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MY-012985 A long semaphore wait

acerolaacerola ContributorCurrent User Role Novice
After I upgraded from Percona 8.0.16-7 to 8.0.18-9, I started getting these warnings in the log. Also, performance is very poor. I run Centos 7. Any ideas?
2019-12-19T12:20:15.137744Z 0 [Warning] [MY-012985] [InnoDB] A long semaphore wait:
--Thread 139710936921856 has waited at dict0stats.cc line 1260 for 241 seconds the semaphore:
S-lock on RW-latch at 0x7efebf166da0 created in file buf0buf.cc line 785
a writer (thread id 139709589550848) has reserved it in mode  exclusive
number of readers 0, waiters flag 1, lock_word: 0
Last time read locked in file row0sel.cc line 4922
Last time write locked in file /mnt/workspace/percona-server-8.0-redhat-binary/label_exp/min-centos-7-x64/test/rpmbuild/BUILD/percona-server-8.0.18-9/percona-server-8.0.18-9/storage/innobase/row/row0upd.cc line 3047
2019-12-19T12:20:15.146845Z 0 [Warning] [MY-012985] [InnoDB] A long semaphore wait:
--Thread 139690600232704 has waited at row0sel.cc line 4922 for 241 seconds the semaphore:
S-lock on RW-latch at 0x7efebf166da0 created in file buf0buf.cc line 785
a writer (thread id 139709589550848) has reserved it in mode  exclusive
number of readers 0, waiters flag 1, lock_word: 0
Last time read locked in file row0sel.cc line 4922
Last time write locked in file /mnt/workspace/percona-server-8.0-redhat-binary/label_exp/min-centos-7-x64/test/rpmbuild/BUILD/percona-server-8.0.18-9/percona-server-8.0.18-9/storage/innobase/row/row0upd.cc line 3047
InnoDB: ###### Starts InnoDB Monitor for 30 secs to print diagnostic info:
InnoDB: Pending preads 0, pwrites 0

=====================================
2019-12-19 09:20:20 0x7f11ece1a700 INNODB MONITOR OUTPUT
=====================================

Comments

  • George LorchGeorge Lorch Percona Percona Moderator Role Patron
    We have not seen such behavior in our testing so far, but it is entirely possible that we are missing some specific case. There is always the possibility of a regression introduced either by us here at Percona or inherited from Oracle MySQL. Please report a bug at https://jira.percona.com/projects/PS with as much information that you can regarding your environment, schemas, data, queries, etc... and our support team will try to confirm the issue.

    --
    George O. Lorch III
    Director of Server Engineering - Percona Server
  • acerolaacerola Contributor Current User Role Novice
    I created the bug report: https://jira.percona.com/browse/PS-6756

    I noticed this in the log:
    2019-12-19T08:12:25.030516Z 0 [System] [MY-010910] [Server] /usr/sbin/mysqld: Shutdown complete (mysqld 8.0.16-7)  Percona Server (GPL), Release 7, Revision 613e312.
    2019-12-19T08:12:27.503856Z 0 [System] [MY-010116] [Server] /usr/sbin/mysqld (mysqld 8.0.18-9) starting as process 175120
    2019-12-19T08:12:38.587506Z 1 [System] [MY-011090] [Server] Data dictionary upgrading from version '80016' to '80017'.
    2019-12-19T08:12:39.402430Z 1 [System] [MY-013413] [Server] Data dictionary upgrade from version '80016' to '80017' completed.
    2019-12-19T08:12:44.208245Z 4 [System] [MY-013381] [Server] Server upgrade from '80016' to '80018' started.
    2019-12-19T08:12:49.309843Z 4 [System] [MY-013381] [Server] Server upgrade from '80016' to '80018' completed.
    

    The data dictionary upgraded from 80016 to 80017, and not to 80018. Is this normal?
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