storage: use FIFO order in queues on equal priorities #32053
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This is a refactor without functional changes, in preparation for adding a sequence number generator into the priority queue. Release note: None
When priorities are equal, the priority queue naively performs close to LIFO which is not what we want as it allows starvation of items backed into the queue. This poses a big problem for the Raft snapshot queue when put under pressure. See cockroachdb#31947 (comment). Release note (bug fix): Avoid a stall in the processing of Raft snapshots when many snapshots are requested at the same time.
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petermattis
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Oct 31, 2018
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Looks exactly like what I was imagining.
Reviewed 2 of 2 files at r1.
Reviewable status:complete! 0 of 0 LGTMs obtained (and 1 stale)
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32053: storage: use FIFO order in queues on equal priorities r=petermattis a=tschottdorf When priorities are equal, the priority queue naively performs close to LIFO which is not what we want as it allows starvation of items backed into the queue. This poses a big problem for the Raft snapshot queue when put under pressure. See #31947 (comment). Release note (bug fix): Avoid a stall in the processing of Raft snapshots when many snapshots are requested at the same time. Co-authored-by: Tobias Schottdorf <tobias.schottdorf@gmail.com>
We need to get to the bottom of what is causing the snapshot generation. |
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Which I'm sure you're already doing. |
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One failed run at a time. |
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When priorities are equal, the priority queue naively performs close to
LIFO which is not what we want as it allows starvation of items backed into
the queue. This poses a big problem for the Raft snapshot queue when put
under pressure.
See
#31947 (comment).
Release note (bug fix): Avoid a stall in the processing of Raft snapshots
when many snapshots are requested at the same time.