RFR: JDK-8087291: InitialBootClassLoaderMetaspaceSize and CompressedClassSpaceSize should be checked consistent from MaxMetaspaceSize
Yasumasa Suenaga
yasuenag at gmail.com
Wed Sep 27 03:05:35 UTC 2017
Hi all,
I added a testcase for this issue in new webrev:
http://cr.openjdk.java.net/~ysuenaga/JDK-8087291/webrev.04/
Thanks,
Yasumasa
2017-09-26 18:36 GMT+09:00 Yasumasa Suenaga <yasuenag at gmail.com>:
> Hi all,
>
> I uploaded webrev for this issue against jdk10/hs.
> Could you review it?
>
> http://cr.openjdk.java.net/~ysuenaga/JDK-8087291/webrev.03/
>
>
> I cannot access JPRT. So I need a sponsor.
>
>
> Thanks,
>
> Yasumasa
>
>
>
> 2017-09-21 3:11 GMT+09:00 Man Cao <manc at google.com>:
>> Thank Yasumasa and Stefan for the responses.
>>
>> Good to know that the patch is not blocked due to breaking some internal
>> invariants/assumptions, but just due to its P5 status.
>> Is it possible to push it to P4?
>>
>> -Man
>>
>> On Wed, Sep 20, 2017 at 5:16 AM, Yasumasa Suenaga <yasuenag at gmail.com>
>> wrote:
>>>
>>> Hi,
>>>
>>> (CC'ed hotspot-runtime-dev)
>>>
>>>> I think the reason is that this bug is a P5. The compressed class space
>>>> belongs to the runtime code, so you might get more traction for this on the
>>>> hotspot-runtime-dev list.
>>>
>>>
>>> I will send review request against jdk10/master or jdk10/hs after repos
>>> are opened.
>>>
>>>
>>> Thanks,
>>>
>>> Yasumasa
>>>
>>>
>>>
>>> On 2017/09/20 20:53, Stefan Karlsson wrote:
>>>>
>>>> Hi Man,
>>>>
>>>> On 2017-09-13 20:55, Man Cao wrote:
>>>>>
>>>>> Hi Yasumasa, Stefan,
>>>>>
>>>>> Do you have any thoughts on why this patch has been pending for 2+
>>>>> years? This patch could really save us from some annoying issues since we
>>>>> are automatically monitoring hsperfdata counters.
>>>>
>>>>
>>>> I think the reason is that this bug is a P5. The compressed class space
>>>> belongs to the runtime code, so you might get more traction for this on the
>>>> hotspot-runtime-dev list.
>>>>
>>>> StefanK
>>>>
>>>>>
>>>>> -Man
>>>>>
>>>>> On Mon, Aug 21, 2017 at 3:46 PM, Man Cao <manc at google.com
>>>>> <mailto:manc at google.com>> wrote:
>>>>>
>>>>> Hi all,
>>>>>
>>>>> I wonder if there is any recent update on the patch for JDK-8087291.
>>>>> Is it possible to push this patch into JDK9? Except for its low
>>>>> priority (P5),
>>>>> is there any complication that prevents this patch getting approved
>>>>> (for example, some JVM logic requires CompressedClassSpaceSize to be
>>>>> 1GB by default)?
>>>>>
>>>>> I work in the Java Platform Team at Google. We have encountered
>>>>> annoying issues that the hsperfdata counter
>>>>> "sun_gc_metaspace_maxCapacity" reporting
>>>>> a too large value (about 1GB) even if user sets
>>>>> -XX:MaxMetaspaceSize=100m, as well as GC log shows the confusing 1GB
>>>>> memory reserved by metaspace,
>>>>> regardless of MaxMetaspaceSize value. The root cause for these
>>>>> issues is that CompressedClassSpaceSize is not automatically capped
>>>>> by MaxMetaspaceSize
>>>>> during VM initialization, and this patch seems fix the root cause.
>>>>> (I'm aware that even after this patch, the reserved size could still
>>>>> be up to 2*MaxMetaspaceSize,
>>>>> but it is better than the current situation.)
>>>>>
>>>>> Thanks,
>>>>> Man
>>>>>
>>>>> On 6/19/2015 00:34, Yasumasa Suenaga wrote:
>>>>>
>>>>> Thank you for your comment!
