Percona Server moved to https://jira.percona.com/projects/PS

Log tracking should not acquire log mutex for log reading

Bug #1171699 reported by Laurynas Biveinis
6
This bug affects 1 person
Affects Status Importance Assigned to Milestone
Percona Server moved to https://jira.percona.com/projects/PS
Fix Released
Medium
Laurynas Biveinis
Percona Server moved to https://jira.percona.com/projects/PS 5.6.11-60.3
5.1
Fix Released
Medium
Laurynas Biveinis
Percona Server moved to https://jira.percona.com/projects/PS 5.1.69-14.7
5.5
Fix Released
Medium
Laurynas Biveinis
Percona Server moved to https://jira.percona.com/projects/PS 5.5.32-31.0
5.6
Fix Released
Medium
Laurynas Biveinis
Percona Server moved to https://jira.percona.com/projects/PS 5.6.11-60.3

Bug Description

The log tracker thread reads the log in log block size chunks by doing

 mutex_enter(&log_sys->mutex);
 log_group_read_log_seg(LOG_RECOVER, log_bmp_sys->read_buf,
          group, block_start_lsn, block_end_lsn);
 mutex_exit(&log_sys->mutex);

This code allows reusing log_group_read_log_seg(), which requires that log_sys mutex is being held, without any changes, but there is no reason to hold the mutex for the I/O itself.

