Scheduler no throw in destruction and avoid updated min-tso query hang #4367
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Signed-off-by: fzhedu <fzhedu@gmail.com>
| @@ -87,42 +87,29 @@ void MinTSOScheduler::deleteCancelledQuery(const UInt64 tso, MPPTaskManager & ta | |||
| waiting_set.erase(tso); | |||
| GET_METRIC(tiflash_task_scheduler, type_waiting_queries_count).Set(waiting_set.size()); | |||
| GET_METRIC(tiflash_task_scheduler, type_active_queries_count).Set(active_set.size()); | |||
| LOG_FMT_DEBUG(log, "{} query {} (is min = {}) is deleted from active set {} left {} or waiting set {} left {}.", is_cancelled ? "Cancelled" : "Finished", tso, tso == min_tso, active_set.find(tso) != active_set.end(), active_set.size(), waiting_set.find(tso) != waiting_set.end(), waiting_set.size()); | |||
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I think both active_set.find(tso) != active_set.end() and waiting_set.find(tso) != waiting_set.end() will return false because you already erase them in L86-L87
| /// NOTE: if the cancelled query hang, it will block the min_tso, possibly resulting in deadlock. so here force scheduling waiting tasks of the updated min_tso query. | ||
| if (updateMinTSO(tso, true, "when cancelling it.")) | ||
| /// NOTE: if updated min_tso query has waiting tasks, they should be scheduled, especially when the soft-limited threads are amost used and active tasks are in resources deadlock which cannot release threads soon. | ||
| if (updateMinTSO(tso, true, is_cancelled ? "when cancelling it" : "as deleting it")) |
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as deleting it => as finish it?
| if (isWaiting) | ||
| { | ||
| /// cancel this task, then TiDB will finally notify this tiflash node canceling all tasks of this tso and update metrics. | ||
| task->cancel(msg); |
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will cancel triger OPs of waiting_set again?
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yes, conduct the cancel processing.
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since cancel will also triger OPs of waiting_set, will L197 waiting_set.erase(tso) be a duplicated op?
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as it comments: /// avoid the left waiting tasks of this query reaching here many times.
Signed-off-by: fzhedu <fzhedu@gmail.com>
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/run-all-tests |
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Signed-off-by: fzhedu <fzhedu@gmail.com>
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terminated as expected. |
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dbms/src/Flash/Mpp/MPPTask.cpp
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| { | ||
| std::unique_lock lock(schedule_mu); | ||
| schedule_cv.wait(lock, [&] { return schedule_state != ScheduleState::WAITING; }); | ||
| time_cost = stopwatch.elapsedSeconds(); | ||
| GET_METRIC(tiflash_task_scheduler_waiting_duration_seconds).Observe(time_cost); | ||
| if (schedule_state == ScheduleState::FAILED) |
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I would like to distinguish the cases that task is failed to schedule due to resource exhausted or due to the related query is cancelled.
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ok, I will add a enum flagh: EXCEEDED
Signed-off-by: fzhedu <fzhedu@gmail.com>
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/run-all-tests |
| if (schedule_state == ScheduleState::EXCEEDED) | ||
| { | ||
| throw Exception("{} is failed to schedule because of exceeding the thread hard limit in min-tso scheduler.", id.toString()); | ||
| } |
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Why not throw error if the schedule state is FAILED?
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the later processing in MppTask->runImp() will throw because this query is to be cancelled, whose state is not RUNNING..
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But after the task is scheduled with FAILED schedule state, two threads are running concurrently with
- runImpl thread begin to run
- cancel thread mark MPPTask as cancelled
There is no guarantee that rumImpl thread will see theCancelledstatus right after it is waked up.
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updated to this goal.
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Signed-off-by: fzhedu <fzhedu@gmail.com>
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/run-all-tests |
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This pull request has been accepted and is ready to merge. Commit hash: 3e563cc
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@fzhedu: Your PR was out of date, I have automatically updated it for you. At the same time I will also trigger all tests for you: /run-all-tests If the CI test fails, you just re-trigger the test that failed and the bot will merge the PR for you after the CI passes. Instructions for interacting with me using PR comments are available here. If you have questions or suggestions related to my behavior, please file an issue against the ti-community-infra/tichi repository. |
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In response to a cherrypick label: new pull request created: #4399. |
Signed-off-by: fzhedu fzhedu@gmail.com
What problem does this PR solve?
Issue Number: close #4366
Problem Summary:
What is changed and how it works?
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