[Gc] Log Analysis of GC

Boehm, Hans hans.boehm at hp.com
Wed Oct 10 18:35:53 PDT 2012


There was some mailing list discussion of valgrind with the GC around March 8 of this year.

I personally haven't found leak detectors that check for unmatched mallocs (which I believe is what valgrind reports) very useful with C code, which usually doesn't free() permanent data structures (and hence tends to shut down faster than C++ code, which often does).  But your mileage will vary.  I think most of the interest in the valgrind + gc combination was for other reasons.

Hans

From: abhishek goswami [mailto:zeal_goswami at yahoo.com]
Sent: Thursday, October 04, 2012 10:17 PM
To: Boehm, Hans; gc at linux.hpl.hp.com
Subject: Re: [Gc] Log Analysis of GC

Hi,
I have visited wiki. After Adding GC_Collect, I was getting informative information. MeanWhile I am using Linux OS sytem
Can you please also provide me input to integrate Valgrind with Garbage Collector.I have tried to run test case but always got segementation fault.

As per existing system,we use valgrind to identify memory leak. I decided to  use Garbage collector into my existing code base to reduce memory
leak.I want to verify  with valgrind which help me a lot to choose GC_Collect for major modification into existing system.

Although, I have gone another wiki page which gave me information that we can not use valgrind with GC. is it true? if yes, do we have any workaround
to verify the total memory leak.

Abhishek Goswami
Chennai
Phone No -09962270999
From: "Boehm, Hans" <hans.boehm at hp.com>
To: abhishek goswami <zeal_goswami at yahoo.com>; "gc at linux.hpl.hp.com" <gc at linux.hpl.hp.com>
Sent: Friday, 5 October 2012 5:21 AM
Subject: RE: [Gc] Log Analysis of GC

Did you see http://www.hpl.hp.com/personal/Hans_Boehm/gc/leak.html?  Which directions did you follow?  Which OS and compiler are you using?

You should be getting more information about the objects being leaked, as illustrated on the above web page.  But that requires that you use some mechanism that redirects malloc() to a debugging malloc version, so that some allocation context is remembered in the object, and you get more informative messages.

Hans

From: gc-bounces at linux.hpl.hp.com [mailto:gc-bounces at linux.hpl.hp.com] On Behalf Of abhishek goswami
Sent: Wednesday, October 03, 2012 10:31 PM
To: gc at linux.hpl.hp.com
Subject: [Gc] Log Analysis of GC

Hi,
I have configured GC collector and leak detector also into my code. When I run the execute .  I got the message into my stderr in following way. Can anyone provide me some input.I am not able to figure out where is issue exist?.

Leaked composite object at start: 0x8941000, appr. length: 2048
Leaked composite object at start: 0x8941800, appr. length: 2048
Leaked composite object at start: 0x893f000, appr. length: 2048
Leaked composite object at start: 0x893f800, appr. length: 2048
Leaked composite object at start: 0x893e000, appr. length: 2048
Leaked composite object at start: 0x893e800, appr. length: 2048
Leaked composite object at start: 0x893c000, appr. length: 2048
Leaked composite object at start: 0x893c800, appr. length: 2048
Leaked composite object at start: 0x893b000, appr. length: 2048
Leaked composite object at start: 0x893b800, appr. length: 2048
Leaked composite object at start: 0x893a800, appr. length: 2048


Generally we check the memory leak with valgrind with our code base. I tried to simulate valgrind with GC but end up with segmentation fault.
is there any workaround so that I can use valgridn with GC or any other tool which help to identify the leak if any.

As of now,I am using GC leak detector for finding the memory leak but got the above message which does not contain any useful information.




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