[dune-pdelab] Memory leak problem with BCGS_AMG_SSOR linear solver for parallel computations

[Shubhangi Gupta]

Dear all,

I am trying to simulate a time-dependent PDE on a fairly large 2D domain.

I use the BCGS_AMG_SSOR linear solver for parallel computations, in 
combination with Newton method,
     Dune::PDELab::ISTLBackend_BCGS_AMG_SSOR<IGO> LS;
     LS ls(gfs,5000,0, _/false/_, true);

I am using dune 2.4 version.
I noticed that if I do not reuse the matrix in LS then I experience 
massive memory leaks. For reference, I have 64 GB RAM and a swap of 128 
GB, and even then I run out of memory within just a quarter way through 
my simulation!
But if I reuse the matrix (i.e., LS ls(gfs,5000,0, _/true/_, true)), I 
no longer get the memory leak issue, but the simulation becomes 
painfully slow. It starts out at normal speed, but gets progressively 
slower, to a point where it is essentially useless.

Is this normal? I am wondering if anyone can suggest a fix or an 
alternative for my problem.

Thanks in advance,
warm wishes, Shubhangi

-- 
Dr. Shubhangi Gupta
Marine Geosystems
GEOMAR Helmholtz Center for Ocean Research
Wischhofstraße 1-3,
D-24148 Kiel

Room: 12-206
Phone: +49 431 600-1402
Email:sgupta at geomar.de

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