M->2119M(4000M), 0.3101740
secs]<o:p></o:p></p>
<p class=MsoNormal>22.976: [GC concurrent-count-end, 0.8934030]<o:p></o:p></p>
<p class=MsoNormal>23.063: [GC cleanup 2435M->639M(4000M), 0.0142190 secs]<o:p></o:p></p>
<p class=MsoNormal>23.078: [GC concurrent-cleanup-start]<o:p></o:p></p>
<p class=MsoNormal>23.086: [GC concurrent-cleanup-end, 0.0083300]<o:p></o:p></p>
<p class=MsoNormal>23.108: [GC pause (young) 660M->338M(4000M), 0.2031580
secs]<o:p></o:p></p>
<p class=MsoNormal>23.632: [GC pause (partial) 668M->346M(4000M), 0.3303010
secs]<o:p></o:p></p>
<p class=MsoNormal><o:p> </o:p></p>
<p class=MsoNormal><o:p> </o:p></p>
<p class=MsoNormal>From what I read in concurrentMarkThread.cpp and
g1CollectorPolicy.cpp in the current OpenJDK 7 G1 source code, could I please
get the following confirmed or denied to ensure my understanding is correct?<o:p></o:p></p>
<p class=MsoNormal><o:p> </o:p></p>
<p class=MsoNormal>The “GC pause” lines are indeed stop-the-world
pauses as blatantly marked. <span style='font-family:Wingdings'>J</span><o:p></o:p></p>
<p class=MsoNormal><o:p> </o:p></p>
<p class=MsoNormal>The “GC pause (young)” lines are only evacuating
young gen regions.<o:p></o:p></p>
<p class=MsoNormal><o:p> </o:p></p>
<p class=MsoNormal>The “GC pause (young) (initial-mark)” line is
both evacuating young gen regions and prepping for a full collection with
initial marking of roots.<o:p></o:p></p>
<p class=MsoNormal><o:p> </o:p></p>
<p class=MsoNormal>The “remark” line is also a stop-the-world pause,
i.e. the G1 “Final Marking Pause” noted in the G1 whitepaper.<o:p></o:p></p>
<p class=MsoNormal><o:p> </o:p></p>
<p class=MsoNormal>The “cleanup” line is also a stop-the-world
pause and finalizes the live object counts and sizes. The heap allocated
size should be the ending size reported on the “cleanup” line plus
any allocations and/or GC activity that occur during the concurrent cleanup
phase.<o:p></o:p></p>
<p class=MsoNormal><o:p> </o:p></p>
<p class=MsoNormal>All “concurrent” lines run concurrently with
application threads, similar to the CMS behavior, and in a set of one or more ConcurrentMarkThread
instances.<o:p></o:p></p>
<p class=MsoNormal><o:p> </o:p></p>
<p class=MsoNormal><o:p> </o:p></p>
<p class=MsoNormal>Thank you for your help,<o:p></o:p></p>
<p class=MsoNormal><o:p> </o:p></p>
<p class=MsoNormal>Ryan<o:p></o:p></p>
<p class=MsoNormal><o:p> </o:p></p>
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