If you increase the log level, for instance set
SlurmctldDebug=debug DebugFlags=Backfill you might get more information about what happens. If it is the backfilling that takes too long, you should see messages about backfill "yielding locks". If I recall correctly, the backfill scheduler used to time out after MessageTimeout/2 seconds, but looking at the code for 2.5.6 this seems to have changed. Keep us posted about what you find. I'm planning to switch to 2.5.6 tomorrow, and have from time to time had problems getting the backfilling to be fast enough. -- Regards, Bjørn-Helge Mevik, dr. scient, Department for Research Computing, University of Oslo
