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tikv: eliminate unnecessary pessimistic rollback (#12561) #12707

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merged 3 commits into from Oct 30, 2019

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@sre-bot sre-bot commented Oct 15, 2019

cherry-pick #12561 to release-3.0


Signed-off-by: youjiali1995 zlwgx1023@gmail.com

What problem does this PR solve?

When acquiring pessimistic locks fails, we do async pessimistic rollback to clean up all locks even some of them are not locked. These rollback operations will conflict with the following lock operations which may reduce performance.

What is changed and how it works?

If there is only 1 key and lock failed, no need to do pessimistic rollback.

sysbench oltp_write_only, tables: 32*100, threads: 128

Before

SQL statistics:
    queries performed:
        read:                            0
        write:                           28523
        other:                           14900
        total:                           43423
    transactions:                        5859   (47.05 per sec.)
    queries:                             43423  (348.71 per sec.)
    ignored errors:                      3182   (25.55 per sec.)
    reconnects:                          0      (0.00 per sec.)

General statistics:
    total time:                          124.5217s
    total number of events:              5859

Latency (ms):
         min:                                    1.77
         avg:                                 2694.71
         max:                                33254.30
         95th percentile:                     9624.59
         sum:                             15788288.77

This PR

SQL statistics:
    queries performed:
        read:                            0
        write:                           342892
        other:                           179245
        total:                           522137
    transactions:                        70701  (235.34 per sec.)
    queries:                             522137 (1737.99 per sec.)
    ignored errors:                      37843  (125.96 per sec.)
    reconnects:                          0      (0.00 per sec.)

General statistics:
    total time:                          300.4248s
    total number of events:              70701

Latency (ms):
         min:                                    1.88
         avg:                                  543.52
         max:                                 8555.44
         95th percentile:                     1561.52
         sum:                             38427743.18

Check List

Tests

  • No code

Code changes

Side effects

Related changes

  • Need to cherry-pick to the release branch

Release note

  • Improve the performance of the pessimistic transaction in some situations with serious conflicts.

Signed-off-by: youjiali1995 <zlwgx1023@gmail.com>
Signed-off-by: youjiali1995 <zlwgx1023@gmail.com>
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sre-bot commented Oct 15, 2019

/run-all-tests

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@coocood coocood left a comment

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LGTM

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@MyonKeminta MyonKeminta left a comment

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LGTM

@zz-jason zz-jason added status/can-merge Indicates a PR has been approved by a committer. status/LGT2 Indicates that a PR has LGTM 2. labels Oct 30, 2019
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sre-bot commented Oct 30, 2019

Your auto merge job has been accepted, waiting for 13036, 13039, 13031, 12960, 12962, 12900, 12901, 12902, 12708

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sre-bot commented Oct 30, 2019

/run-all-tests

@sre-bot sre-bot merged commit 5cb5162 into pingcap:release-3.0 Oct 30, 2019
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5 participants