Thanks - that made me look more closely. The issue was the 'sim.plot2D' call that I had for only 'am_master()', because I had misunderstood that section as 'you should do plotting only for master', as opposed to just the external lib calls (matplotlib).
Then the 'print' simply hadn't gotten serialized out to output yet. Moving 'sim.plot2D' outside of 'am_master' completely resolved this. Thanks again! Sorry for the hassle. On Wed, Dec 2, 2020 at 8:33 PM Ardavan Oskooi <ardavan.osk...@gmail.com> wrote: > This type of behavior is usually due to one of the MPI processes > deadlocking due to a run function or similar that is called at the end of > the time stepping in which a field routine > <https://meep.readthedocs.io/en/latest/Python_User_Interface/#field-computations> > (e.g., get_field_point, etc.) is called from within "if meep.am_master():". > This issue is described in the Features/Parallel Meep/Technical Details > <https://meep.readthedocs.io/en/latest/Parallel_Meep/#technical-details> > in the paragraph starting with "Warning: Most Meep functions operating on > the simulation...". > > However, this doesn't seem to apply in your case. > On 12/2/20 19:13, Luke Durant wrote: > > I have a very simple simulation (almost identical to the > GaussianBeamSource example), but when I run with MPI (local node only, > multi-core) it hangs before returning from 'sim.run(until=60)'. > > The simulation appears to proceed correctly until the sim should be > complete: > ' > ... > Meep progress: 45.56/60.0 = 75.9% done in 16.0s, 5.1s to go > on time step 4556 (time=45.56), 0.0034461 s/step > Meep progress: 57.18/60.0 = 95.3% done in 20.0s, 1.0s to go > on time step 5718 (time=57.18), 0.00344415 s/step > ' [Hang forever]. > > It hangs with 2 threads or 32 threads (Ryzen 3990x CPU). Performance > scales apparently correctly through the simulation otherwise (2 threads is > 2x serial; 32 again much faster). > > >
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