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On Thu, May 2, 2024 at 12: 53 PM Samar Khatiwala <samar. khatiwala@ earth. ox. ac. uk> wrote: Hello, I have a couple of questions about createWithArray in petsc4py: 1) What is the correct usage for creating a standard MPI Vec with it? Something
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<div dir="ltr"><div dir="ltr">On Thu, May 2, 2024 at 12:53 PM Samar Khatiwala <<a href="mailto:samar.khatiwala@earth.ox.ac.uk">samar.khatiwala@earth.ox.ac.uk</a>> wrote:<br></div><div class="gmail_quote"><blockquote class="gmail_quote" style="margin:0px 0px 0px 0.8ex;border-left:1px solid rgb(204,204,204);padding-left:1ex"><div class="msg1959822169370491940"><u></u>
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Hello, I have a couple of questions about createWithArray in petsc4py: 1) What is the correct usage for creating a standard MPI Vec with it? Something like this seems to work but is it right?: On each rank do: a = np. zeros(localSize) v = PETSc. Vec(). createWithArray(a,
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<div><pre style="font-family:sans-serif;font-size:100%;white-space:pre-wrap">Hello,
I have a couple of questions about createWithArray in petsc4py:
1) What is the correct usage for creating a standard MPI Vec with it? Something like this seems to work but is it right?:
On each rank do:
a = np.zeros(localSize)
v = PETSc.Vec().createWithArray(a, comm=PETSc.COMM_WORLD)
Is that all it takes?</pre></div></div></blockquote><div><br></div><div>That looks right to me.</div><blockquote class="gmail_quote" style="margin:0px 0px 0px 0.8ex;border-left:1px solid rgb(204,204,204);padding-left:1ex"><div class="msg1959822169370491940"><div><pre style="font-family:sans-serif;font-size:100%;white-space:pre-wrap">2) Who ‘owns’ the underlying memory for a Vec created with the createWithArray method, i.e., who is responsible for managing it and doing garbage collection? In my problem, the numpy array is created in a Cython module where memory is allocated, and a pointer to it is associated with a numpy ndarray via PyArray_SimpleNewFromData and PyArray_SetBaseObject. I have a deallocator method of my own that is called when the numpy array is deleted/goes out of scope/whenever python does garbage collection. All of that works fine. But if I use this array to create a Vec with createWithArray what happens when the Vec is, e.g., destroyed? Will my deallocator be called? </pre></div></div></blockquote><div>No. The PETSc struct will be deallocated, but the storage will not be touched. </div><div><br></div><div> Thanks,</div><div><br></div><div> Matt</div><blockquote class="gmail_quote" style="margin:0px 0px 0px 0.8ex;border-left:1px solid rgb(204,204,204);padding-left:1ex"><div class="msg1959822169370491940"><div><pre style="font-family:sans-serif;font-size:100%;white-space:pre-wrap">Or does petsc4py know that it doesn’t own the memory and won’t attempt to free it? I can’t quite figure out from the petsc4py code what is going on. And help would be appreciated.
Thanks very much.
Samar
</pre></div>
</div></blockquote></div><br clear="all"><div><br></div><span class="gmail_signature_prefix">-- </span><br><div dir="ltr" class="gmail_signature"><div dir="ltr"><div><div dir="ltr"><div><div dir="ltr"><div>What most experimenters take for granted before they begin their experiments is infinitely more interesting than any results to which their experiments lead.<br>-- Norbert Wiener</div><div><br></div><div><a href="https://urldefense.us/v3/__http://www.cse.buffalo.edu/*knepley/__;fg!!G_uCfscf7eWS!anRKQn_8v127_CSkzk22FfTFRodKT0G2BLwgi_kPAUQt_eqCiySYWSg3ctwewCceXLeJY4FU01ONUBwNdAR2$" target="_blank">https://www.cse.buffalo.edu/~knepley/</a><br></div></div></div></div></div></div></div></div>