Synchronize pendingOutgoingJoins #39900
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Today we use a ConcurrentHashSet to track the in-flight outgoing joins in the `JoinHelper`. This is fine for adding and removing elements but not for the emptiness test in `isJoinPending()` which might return false if one join finishes just after another one starts, even though joins were pending throughout. As used today this is ok: it means the node was trying to join a master but this join attempt just finished unsuccessfully, and causes it to (rightfully) reject a `FollowerCheck` from the failed master. However this kind of API inconsistency is trappy and there is no need to be clever here, so this change replaces the set with a synchronizedSet().
DaveCTurner
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>non-issue
v7.0.0
:Distributed Coordination/Cluster Coordination
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henningandersen
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Mar 11, 2019
DaveCTurner
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Mar 11, 2019
Today we use a ConcurrentHashSet to track the in-flight outgoing joins in the `JoinHelper`. This is fine for adding and removing elements but not for the emptiness test in `isJoinPending()` which might return false if one join finishes just after another one starts, even though joins were pending throughout. As used today this is ok: it means the node was trying to join a master but this join attempt just finished unsuccessfully, and causes it to (rightfully) reject a `FollowerCheck` from the failed master. However this kind of API inconsistency is trappy and there is no need to be clever here, so this change replaces the set with a `synchronizedSet()`.
DaveCTurner
added a commit
that referenced
this pull request
Mar 11, 2019
Today we use a ConcurrentHashSet to track the in-flight outgoing joins in the `JoinHelper`. This is fine for adding and removing elements but not for the emptiness test in `isJoinPending()` which might return false if one join finishes just after another one starts, even though joins were pending throughout. As used today this is ok: it means the node was trying to join a master but this join attempt just finished unsuccessfully, and causes it to (rightfully) reject a `FollowerCheck` from the failed master. However this kind of API inconsistency is trappy and there is no need to be clever here, so this change replaces the set with a `synchronizedSet()`.
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Today we use a ConcurrentHashSet to track the in-flight outgoing joins in the
JoinHelper. This is fine for adding and removing elements but not for theemptiness test in
isJoinPending()which might return false if one joinfinishes just after another one starts, even though joins were pending
throughout.
As used today this is ok: it means the node was trying to join a master but
this join attempt just finished unsuccessfully, and causes it to (rightfully)
reject a
FollowerCheckfrom the failed master. However this kind of APIinconsistency is trappy and there is no need to be clever here, so this change
replaces the set with a
synchronizedSet().