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Hi Andreas,<br>
<br>
On 5/21/14 2:05 PM, Andreas Eriksson wrote:<br>
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<blockquote cite="mid:537C9695.5010902@oracle.com" type="cite">A new
webrev is up:
<br>
<a class="moz-txt-link-freetext" href="http://cr.openjdk.java.net/~aeriksso/8038925/webrev.02/">http://cr.openjdk.java.net/~aeriksso/8038925/webrev.02/</a>
<br>
<br>
The test now verifies that no full GC has been done after doing
the heap dump.
<br>
I also modified the test to not run if it for some reason is not
using G1.
<br>
</blockquote>
<br>
Thanks for the update, Andreas.<br>
<br>
The test looks good except for the @run tag.<br>
<br>
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@run main/othervm -Xms512m -Xmx1024m -XX:+UseG1GC
-XX:+ExplicitGCInvokesConcurrent TestG1ConcurrentGCHeapDump<br>
<br>
The problem is that more GC flags will be added when the test is run
in nightly testing. Some GC flags will conflict with UseG1GC. On the
other hand at some point UseG1GC will be one of the flags that is
added.<br>
<br>
So, I think what you need to do is just remove "-XX:+UseG1GC" from
the @run tag. Then your test will report log "skipped" when it is
run in the nightly testing except for the nightly testing done with
G1 where it will actually do something.<br>
<br>
Bengt<br>
<br>
<blockquote cite="mid:537C9695.5010902@oracle.com" type="cite">
<br>
Regards,
<br>
Andreas
<br>
<br>
On 2014-05-21 12:31, Bengt Rutisson wrote:
<br>
<blockquote type="cite">On 5/21/14 12:12 PM, Andreas Eriksson
wrote:
<br>
<blockquote type="cite">Hi Bengt, thanks for looking at this.
<br>
<br>
I agree that verifying that no full GC has happened would be
good.
<br>
One thing I see as problematic though, is what to do if a full
GC has happened.
<br>
Should I make the test fail? Or is there some way to signal
that the test was inconclusive / couldn't finish?
<br>
</blockquote>
<br>
Personally I would prefer to make the test fail. JTreg only has
two states, PASS or FAIL, and I think that if we allow it to
pass we might not notice if there is some change that makes the
test always get a full GC and then never actually testing
anything.
<br>
<br>
I don't think it will fail intermittently by getting full GCs. I
think the test is pretty stable. But I think it would be good to
have a way of noticing if it stops testing what it is supposed
to test.
<br>
<br>
(By the way, I would really like a "SKIPPED" state in JTreg but
I haven't had any luck pushing for that. I think it could be
useful for other things as well. There is for example no good
reason for your test to be run 4 times each night with the exact
same binary. But that is what happens since we can't say that we
should skip this test if we run with any other GC than G1.)
<br>
<br>
Thanks,
<br>
Bengt
<br>
<br>
<blockquote type="cite">
<br>
Regards,
<br>
Andreas
<br>
<br>
On 2014-05-21 11:55, Bengt Rutisson wrote:
<br>
<blockquote type="cite">
<br>
Hi Andreas,
<br>
<br>
The fix looks good.
<br>
<br>
One comment about the test. It does not verify that no full
GC happens. The way the test is set up I guess that should
not happen and I am not sure it is worth the effort to add a
check for it. Just wanted to mention it if you want to make
test more resilient to future changes in the JVM that for
some reason can trigger a full GC for this test.
<br>
<br>
I'm fine with leaving the test as it is.
<br>
<br>
Thanks,
<br>
Bengt
<br>
<br>
<br>
On 5/20/14 4:26 PM, Andreas Eriksson wrote:
<br>
<blockquote type="cite">Hi,
<br>
<br>
Could I have a review for this G1 jdk7 only fix please?
<br>
(There is a related problem in jdk8 and jdk9, where an
assert can fail because of this problem. I have logged
another bug for this.)
<br>
<br>
Description:
<br>
Due to the marking cleanup reclaiming empty regions, and
having stale references a crash can occur when doing a
heap dump.
<br>
The code tries to do an is_klass check on the object,
which crashes the VM.
<br>
The fix is to add an is_perm check before doing the check,
since is_perm will do a bounds check on the oop and if
it's in the perm gen we know it's safe to look at it since
G1 only ever does full compactions of the perm gen.
<br>
<br>
For more information, and a more in-depth analysis, please
see the jira bug.
<br>
<br>
<a class="moz-txt-link-freetext" href="http://cr.openjdk.java.net/~aeriksso/8038925/webrev.01/">http://cr.openjdk.java.net/~aeriksso/8038925/webrev.01/</a>
<br>
<a class="moz-txt-link-freetext" href="https://bugs.openjdk.java.net/browse/JDK-8038925">https://bugs.openjdk.java.net/browse/JDK-8038925</a>
<br>
<br>
Regards,
<br>
Andreas
<br>
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