release-21.1: kvccl: re-order enterprise check in canSendToFollower #62606
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Fixes cockroachdb#62447. In cockroachdb#62447, Erik found that cockroachdb#59571 had re-ordered the call to `utilccl.CheckEnterpriseEnabled` to occur before checking the batch in `canSendToFollower`, instead of after. This added an error allocation into the hot path of all reads, which showed up in CPU profiles and caused an 8% performance regression on `kv95`. This commit fixes this by moving the enterprise check back out of the hot-path for all non-stale read-only batches. A follow up to this PR would be to make `utilccl.CheckEnterpriseEnabled` cheaper by avoiding the error allocation for callers that don't need an error. This work is not done in this commit.
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erikgrinaker
approved these changes
Mar 25, 2021
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Backport 1/1 commits from #62465.
/cc @cockroachdb/release
Fixes #62447.
In #62447, Erik found that #59571 had re-ordered the call to
utilccl.CheckEnterpriseEnabledto occur before checking the batch incanSendToFollower, instead of after. This added an error allocationinto the hot path of all reads, which showed up in CPU profiles and
caused an 8% performance regression on
kv95. This commit fixes this bymoving the enterprise check back out of the hot-path for all non-stale
read-only batches.
A follow up to this PR would be to make
utilccl.CheckEnterpriseEnabledcheaper by avoiding the error allocation for callers that don't need an
error. This work is not done in this commit.