Hi, I forgot to register a display name for LWTRANCHE_PARALLEL_HASH_JOIN, the tranche ID used by the LWLock that Parallel Hash uses when handing out chunks of memory. Please see attached.
It's rare for this LWLock to show up in pg_stat_activity, but if you stick pg_usleep(10000) into ExecParallelHashTupleAlloc() after the lock is acquired (the slow path where a new 32KB chunk is needed) and run some parallel hash joins, then you'll see that pg_stat_activity reports that as "extension" in unpatched master. -- Thomas Munro http://www.enterprisedb.com
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