>>>>> > Try running a debug JVM with your patch with this command
>>>>> line.
>>>>> >
>>>>> > java -XX:MaxMetaspaceSize=4195328 -version
>>>>> Sorry, I've fixed it and uploaded webrev:
>>>>> http://cr.openjdk.java.net/~ysuenaga/JDK-8087291/webrev.02/
>>>>> <http://cr.openjdk.java.net/~ysuenaga/JDK-8087291/webrev.02/>
>>>>> It works on fastdebug VM.
>>>>> Please review again.
>>>>>
>>>>> Thanks,
>>>>> Yasumasa
>>>>>
>>>>> On 2015/06/18 10:45, Jon Masamitsu wrote:
>>>>> > Yasumasa,
>>>>> >
>>>>> > Try running a debug JVM with your patch with this command
>>>>> line.
>>>>> >
>>>>> > java -XX:MaxMetaspaceSize=4195328 -version
>>>>> >
>>>>> > On a linux system I get this when I build with your patch.
>>>>> >
>>>>> >> java -XX:MaxMetaspaceSize=4195328 -version
>>>>> >> # To suppress the following error report, specify this
>>>>> argument
>>>>> >> # after -XX: or in .hotspotrc:
>>>>> SuppressErrorAt=/metaspace.cpp:2324
>>>>> >> #
>>>>> >> # A fatal error has been detected by the Java Runtime
>>>>> Environment:
>>>>> >> #
>>>>> >> # Internal Error
>>>>> >>
>>>>>
>>>>> (/export/jmasa/java/jdk9-gc-code_review/src/share/vm/memory/metaspace.cpp:2324),
>>>>> >> pid=19099, tid=0x00007ff4b9b92700
>>>>> >> # assert(size > MediumChunk || size > ClassMediumChunk)
>>>>> failed: Not a
>>>>> >> humongous chunk
>>>>> >> #
>>>>> >
>>>>> >
>>>>> > Jon
>>>>> >
>>>>> >
>>>>> > On 6/17/2015 7:54 AM, Yasumasa Suenaga wrote:
>>>>> >> I want to continue to discuss about CompressedClassSpace and
>>>>> MaxMetaspace in this (RFR) thread.
>>>>> >>
>>>>> >>
>>>>>
>>>>> http://mail.openjdk.java.net/pipermail/hotspot-gc-dev/2015-June/013873.html
>>>>>
>>>>> <http://mail.openjdk.java.net/pipermail/hotspot-gc-dev/2015-June/013873.html>
>>>>> >>>> Should I resize CompressedClassSpaceSize than to show
>>>>> error message?
>>>>> >>> If you add slightly better heuristics for the setup of the
>>>>> CompressedClassSpaceSize flag, for example lowering the
>>>>> CompressedClassSpaceSize when MaxMetaspaceSize is set, then it
>>>>> might be less likely that you'll hit the OutOfMemoryError when
>>>>> the system is set up with strict overcommit settings.
>>>>> >>
>>>>> >> I've uploaded new webrev:
>>>>> >> http://cr.openjdk.java.net/~ysuenaga/JDK-8087291/webrev.01/
>>>>> <http://cr.openjdk.java.net/~ysuenaga/JDK-8087291/webrev.01/>
>>>>> >>
>>>>> >> This patch checkes MaxMetaspaceSize,
>>>>> CompressedClassSpaceSize, and
>>>>> >> InitialBootClassLoaderMetaspaceSize.
>>>>> >>
>>>>> >> I add to check CompressedClassSpaceSize in
>>>>> Arguments::set_use_compressed_klass_ptrs().
>>>>> >> If InitialBootClassLoaderMetaspaceSize is greater than
>>>>> MaxMetaspaceSize,
>>>>> >> VM will fail with error message.
>>>>> >>
>>>>> >> InitialBootClassLoaderMetaspaceSize will be set to
>>>>> MaxMetaspaceSize
>>>>> >> when UseCompressedClassPointers is not set in
>>>>> Metaspace::ergo_initialize().
>>>>> >>
>>>>> >>
>>>>> >> Thanks,
>>>>> >>
>>>>> >> Yasumasa
>>>>> >>
>>>>>
>>>>>
>>
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