This is on master snapshot as of a few weeks ago.
Haven't looked at the code much yet, but it seems rather fundamental. The procedure comes from meta replica assignment (HBASE-21624), in case it matters w.r.t. the engine initialization; however, the master is functional and other procedures run fine. I can also see lots of other open region procedures with a similar patterns that were initialized before this one and have run fine.
Currently, there are no other runnable procedures on master - a lot of succeeded procedures since then, the parent blocked on this procedure, and one unrelated RIT procedure waiting with timeout and being updated periodically.
The procedure itself is
This is in PST so it's been like that for ~19 hours.
The only line involving this PID in the log is
There are no other useful logs for either this PID, parent PID, or region in question since. This PEWorker (4) is also alive and did some work since then, so it's not like the thread errored out somewhere.
All the PEWorker-s are waiting for work:
The main assignment procedure for this region is blocked on it: