tikv: eliminate unnecessary pessimistic rollback #12561
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Signed-off-by: youjiali1995 <zlwgx1023@gmail.com>
youjiali1995
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component/tikv
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coocood
reviewed
Oct 9, 2019
store/tikv/txn.go
Outdated
| // Sleep a little, wait for the other transaction that blocked by this transaction to acquire the lock. | ||
| time.Sleep(time.Millisecond * 5) | ||
| // If there is only 1 key and lock failed, no need to do pessimistic rollback. | ||
| if len(keys) > 1 { |
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We need to make sure the err indicates the lock must not be locked to skip pessimistic rollback.
Signed-off-by: youjiali1995 <zlwgx1023@gmail.com>
Codecov Report
@@ Coverage Diff @@
## master #12561 +/- ##
===========================================
Coverage 79.9092% 79.9092%
===========================================
Files 462 462
Lines 104934 104934
===========================================
Hits 83852 83852
Misses 14892 14892
Partials 6190 6190 |
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@coocood PTAL again. Thanks. |
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LGTM |
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@tiancaiamao PTAL |
MyonKeminta
reviewed
Oct 10, 2019
| wg.Wait() | ||
| // Sleep a little, wait for the other transaction that blocked by this transaction to acquire the lock. | ||
| time.Sleep(time.Millisecond * 5) | ||
| keyMayBeLocked := terror.ErrorNotEqual(kv.ErrWriteConflict, err) && terror.ErrorNotEqual(kv.ErrKeyExists, err) |
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I'm afraid if we add more error types or changes our usage of these error types in the future, this may fail.
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That is why it use ErrorNotEqual here. As long as we make sure ErrWriteConflict and ErrKeyExists won't lock the key.
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LGTM |
coocood
approved these changes
Oct 10, 2019
coocood
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status/can-merge
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Your auto merge job has been accepted, waiting for 12322 |
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/run-all-tests |
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/bench |
@@ Benchmark Diff @@
================================================================================
--- tidb: 394505b53aa747f2a4dce8a735cebb65ccf97cb9
+++ tidb: 179bacf3159875d3f3983f44e15d8e986be4eecc
tikv: 8cfeb1a1c1bf1194d10ebab3c9e98e084b2d2d46
pd: 2550168c27878a33a8465a72bafdc534e409b60a
================================================================================
test-1: < oltp_point_select >
* QPS : 79077.94 ± 0.3341% (std=210.47) delta: 2.74% (p=0.198)
* AvgMs : 3.24 ± 0.3086% (std=0.01) delta: -2.56%
* PercentileMs99 : 6.62 ± 2.5370% (std=0.10) delta: -1.78%
test-2: < oltp_read_write >
* QPS : 38381.48 ± 0.5853% (std=153.58) delta: 0.41% (p=0.142)
* AvgMs : 133.96 ± 0.5987% (std=0.54) delta: -0.38%
* PercentileMs99 : 257.95 ± 0.0000% (std=0.00) delta: 0.00%
test-3: < oltp_insert >
* QPS : 22199.54 ± 0.6677% (std=100.56) delta: 0.77% (p=0.303)
* AvgMs : 11.53 ± 0.6766% (std=0.05) delta: -0.77%
* PercentileMs99 : 23.35 ± 1.0791% (std=0.21) delta: -0.71%
test-4: < oltp_update_index >
* QPS : 17530.75 ± 0.6709% (std=77.49) delta: -1.05% (p=0.498)
* AvgMs : 14.45 ± 0.7887% (std=0.07) delta: -0.10%
* PercentileMs99 : 31.60 ± 1.0823% (std=0.28) delta: 0.00%
test-5: < oltp_update_non_index >
* QPS : 29919.09 ± 0.2269% (std=45.56) delta: 0.22% (p=0.632)
* AvgMs : 8.55 ± 0.2572% (std=0.01) delta: -0.17%
* PercentileMs99 : 21.11 ± 0.0000% (std=0.00) delta: 0.00%
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cherry pick to release-3.0 in PR #12707 |
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cherry pick to release-3.1 in PR #12708 |
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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
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