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executor: make the ParallelApply be safe to be called again after returning empty results #24935

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merged 2 commits into from
Jun 1, 2021
Merged

executor: make the ParallelApply be safe to be called again after returning empty results #24935

merged 2 commits into from
Jun 1, 2021

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qw4990
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@qw4990 qw4990 commented May 27, 2021 •
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What problem does this PR solve?

Issue Number: close #24930

Problem Summary: executor: make the ParallelApply be safe to be called again after returning empty results

What is changed and how it works?

When ParallelApply is under TopN, it may be called again after returning empty results and then it will hang forever.
This PR make the ParallelApply be safe to be called again after returning empty results

Please see #24930 for more details.

Check List

Tests

  • Unit test

Release note

  • executor: make the ParallelApply be safe to be called again after returning empty results

@qw4990 qw4990 added type/bugfix This PR fixes a bug. sig/execution SIG execution labels May 27, 2021
@qw4990 qw4990 requested review from XuHuaiyu, wshwsh12 and lzmhhh123 May 27, 2021 11:22
@qw4990 qw4990 requested a review from a team as a code owner May 27, 2021 11:22
@ti-chi-bot ti-chi-bot added the size/S Denotes a PR that changes 10-29 lines, ignoring generated files. label May 27, 2021
@ichn-hu ichn-hu mentioned this pull request May 27, 2021
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/lgtm

@ti-chi-bot ti-chi-bot added the status/LGT1 Indicates that a PR has LGTM 1. label May 28, 2021
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Will this issue be reproduced when using non-parallel apply ?

@qw4990
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qw4990 commented May 31, 2021

Will this issue be reproduced when using non-parallel apply ?

No, non-parallel apply is safe in this case.

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qw4990 commented May 31, 2021

PTAL @wshwsh12 @lzmhhh123

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XuHuaiyu commented Jun 1, 2021

/lgtm

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@XuHuaiyu: Please use GitHub review feature instead of /lgtm [cancel] when you want to submit review to the pull request.
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[REVIEW NOTIFICATION]

This pull request has been approved by:

  • XuHuaiyu
  • wshwsh12

To complete the pull request process, please ask the reviewers in the list to review by filling /cc @reviewer in the comment.
After your PR has acquired the required number of LGTMs, you can assign this pull request to the committer in the list by filling /assign @committer in the comment to help you merge this pull request.

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@ti-chi-bot ti-chi-bot added status/LGT2 Indicates that a PR has LGTM 2. and removed status/LGT1 Indicates that a PR has LGTM 1. labels Jun 1, 2021
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wshwsh12 commented Jun 1, 2021

/merge

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This pull request has been accepted and is ready to merge.

Commit hash: 493407e

@ti-chi-bot ti-chi-bot added the status/can-merge Indicates a PR has been approved by a committer. label Jun 1, 2021
@ti-chi-bot ti-chi-bot merged commit 48e25cd into pingcap:master Jun 1, 2021
ti-srebot pushed a commit to ti-srebot/tidb that referenced this pull request Jun 1, 2021
@qw4990 @ti-srebot
cherry pick pingcap#24935 to release-5.0
2308e70 
Signed-off-by: ti-srebot <ti-srebot@pingcap.com>
@ti-srebot ti-srebot mentioned this pull request Jun 1, 2021
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cherry pick to release-5.0 in PR #25011

ti-chi-bot pushed a commit that referenced this pull request Jun 22, 2021
@ti-srebot
executor: make the ParallelApply be safe to be called again after ret…
ef3e4fd 
…urning empty results (#24935) (#25011)
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@wshwsh12 wshwsh12 wshwsh12 approved these changes

@XuHuaiyu XuHuaiyu Awaiting requested review from XuHuaiyu

@lzmhhh123 lzmhhh123 Awaiting requested review from lzmhhh123

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needs-cherry-pick-release-5.0 sig/execution SIG execution size/S Denotes a PR that changes 10-29 lines, ignoring generated files. status/can-merge Indicates a PR has been approved by a committer. status/LGT2 Indicates that a PR has LGTM 2. type/bugfix This PR fixes a bug.
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Successfully merging this pull request may close these issues.

a query may hang forever when its plan has a ParallelApply under TopN
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@qw4990 @XuHuaiyu @ti-chi-bot @wshwsh12 @ti-srebot