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

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

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

Dmitry Fazunenko
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 [hidden email]
To: hotspot-gc-dev [hidden email]


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

Igor Ignatyev
Hi Dima,

the fix looks good to me, thank you.

— Igor

> On Jan 9, 2017, at 4:50 PM, Dmitry Fazunenko <[hidden email]> wrote:
>
> 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 <[hidden email]>
> To: hotspot-gc-dev <[hidden email]>
>
> 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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Re: RFR (XXS): 8169643: [TESTBUG] GCBasher test fails with G1, CMS and Serial.

Dmitry Fazunenko
Hi Igor,

thanks for such a prompt response.

-- Dima

On 09.01.2017 16:57, Igor Ignatyev wrote:

> Hi Dima,
>
> the fix looks good to me, thank you.
>
> — Igor
>> On Jan 9, 2017, at 4:50 PM, Dmitry Fazunenko <[hidden email]> wrote:
>>
>> 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 <[hidden email]>
>> To: hotspot-gc-dev <[hidden email]>
>>
>> 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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Re: Fwd: RFR (XXS): 8169643: [TESTBUG] GCBasher test fails with G1, CMS and Serial.

Michail Chernov
In reply to this post by Dmitry Fazunenko

Hi Dima,

The change looks good to me.

Misha


On 09.01.2017 16:50, Dmitry Fazunenko wrote:
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 [hidden email]
To: hotspot-gc-dev [hidden email]


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

Thomas Schatzl
In reply to this post by Dmitry Fazunenko
Hi,

On Mon, 2017-01-09 at 16:50 +0300, Dmitry Fazunenko wrote:

> 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
>

  I think the limitation has been introduced so that gcbasher does
something useful, i.e. execute enough GCs. With a multi-GB heap at its
disposal, I expect that the amount of GCs executed will be
significantly lower than it is now.

I prefer to have a 256M limit to none; and maybe the test could be run
once with and without UseCompressedOops with appropriate heap sizes
instead if there is enough cpu time in our testing infrastructure.

Thanks,
  Thomas

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

Dmitry Fazunenko
Hi Thomas,



On 09.01.2017 17:38, Thomas Schatzl wrote:

> Hi,
>
> On Mon, 2017-01-09 at 16:50 +0300, Dmitry Fazunenko wrote:
>> 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
>>
>    I think the limitation has been introduced so that gcbasher does
> something useful, i.e. execute enough GCs. With a multi-GB heap at its
> disposal, I expect that the amount of GCs executed will be
> significantly lower than it is now.

Your arguments do certainly make sense.
> I prefer to have a 256M limit to none; and maybe the test could be run
> once with and without UseCompressedOops with appropriate heap sizes
> instead if there is enough cpu time in our testing infrastructure.
I suggest to start with original version of the fix:
http://cr.openjdk.java.net/~dfazunen/8169643/webrev.00/
(+ copyright updates)

and submit an RFE to limit max heap size depending of UseCompressedOops
value.
Such RFE could implemented much easily after integration of
     JDK-8172417 Verundy: Library to simplify using TestNG for Hotspot
test development
Now it's a bit tricky to get known from the test the values of external
tags.

Are you okay with that?

Thanks,
Dima

>
> Thanks,
>    Thomas
>

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

Thomas Schatzl
Hi Dima,

On Tue, 2017-01-10 at 19:09 +0300, Dmitry Fazunenko wrote:

> Hi Thomas,
>
>
>
> On 09.01.2017 17:38, Thomas Schatzl wrote:
> >
> > Hi,
> >
> > On Mon, 2017-01-09 at 16:50 +0300, Dmitry Fazunenko wrote:
> > >
> > > 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
> > >
> >    I think the limitation has been introduced so that gcbasher does
> > something useful, i.e. execute enough GCs. With a multi-GB heap at
> > its
> > disposal, I expect that the amount of GCs executed will be
> > significantly lower than it is now.
> Your arguments do certainly make sense.
> >
> > I prefer to have a 256M limit to none; and maybe the test could be
> > run
> > once with and without UseCompressedOops with appropriate heap sizes
> > instead if there is enough cpu time in our testing infrastructure.
> I suggest to start with original version of the fix:
> http://cr.openjdk.java.net/~dfazunen/8169643/webrev.00/
> (+ copyright updates)
>
> and submit an RFE to limit max heap size depending of
> UseCompressedOops 
> value.
> Such RFE could implemented much easily after integration of
>      JDK-8172417 Verundy: Library to simplify using TestNG for
> Hotspot  test development
> Now it's a bit tricky to get known from the test the values of
> external tags.
>
> Are you okay with that?

 yes, thanks.

Thomas

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

Dmitry Fazunenko
For the record, the final version of change:
http://cr.openjdk.java.net/~dfazunen/8169643/webrev.03/


Thanks
Dima
PS: JDK-8172556 was submitted for the further improvement.


On 10.01.2017 22:58, Thomas Schatzl wrote:
Hi Dima,

On Tue, 2017-01-10 at 19:09 +0300, Dmitry Fazunenko wrote:
Hi Thomas,



On 09.01.2017 17:38, Thomas Schatzl wrote:
Hi,

On Mon, 2017-01-09 at 16:50 +0300, Dmitry Fazunenko wrote:
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

   I think the limitation has been introduced so that gcbasher does
something useful, i.e. execute enough GCs. With a multi-GB heap at
its
disposal, I expect that the amount of GCs executed will be
significantly lower than it is now.
Your arguments do certainly make sense.
I prefer to have a 256M limit to none; and maybe the test could be
run
once with and without UseCompressedOops with appropriate heap sizes
instead if there is enough cpu time in our testing infrastructure.
I suggest to start with original version of the fix:
http://cr.openjdk.java.net/~dfazunen/8169643/webrev.00/
(+ copyright updates)

and submit an RFE to limit max heap size depending of
UseCompressedOops 
value.
Such RFE could implemented much easily after integration of
     JDK-8172417 Verundy: Library to simplify using TestNG for
Hotspot  test development
Now it's a bit tricky to get known from the test the values of
external tags.

Are you okay with that?
 yes, thanks.

Thomas