Tags: bitmap xtradb

Related branches

lp:~laurynas-biveinis/percona-server/bmp-fixes-5.5
Stewart Smith (community): Approve
Diff: 1312 lines (+537/-143) (has conflicts)
19 files modified
Percona-Server/mysql-test/suite/innodb/r/percona_changed_page_bmp.result (+7/-0)
Percona-Server/mysql-test/suite/innodb/r/percona_changed_pages.result (+58/-33)
Percona-Server/mysql-test/suite/innodb/r/percona_changed_pages_empty.result (+1/-0)
Percona-Server/mysql-test/suite/innodb/t/percona_changed_page_bmp.test (+33/-0)
Percona-Server/mysql-test/suite/innodb/t/percona_changed_page_bmp_flush.test (+2/-2)
Percona-Server/mysql-test/suite/innodb/t/percona_changed_pages.test (+99/-28)
Percona-Server/mysql-test/suite/innodb/t/percona_changed_pages_empty.test (+4/-2)
Percona-Server/mysql-test/suite/sys_vars/r/all_vars.result (+0/-2)
Percona-Server/mysql-test/suite/sys_vars/r/innodb_max_changed_pages_basic.result (+78/-0)
Percona-Server/mysql-test/suite/sys_vars/t/innodb_max_changed_pages_basic.test (+60/-0)
Percona-Server/storage/innobase/handler/i_s.cc (+8/-6)
Percona-Server/storage/innobase/include/log0log.h (+3/-1)
Percona-Server/storage/innobase/include/log0online.h (+2/-0)
Percona-Server/storage/innobase/include/os0file.h (+4/-2)
Percona-Server/storage/innobase/log/log0log.c (+13/-3)
Percona-Server/storage/innobase/log/log0online.c (+161/-53)
Percona-Server/storage/innobase/log/log0recv.c (+4/-3)
Percona-Server/storage/innobase/os/os0file.c (+0/-2)
Percona-Server/storage/innobase/srv/srv0start.c (+0/-6)
lp:~laurynas-biveinis/percona-server/bmp-fixes-5.6
Stewart Smith (community): Approve
Diff: 1321 lines (+545/-145)
18 files modified
Percona-Server/mysql-test/suite/innodb/r/percona_changed_page_bmp.result (+8/-1)
Percona-Server/mysql-test/suite/innodb/r/percona_changed_pages.result (+59/-33)
Percona-Server/mysql-test/suite/innodb/r/percona_changed_pages_empty.result (+1/-0)
Percona-Server/mysql-test/suite/innodb/t/percona_changed_page_bmp.test (+34/-4)
Percona-Server/mysql-test/suite/innodb/t/percona_changed_page_bmp_flush.test (+2/-2)
Percona-Server/mysql-test/suite/innodb/t/percona_changed_pages.test (+100/-28)
Percona-Server/mysql-test/suite/innodb/t/percona_changed_pages_empty.test (+4/-2)
Percona-Server/mysql-test/suite/sys_vars/r/all_vars.result (+0/-2)
Percona-Server/mysql-test/suite/sys_vars/r/innodb_max_changed_pages_basic.result (+78/-0)
Percona-Server/mysql-test/suite/sys_vars/t/innodb_max_changed_pages_basic.test (+60/-0)
Percona-Server/storage/innobase/handler/i_s.cc (+8/-6)
Percona-Server/storage/innobase/include/log0log.h (+3/-1)
Percona-Server/storage/innobase/include/log0online.h (+2/-0)
Percona-Server/storage/innobase/include/os0file.h (+4/-2)
Percona-Server/storage/innobase/log/log0log.cc (+13/-3)
Percona-Server/storage/innobase/log/log0online.cc (+165/-56)
Percona-Server/storage/innobase/log/log0recv.cc (+4/-3)
Percona-Server/storage/innobase/os/os0file.cc (+0/-2)
lp:~laurynas-biveinis/percona-server/bmp-fixes-5.1
Stewart Smith (community): Approve
Diff: 1153 lines (+400/-142) (has conflicts)
16 files modified
Percona-Server/mysql-test/suite/innodb_plugin/r/percona_changed_page_bmp.result (+7/-0)
Percona-Server/mysql-test/suite/innodb_plugin/r/percona_changed_pages.result (+58/-33)
Percona-Server/mysql-test/suite/innodb_plugin/r/percona_changed_pages_empty.result (+1/-0)
Percona-Server/mysql-test/suite/innodb_plugin/t/percona_changed_page_bmp.test (+33/-0)
Percona-Server/mysql-test/suite/innodb_plugin/t/percona_changed_page_bmp_flush.test (+2/-2)
Percona-Server/mysql-test/suite/innodb_plugin/t/percona_changed_pages.test (+99/-28)
Percona-Server/mysql-test/suite/innodb_plugin/t/percona_changed_pages_empty.test (+4/-2)
Percona-Server/storage/innodb_plugin/handler/i_s.cc (+8/-6)
Percona-Server/storage/innodb_plugin/include/log0log.h (+3/-1)
Percona-Server/storage/innodb_plugin/include/log0online.h (+2/-0)
Percona-Server/storage/innodb_plugin/include/os0file.h (+4/-2)
Percona-Server/storage/innodb_plugin/log/log0log.c (+13/-3)
Percona-Server/storage/innodb_plugin/log/log0online.c (+162/-54)
Percona-Server/storage/innodb_plugin/log/log0recv.c (+4/-3)
Percona-Server/storage/innodb_plugin/os/os0file.c (+0/-2)
Percona-Server/storage/innodb_plugin/srv/srv0start.c (+0/-6)
Laurynas Biveinis (laurynas-biveinis)
tags: added: xtradb
Revision history for this message
Laurynas Biveinis (laurynas-biveinis) wrote :

A preliminary fix that does not hold the mutex during the log read fixes a performance regression of some 30% on a Sysbench write-only workload and makes its performance ~match the case of log tracking disabled.

This fix still acquires the mutex for the log_group_calc_lsn_offset() call, which does not seem necessary neither, but removing that seems to be 1) more involved; 2) not that urgent now.

Laurynas Biveinis (laurynas-biveinis)
tags: added: bitmap
Revision history for this message
Shahriyar Rzayev (rzayev-sehriyar) wrote :

Percona now uses JIRA for bug reports so this bug report is migrated to: https://jira.percona.com/browse/PS-1356

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