<html><head><meta http-equiv="content-type" content="text/html; charset=utf-8"></head><body style="overflow-wrap: break-word; -webkit-nbsp-mode: space; line-break: after-white-space;"><div><br></div> I don't fully understand your code and what it is trying to demonstrate, but VecGetArrayWrite is Logically Collective. Having <div><br></div><div><div> if(rank == 0)</div><div> {</div><div> PetscCall(VecGetArrayWrite(vec, &xx));</div><div> PetscCall(VecRestoreArrayWrite(vec, &xx));</div><div> }</div><div><br></div><div>is not allowed. The reason is that VecRestoreArrayWrite() changes the PetscObjectState of the vector, and this state must be changed consistently across all MPI processes that share the vector. </div><div><br></div><div><br></div><div><br><blockquote type="cite"><div>On Dec 10, 2023, at 2:40 AM, Stephan Köhler <stephan.koehler@math.tu-freiberg.de> wrote:</div><br class="Apple-interchange-newline"><div>
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Dear PETSc/Tao team,
<br>
<br>
there is a bug in the voector interface: In the function
<br>
VecNorm, see, eg.
<a class="moz-txt-link-freetext" href="https://petsc.org/release/src/vec/vec/interface/rvector.c.html#VecNorm">https://petsc.org/release/src/vec/vec/interface/rvector.c.html#VecNorm</a>
line 197 the check for consistency in line 214 is done on the wrong
communicator. The
communicator should be PETSC_COMM_SELF.<br>
<span _d-id="11028" class="--l --r sentence_highlight">Otherwise the
program may hang when PetscCheck is executed.<br>
<br>
Please find a minimal example attached.<br>
</span><br>
<br>
Kind regards,
<br>
Stephan Köhler
<pre class="moz-signature" cols="72">--
Stephan Köhler
TU Bergakademie Freiberg
Institut für numerische Mathematik und Optimierung
Akademiestraße 6
09599 Freiberg
Gebäudeteil Mittelbau, Zimmer 2.07
Telefon: +49 (0)3731 39-3188 (Büro)</pre>
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<span id="cid:4C263B6C-2FD3-431F-9AF3-2B6A53743543"><minimal_ex_vec_norm.cpp></span><span id="cid:544E075A-D2D1-461E-B245-E2D57B37CD3F"><OpenPGP_0xC9BF2C20DFE9F713.asc></span></div></blockquote></div><br></div></body></html>