Starting with Darshan 3.2.0, there appear to be hangs at Darshan shutdown time in some cases, resulting in output like:

darshan_library_warning: unable to write header to file /share/home/hpcuser/darshan_logs/hpcuser_ior_id26_9-18-65156-2174583250033636718.darshan_partial.

I've confirmed the behavior with Darshan master and mvapich2-3.2.3 and mvapich2-3.2.4.

Reported by Cormac Garvey.