Make ScheduleClose() idempotent #445
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I think this fixes issue eventmachine#441. 8b613d0 changed the `select` timeout to zero in the case where NumCloseScheduled > 0. It seems that in certain circumstances (for example, if `close_connection` is called in a connection's `unbind`) NumCloseScheduled would get incremented twice, but only decremented once, thus never again reaching zero for the lifetime of the reactor. The user-observed effect was that one CPU core would be pegged at 100%, because the zero `select` timeout caused us to go around the select loop without any pause. Changing it so that it is safe to ScheduleClose() multiple times seems like the cleanest solution to the problem.
This was referenced Jun 3, 2013
This was referenced Feb 25, 2015
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I think this fixes issue #441.
8b613d0 changed the
selecttimeout to zero in the case whereNumCloseScheduled > 0. It seems that in certain circumstances (for example, ifclose_connectionis called in a connection'sunbind)NumCloseScheduledwould get incremented twice, but only decremented once, thus never again reaching zero for the lifetime of the reactor.The user-observed effect was that one CPU core would be pegged at 100%, because the zero
selecttimeout caused us to go around the select loop without any pause.Changing it so that it is safe to call
ScheduleClose()multiple times seems like the cleanest solution to the problem.