From: Erik Groeneveld <erik@cq2.nl>
To: Andrew Haley <aph@redhat.com>
Cc: java@gcc.gnu.org
Subject: Re: GC leaks debugging
Date: Fri, 01 Apr 2011 09:03:00 -0000 [thread overview]
Message-ID: <AANLkTikG2CBU8q2yde+NZLJ8x7Rcg2jHQG0Ojmc0g=ks@mail.gmail.com> (raw)
In-Reply-To: <4D95909E.4060309@redhat.com>
On Fri, Apr 1, 2011 at 10:45, Andrew Haley <aph@redhat.com> wrote:
> On 01/04/11 09:39, Erik Groeneveld wrote:
>> L.S.,
>>
>> I am debugging memory leaks in the GC of libgcj. Generally, libgcj
>> performs well, but there are some cases in which the heap literally
>> explodes over time. I wish to solve this. The OpenJDK vm runs the same
>> tests without any leaking.
>>
>> I compiled GCC 4.6, build with --enable-libgcj-debug=yes and started
>> testing with GC_DUMP_REGULARLY=1. From the results I have a few
>> questions to understand it better. I am still in a phase of
>> pinpointing a minimal program to demonstrate the problem, and I would
>> like to get hints as to search further.
>>
>> 1. The finalization table entries keeps on increasing up to 39344
>> until it is killed, but the objects which are eligible for immediate
>> finalization remains 0. It seems that no finalization takes place.
>> Could you give any hints as to what could be the reason for this? It
>> logs:
>>
>> ***Finalization statistics:
>> 39344 finalization table entries; 48 disappearing links
>> 0 objects are eligible for immediate finalization
>>
>> ***Static roots:
>> From 0x804b284 to 0x804bf1c (temporary)
>> From 0xb716d000 to 0xb7854cdc (temporary)
>> From 0xb55ba92c to 0xb562ddbc (temporary)
>> Total size: 7716356
>>
>>
>> 2. There is a fair amount of black-listing. From reading about the
>> GC, I understand that the GC knows what is a pointer and what not
>> because there is type information associated with the Java objects.
>> So I'd expect no black-listing at all. It that a right observation?
>
> No. Objects are scanned precisely, but the stack is not.
Thanks. I think I can rule the stack out by reviewing/adapting my
test program. I'll do that first.
> Also, depending
> on your compilation options, the data segments of your program may be
> scanned conservatively.
I have to think about this one. Which options are you thinking of?
Erik
next prev parent reply other threads:[~2011-04-01 9:03 UTC|newest]
Thread overview: 42+ messages / expand[flat|nested] mbox.gz Atom feed top
2011-04-01 8:39 Erik Groeneveld
2011-04-01 8:45 ` Andrew Haley
2011-04-01 9:03 ` Erik Groeneveld [this message]
2011-04-01 9:34 ` Andrew Haley
2011-04-02 0:27 ` Boehm, Hans
2011-04-02 9:39 ` Erik Groeneveld
2011-04-03 17:15 ` Erik Groeneveld
2011-04-03 18:00 ` Erik Groeneveld
2011-04-04 8:13 ` Andrew Haley
2011-04-04 8:53 ` Erik Groeneveld
2011-04-04 9:48 ` Andrew Haley
2011-04-05 4:44 ` Boehm, Hans
2011-04-05 8:58 ` Andrew Haley
2011-04-05 6:50 ` Erik Groeneveld
2011-04-05 9:02 ` Andrew Haley
2011-04-05 12:02 ` Erik Groeneveld
2011-04-05 12:55 ` Andrew Haley
2011-04-06 14:30 ` Erik Groeneveld
2011-04-06 18:33 ` Andrew Haley
2011-04-06 18:39 ` David Daney
2011-04-07 17:43 ` Erik Groeneveld
2011-04-08 8:12 ` Erik Groeneveld
2011-04-08 13:56 ` Andrew Haley
2011-04-08 15:35 ` David Daney
2011-04-08 15:53 ` Erik Groeneveld
2011-04-08 15:57 ` Andrew Haley
2011-04-08 15:48 ` Erik Groeneveld
2011-04-09 1:17 ` Boehm, Hans
2011-04-09 8:47 ` Andrew Haley
2011-04-09 10:56 ` Erik Groeneveld
2011-04-10 11:03 ` Erik Groeneveld
2011-04-12 18:43 ` Erik Groeneveld
2011-04-13 8:11 ` Andrew Haley
2011-04-13 12:11 ` Bryce McKinlay
2011-04-13 14:27 ` Andrew Haley
2011-04-14 8:36 ` Erik Groeneveld
2011-04-14 8:43 ` Andrew Haley
2011-04-14 10:02 ` Erik Groeneveld
2011-04-14 10:50 ` Andrew Haley
2011-04-15 7:32 ` Erik J Groeneveld
2011-04-01 17:41 ` David Daney
2011-04-02 16:21 ` Erik Groeneveld
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