[petsc-dev] VecScatter problem

[Abbott, Stephen R.]

>> If there was an error then you should have seen PETSc output to that effect.  Could you have missed that?

I don’t see any error show up in the output, and the run continues happily even with the error checks in place, so I don’t think that’s it.

>> You should definitely add these error check, but that gets rid of the error!

I agree completely, they should be there. I would be much more comfortable if just putting them in didn’t solve the error I put them in to look for..

>> Could this be a compiler error?

We’re using the PGI compiler, and I’ve tried it with versions 16.5 (with your PETSc builds) and 15.10 (with the cray-petsc-3.7 build) and seen the same problem. But, yes, this could definitely be a compiler error. I’m rebuilding the code with optimizations disabled to run the memory checking, so I’ll have a chance to see if maybe the compiler is making a mistake there.

Does PETSc’s logging count VecScatter calls and messages passed? Maybe I can look at the logs and compare counts for a working run to a broken run and see if those last two scatters are getting optimized out.

--steve

On 8/25/16, 5:48 PM, "Mark Adams" <mfadams at lbl.gov<mailto:mfadams at lbl.gov>> wrote:



The troubling bit about this, which caused me to suggest that it was a race condition, was that if I modify the code a little bit I can get the correct result from the scatter. For example, we weren’t always checking the returned error flag.

If there was an error then you should have seen PETSc output to that effect.  Could you have missed that?

You should definitely add these error check, but that gets rid of the error!  Could this be a compiler error?

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