On 06/28/2012 06:13 PM, Eric Luong wrote:
> OK, I will check it out while in the different states. However, I am
> not sure there is actually a leak. What I'm seeing is that memory
> usage seems to plateau after a certain number of clients, rather than
> continuing to increase linearly. I'm trying to understand why this
> happens.
Just to make sure, all those clients (2000+) are active (in the
long-polling state) at the same time, right?
WBR,
Alexey.
>
> Thanks,
>
> Eric
>
> On Thu, Jun 28, 2012 at 9:57 AM, Oleksiy Stashok
> <oleksiy.stashok_at_oracle.com <mailto:oleksiy.stashok_at_oracle.com>> wrote:
>
> Hi Eric,
>
> I think you're on the right way.
> See inline...
>
>
> On 06/28/2012 04:40 AM, Eric Luong wrote:
>> Any suggestions on what to look for with jmap/jhat? I'm
>> unfamiliar with the tools. When I run jhat on a heap dump, it
>> comes up with a fair number of warnings -- "Failed to resolve
>> object id [some id]" and "Failed to resolve object id [some id]
>> for field value (signature L)". Not sure what these mean. It
>> might be worth mentioning that I had to use -F on jmap; without
>> it, I get the "target process is not responding".
> That's correct.
>
>
>>
>> Just looking at this snapshot (which is not near the plateau I
>> described), it seems the class with the largest total size is
>> "class [C" which is obviously not a useful class name.
> It's character arrays.
> I just took snapshot w/ jmap and opened in jhat.
> In the browser I clicked "Heap histogram", now I see types sorted
> by number of instances and memory consumption.
>
> When you investigate the problem, pls. take a snapshot when issue
> occurs and check the heap histogram. Most probably the problematic
> object (which leaks) would be on the top of the list.
>
>
>
>> Does that mean it is some anonymous class? Exploring it further,
>> it only lists Object as its superclass. There are several other
>> such nameless classes. Other information for these classes
>> (ClassLoader, Signers, Protection Domain) are all null. Other
>> classes that seem to consume the majority of memory are HashMap,
>> HashMapEntry and related classes.
> Most of the time char[] is at the top of the list, different
> collections like HashMap also.
> Pls. take a snapshot when the memory issue occurs and check the
> heap histogram, may be you'll find some suspicious object on the
> top. If not - you can share the snapshot file, I can try to help.
>
>
>>
>> Can you suggest how to approach this using jmap/jhat, and if
>> those warnings I received are of any significance?
> I also see warnings from jhat, but IMO it's still ok.
>
> You can also check another profiler tools like the one Chris
> suggested (visual vm).
>
> Thanks.
>
> WBR,
> Alexey.
>
>
>> Then I will proceed with checking out different memory state
>> snapshots.
>>
>> Thanks for your help,
>>
>> Eric
>>
>> On Mon, Jun 25, 2012 at 6:37 AM, Oleksiy Stashok
>> <oleksiy.stashok_at_oracle.com <mailto:oleksiy.stashok_at_oracle.com>>
>> wrote:
>>
>> Hi Eric,
>>
>> it would be great if you can monitor the memory usage using
>> some profiler tool or jmap/jhat and give us more details on
>> objects (object types), which consume memory. You can take
>> several memory state snapshots like initial, 1000 clients
>> connected, 2000 clients connected, 3000 clients connected, so
>> we can see the dynamics and figure out the problem (if there
>> is any).
>>
>> Thanks.
>>
>> WBR,
>> Alexey.
>>
>>
>> On 06/23/2012 04:48 AM, Eric Luong wrote:
>>
>> Hello,
>>
>> I've been testing Grizzly in Glassfish 3.1 by simulating
>> a load of thousands of clients using long polling. I
>> found what appears to be a bottleneck. As more clients
>> are added, the memory usage of the server increases.
>> However, after a certain point (2000 clients in my case,
>> but I expect it would depend on hardware) the usage seems
>> to taper off and plateau.
>>
>> I have been trying to figure out why the memory usage
>> plateaus. Can anyone offer some insights, or suggest a
>> way to investigate further?
>>
>> Thank-you!
>>
>> Eric
>>
>>
>>
>>
>
>
>