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From "Rana Dasgupta" <rdasg...@gmail.com>
Subject Re: [drlvm][GC]Bad Pointer during GC v5 shutdown sequence
Date Sat, 10 Nov 2007 19:13:53 GMT
Illya,
Yes, it's possible that there could be a leak. An assert added to
vm_unmap_mem() does show that the VirtualFree fails. The pointer parameter
etc. passed to the function are invalid because the sections of the heap (
nos, mos etc. ) have already been freed with STD_FREE.
 The root cause is that for VirtualFree() to successfully release on
Windows, it needs to be called from the exact VirtualAlloc allocation base.
I have attached a quick fix in
H5105<https://issues.apache.org/jira/browse/HARMONY-5105>
which you can try. Xiao Feng needs to look at it.

Rana

 On Nov 9, 2007 9:40 AM, Ilya Leviev <ilya.leviev@gmail.com> wrote:
> Hello Harmony people,
>
> I want to improve DRLVM reliability for EIOffice application. I have a
> licensed BoundsChecker tool on my computer and decided to use it as a
> first step.
>
> I have profiled a simple EIOffice application on Harmony using
> BoundsChecker and the tool detected ~300MB of memory leaks. The
> largest leak (256 Mb) was caused by passing invalid parameter to
> VirtualFree() function call the shutdown of GC v5.
>
>  This function fails to free memory that was allocated by VirtualAlloc
> at GC initialization function:
>
> gc_init()->
>
>   gc_gen_initialize((GC_Gen*)gc, min_heap_size_bytes, max_heap_size_bytes)

>
>            vm_reserve_mem(void* start, POINTER_SIZE_INT size)
>
>                     address = VirtualAlloc(start, size, MEM_RESERVE,
> PAGE_READWRITE)
>
> My investigation shows that memory is not disposed because
> VirtualFree() call at vm_unmap_mem() fails. VirtualFree returns zero
> that means the function failure. The reason for this is the invalid
> pointer parameter which is passed to the function. This issue of bad
> pointers was detected by BoundsChecker.
>
>
> I have succeeded to reproduce this GC v5 issue running "Hello, World"
> Application (HWA) too. However when I profiled HWA using GC V4 no GC
> memory leak was detected and it frees memory correctly.
>
>
> So currently I'm thinking if a correct shutdown of GC v5 is important
> for reliability. I believe it is because we have enough problems
> related to thread termination on shutdown, and having clear shutdown
> for components with simpler lifecycle would simplify the whole
> shutdown cleanup task.
>
> Thanks!
> Ilya Leviev
> ESSD, Intel
>

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