fix: avoid race condition when reconnecting #2716
Open
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Background
We have been seeing occasional
Connection is aborted
errors when pausing a Bull queue that is backed by Redis in cluster mode. The investigation led to this fix inioredis
. After deploying that fix, the errors became a lot more rare, but they still pop up from time to time - sometimes days apart.The debug logs from
ioredis
led me to believe that the issue may be around howbull
re-establishes the blocking connection whenpause()
is called. Specifically, the promise returned byredisClientDisconnect
may get resolved before this disconnect() call is executed, causingioredis
to abort its already ongoing connection attempt.Attempts to reliably reproduce the bug have led to this repository where
ioredis
is intentionally modified to slightly delay the resolution of the promise returned from the Redis cluster client'squit()
method in order to provoke the bug into occurring. All that is then necessary is to create a queue and repeatedly pause/resume it.Change
Avoids calling
client.disconnect()
withinredisClientDisconnect
if the promise is already resolved at that point.