EPICS Base

Race in db_close_events()

Bug #1730982 reported by mdavidsaver on 2017-11-08

This bug affects 3 people

	Status	Importance	Assigned to	Milestone
EPICS Base	Status tracked in 7.0
3.14	Won't Fix	Low	Ralph Lange	EPICS Base 3.14.12.8
3.15	Fix Released	Undecided	Unassigned
3.16	Fix Released	Undecided	Unassigned
7.0	Fix Released	Low	mdavidsaver

Bug Description

valgrind reports a data race in db_close_events(). This is the pattern of:

> epicsEventMustWait(...)
> epicsEventDestroy(...)

Where the working calling 'epicsEventSignal(...)' may not have returned before the event is destroy'd.

I introduced this race in d2b0e920012d4c9bc0eaecc0e092cedd776db578 prior to 3.15.0.1 to fix a similar race (the worker was calling epicsEventDestroy() ).

We need a safe pattern for joining worker threads (cf. lp:1699229).