Fwd: RFR (XXS): 8169643: [TESTBUG] GCBasher test fails with G1, CMS and Serial.

Dmitry Fazunenko dmitry.fazunenko at oracle.com
Mon Jan 9 13:50:44 UTC 2017


Hi in the new year!

I got off line comment from Igor I. that  Xmx is not needed here at all.
And I agree with Igor.
GCBasher test was written many years ago, probably in those times when 
default maximum heap size was 64MB.
So, specifying Xmx was necessary to increase heap to allocate such a big 
structure.
Nowadays, it's hard to find a host where maximum heap size set by the 
ergonomics will be less than 256MB.
GCBasher doesn't try to allocate all available memory, it just allocates 
a big structure several time.
So, I think -Xmx option could be removed from this test:

http://cr.openjdk.java.net/~dfazunen/8169643/webrev.02/

Tested by RBT with and without -XX:-UseCompressedOpps


Thanks,
Dima



-------- Forwarded Message --------
Subject: 	RFR (XXS): 8169643: [TESTBUG] GCBasher test fails with G1, CMS 
and Serial.
Date: 	Thu, 29 Dec 2016 17:25:26 +0300
From: 	Dmitry Fazunenenko <dmitry.fazunenko at oracle.com>
To: 	hotspot-gc-dev <hotspot-gc-dev at openjdk.java.net>



Hi everyone,

I'm looking for a couple of review for a simple change in test: -Xmx128m
-> -Xmx256m

http://cr.openjdk.java.net/~dfazunen/8169643/webrev.00/
https://bugs.openjdk.java.net/browse/JDK-8169643

The GCBasher test fails with OOM if run with -XX:-UseCompressedOpps.
The root cause is 128Mb is not enough to locate a big structure if Opps
are not compressed.
Giving more memory fixes the problem (TestGCBasherWithParallel.java
specifies 256m and doesn't fail)

Thanks,
Dima


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