Unreachable Memory not freed

[yu.zhang at oracle.com]

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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