Unreachable Memory not freed

[yu.zhang at oracle.com]

Thorsten,

I have updated the bug with more details. I think there is some 
inaccuracy when reporting the heap dump.

There might be some memory leak in your application as well.

Thanks

Jenny

On 01/27/2017 04:50 PM, Jenny Zhang wrote:
> Hi, Thorsten,
>
> I can reproduce this with a micro. I have filed 
> https://bugs.openjdk.java.net/browse/JDK-8173594
>
> The micro is mostly based on 
> http://stackoverflow.com/questions/26027313/how-to-load-and-parse-svg-documents 
> with some modification. I will upload the micro and details later.
>
> I think this is a issue how jvmti and gc reporting unreachable 
> objects. Those objects should not be reported as unreachable.
>
> Thanks
> Jenny
>
> On 1/25/2017 3:23 PM, yu.zhang at oracle.com wrote:
>> Thorsten,
>>
>> Thanks very much for the heap dump and gc log.
>>
>> I assume the gc log and heap dump are from the same run. It is very 
>> interesting, in the gc log:
>>
>> 2017-01-24T16:41:17.184-0100: 1301.633: [Full GC (Heap Dump Initiated 
>> GC)  3817M->3816M(4096M), 8.9543444 secs]
>>    [Eden: 2048.0K(2048.0M)->0.0B(2048.0M) Survivors: 0.0B->0.0B Heap: 
>> 3817.7M(4096.0M)->3816.2M(4096.0M)], [Metaspace: 
>> 142921K->142921K(1175552K)]
>>  [Times: user=16.35 sys=0.11, real=8.95 secs]
>>
>> GC thinks there are 3816.2M of objects alive. But in the heap dump, 
>> there is only 1.8G alive.
>>
>> I can see those unreachable objects with yourkit, mostly are
>>
>> org.apache.batik.dom.GenerecText
>>
>> But apparently gc does not think those are dead. It could be a bug in 
>> gc, or jvmti dumping the heap, or tool(yourkit, apache MAT). I need 
>> to discuss this with dev team.
>>
>> Back to the gc log, it seems the application allocates a lot of 
>> humongous objects. I can see some int[] of 1.5m. In general the heap 
>> is very full, with a lot of to-space exhausted, and full gc. And the 
>> heap usage after full gc is almost the whole heap (4096M).
>>
>> Thanks
>>
>> Jenny
>>
>>
>> On 01/25/2017 01:15 AM, Thorsten Goetzke wrote:
>>> Hello,
>>>
>>> You can find the heap dump and gc logs under 
>>> https://filesender.freigmbh.de/filesender/?vid=10f1aeb6-82b4-3d09-c201-00002042c681
>>>
>>> Link is valid until 28.01.2017 (1/28/2017). Feel free to message me 
>>> if you need a reupload.
>>>
>>> Best Regards,
>>> Thorsten
>>>
>>>
>>>> Thorsten,
>>>>
>>>> Can you please put the heap dump and gc logs somewhere for download?
>>>>
>>>> Thanks
>>>> Jenny
>>>>
>>>> On 1/24/2017 8:30 AM, Thorsten Goetzke wrote:
>>>>> Hello,
>>>>>
>>>>> I am working on a closed source software that uses a patched version
>>>>> of apache-batik to display SVG-Documents one by one. If you keep
>>>>> loading and discarding some specific SVG-Documents memory consumption
>>>>> keeps on growing until it reaches more than 95% of the available
>>>>> memory. The application becomes unusable slow, very little memory 
>>>>> gets
>>>>> freed, although the gc is constantly running. Sometimes an
>>>>> OutOfMemoryError gets thrown. I took memory snaphsots and analyzed
>>>>> them using jvisualvm and yourkit. These tools report the majority of
>>>>> the memory as unreachable.
>>>>> I have tried different garbage collectors (G1,ConcurrentMarkSweep),
>>>>> and different Versions of Java: 1.8_60;1.8_65;1.8_102, the issue is
>>>>> always reproducible.
>>>>> Is there something i can do to debug this further? I am currently not
>>>>> able to reproduce this issue in a somewhat small self contained 
>>>>> example.
>>>>> I could provide gc-logs and the heap dump (about 1gb zipped) or any
>>>>> other debuging info if someone is interested.
>>>>>
>>>>> Best Regards,
>>>>> Thorsten Goetzke
>>>>>
>>>
>>> _______________________________________________
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>>
>
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