Details
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Task
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Status: Closed (View Workflow)
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Critical
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Resolution: Fixed
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None
Description
On a replication slave that has parallel replication enabled, if slave_parallel_max_queued is set too small, then the SQL thread's queue can sometimes be too small to assign work to all of the slave worker threads. When this happens, the SQL thread's state will be "Waiting for room in worker thread event", and the idle worker thread's state will be "Waiting for work from SQL thread".
| 4 | system user | | NULL | Connect | 139 | Waiting for work from SQL thread | NULL | 0.000 |
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| 21 | system user | | NULL | Connect | 45 | Waiting for room in worker thread event queue | NULL | 0.000 |
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I think it would be useful to add a status variable that gets incremented if slave's parallel worker thread is idle because the SQL thread's queue is full.
Attachments
Activity
Hello serg
Since fix version is 10.6, ported my 10.5 changes to 10.6 and tested them.
Please find the 10.6 patch: https://github.com/MariaDB/server/commit/1d5f0db0158c5a4c2e82abd3b881de46a719412d
Test results: http://buildbot.askmonty.org/buildbot/grid?category=main&branch=bb-10.6-sujatha
This patch is for 'replication_applier_status_by_worker' table alone.
Rest of the tables are implemented as part of MDEV-16437.
Current patch will be used as base of MDEV-16437 and each PFS table specific change will be added as a separate commit.
Thank you.
Hello serg
Can you please review the changes for MDEV-20220.
Patch: https://github.com/MariaDB/server/commit/0922edb1b162c5aa73c11867157e0e118f79bbc6
Test results: http://buildbot.askmonty.org/buildbot/grid?category=main&branch=bb-10.5-sujatha
Hello serg, GeoffMontee and Elkin
As part of current task can we add a new `performance schema` table similar to upstream?
The table can capture following details. It can be extended further to include few more details.
performance_schema.replication_applier_status_by_worker
| Column Name | Value |
|---|---|
| THREAD_ID | None |
| SERVICE_STATE | None |
| LAST_SEEN_TRANSACTION | None |
| LAST_ERROR_NUMBER | Last_SQL_Errno |
| LAST_ERROR_MESSAGE | Last_SQL_Error |
| LAST_ERROR_TIMESTAMP | Last_SQL_Error_Timestamp |
| WORKER_IDLE_TIME | Total idle time by worker "Waiting for work from SQL thread" |
| LAST_TRANS_WAIT_FOR_COMMIT_ORDER | Total waiting time spent by current transaction to reach its turn for commit |
| LAST_TRANS_RETRY_COUNT | Total number retries attempted by last transaction |
Hello Sergei,
Good Morning.
I have addressed your review comments. Please review the new set of changes.
Patch: https://github.com/MariaDB/server/commit/9abbb589e6d6f61e03cad0fc5c5aee31077dd00c
BuildBot Results: http://buildbot.askmonty.org/buildbot/grid?category=main&branch=bb-10.6-sujatha
Thank you.