[petsc-dev] MATOP_MAT_MULT

[Zhang, Hong]

Pierre,
When we do
MatProductCreate: C = A*B; //C owns A and B, thus B->refct =2
MatProductCreateWithMats: B = A*C; //If I let B own A and C, then C->refct=2
Then
MatDestroy(&B) and MatDestroy(&C) only reduce their refct from 2 to 1, thus memory leak.
My solution is adding
{
           matreference;  /* do not add refct when using MatProductCreateWithMat() to void recursive references */
} Mat_Product
This flg prevents MatProductCreateWithMats() to increase reference counts, i.e., B does not own A and C to avoid reverse ownership. I am not sure this is a reasonable solution. Let me know if you have better solution.
See ex109.c and ex195.c for tests.
Hong
________________________________
From: Pierre Jolivet <pierre.jolivet at enseeiht.fr>
Sent: Saturday, April 25, 2020 11:45 AM
To: Zhang, Hong <hzhang at mcs.anl.gov>
Cc: Jose E. Roman <jroman at dsic.upv.es>; Stefano Zampini <stefano.zampini at gmail.com>; petsc-dev <petsc-dev at mcs.anl.gov>; Smith, Barry F. <bsmith at mcs.anl.gov>
Subject: Re: [petsc-dev] MATOP_MAT_MULT

Hong,
José didn’t report this, though he may have run into the same issue, I did.
I’ll try the branch and get back at you on GitLab MR.

Thanks,
Pierre

On 25 Apr 2020, at 6:17 PM, Zhang, Hong <hzhang at mcs.anl.gov<mailto:hzhang at mcs.anl.gov>> wrote:

Jose,

>> I also now just tested some previously PETSC_VERSION_LT(3,13,0) running code with C=A*B, Dense=Nest*Dense, all previously allocated prior to a call to MatMatMult and scall = MAT_REUSE_MATRIX.
>> Sadly, it’s now broken. It is my fault for not having a test for this in https://gitlab.com/petsc/petsc/-/merge_requests/2069, sorry about that.
>> [0]PETSC ERROR: Call MatProductSymbolic() first
>> [0]PETSC ERROR: #1 MatProductNumeric() line 730 in /ccc/work/cont003/rndm/rndm/petsc/src/mat/interface/matproduct.c
>> [0]PETSC ERROR: #2 MatMatMult() line 9335 in /ccc/work/cont003/rndm/rndm/petsc/src/mat/interface/matrix.c
>>
>> Here is a reproducer (that will work OK with 3.12.4).
>> diff --git a/src/mat/tests/ex195.c b/src/mat/tests/ex195.c
>> index c72662bc3c..811de669c5 100644
>> --- a/src/mat/tests/ex195.c
>> +++ b/src/mat/tests/ex195.c
>> @@ -73,2 +73,3 @@ int main(int argc,char **args)
>>    ierr = MatMatMult(nest,B,MAT_REUSE_MATRIX,PETSC_DEFAULT,&C);CHKERRQ(ierr);
>> +  ierr = MatMatMult(nest,C,MAT_REUSE_MATRIX,PETSC_DEFAULT,&B);CHKERRQ(ierr);
>>    ierr = MatMatMultEqual(nest,B,C,10,&equal);CHKERRQ(ierr);
>>
>> $ make -f gmakefile test searchin=mat_tests-ex195
>>
>> I believe this is very close to the topic at hand and issue #608, so maybe you could fix this as well in the same upcoming MR? Just let me know, I can have a crack it otherwise.

This is a bug. I fixed it in the branch hzhang/fix-matproduct-reuse/maint. Can you test it?
Hong

-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://lists.mcs.anl.gov/pipermail/petsc-dev/attachments/20200425/0f313ecf/attachment.html>