Hi,

I am trying to figure out if there is a memory leak or a lack of understanding 
on my part
with respect to the HDF5 internals. My simple test case writes a 4-dimensional 
uniformly
distributed array using H5Dwrite. I measure the heap memory before and after 
the write.
I would expect the heap memory utilization to not change substantially.

I have measured the heap memory a couple of different ways, e.g. using mallinfo 
or some tool.
Naively it looks like the MPI I/O aggregators are not releasing memory but some 
tools
have reported no leak at all, while others have report a large one (> 200 MB). 
I finally
resorted to using mpirun -strace to track the series of mmap/munmap in the 
H5Dwrite.
I was surprised to see a large number of calls to mmap/munmap which ultimately 
results
in 60 MB of heap memory not being released.

First question: Is this the intended behavior?

Second question: If this behavior is intentional, is there away to force HDF5 
to release
these internal buffers after the H5Dwrite.

Nichols A. Romero, Ph.D.
Argonne Leadership Computing Facility
Argonne National Laboratory
Building 240 Room 2-127
9700 South Cass Avenue
Argonne, IL 60490
(630) 252-3441



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