release-19.1: storage: avoid copying marshalled RaftCommand when encoding #36670
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Informs cockroachdb#36347. This change avoids the unnecessary allocation and memory copy present in Raft command encoding. This extra work is expensive for large commands like `AddSSTable` requests. Even for smaller requests, this work was still a serious problem because it took place under heavily contended locks. For instance, the encoding in `defaultSubmitProposalLocked` took place under the Replica mutex, which serializes all Raft proposals for a Range. The other two locations fixed took place under the Raft mutex. While less heavily contended, this was still slowing down the Raft processing goroutine. This is a less dramatic version of a change I've been working on. The full change lifts the slice allocation and most of the RaftCommand proto marshalling all the way out of `defaultSubmitProposalLocked` and out of the `Replica.mu` critical section. This commit gets us part of the way there sets the stage for the rest of the change. Release note: None
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ajwerner
approved these changes
Apr 9, 2019
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Reviewed 5 of 5 files at r1.
Reviewable status:complete! 0 of 0 LGTMs obtained (waiting on @dt)
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Backport 1/1 commits from #36392.
/cc @cockroachdb/release
Informs #36347.
This change avoids the unnecessary allocation and memory copy present in
Raft command encoding. This extra work is expensive for large commands
like
AddSSTablerequests. Even for smaller requests, this work wasstill a serious problem because it took place under heavily contended
locks. For instance, the encoding in
defaultSubmitProposalLockedtookplace under the Replica mutex, which serializes all Raft proposals for
a Range. The other two locations fixed took place under the Raft mutex.
While less heavily contended, this was still slowing down the Raft
processing goroutine.
This is a less dramatic version of a change I've been working on. The
full change lifts the slice allocation and most of the RaftCommand proto
marshalling all the way out of
defaultSubmitProposalLockedand out ofthe
Replica.mucritical section. This commit gets us part of the waythere sets the stage for the rest of the change.
Release note: None