| Bug #76766 | innodb: manual could explain how to let page cleaner threads change priority | ||
|---|---|---|---|
| Submitted: | 21 Apr 2015 9:02 | Modified: | 29 Apr 2015 14:55 |
| Reporter: | Shane Bester (Platinum Quality Contributor) | Email Updates: | |
| Status: | Closed | Impact on me: | |
| Category: | MySQL Server: Documentation | Severity: | S4 (Feature request) |
| Version: | 5.7.7 | OS: | Any |
| Assigned to: | CPU Architecture: | Any | |
[21 Apr 2015 9:02]
Shane Bester
[29 Apr 2015 14:55]
Daniel Price
Posted by developer: The code was implemented for Linux only (WL7868). #ifdef UNIV_LINUX /* linux might be able to set different setting for each thread. worth to try to set high priority for page cleaner threads */ if (buf_flush_page_cleaner_set_priority( buf_flush_page_cleaner_priority)) { ib::info() << "page_cleaner coordinator priority: " << buf_flush_page_cleaner_priority; } else { ib::info() << "If the mysqld execution user is authorized," " page cleaner thread priority can be changed." " See the man page of setpriority()."; } #endif /* UNIV_LINUX */ " To authorize the mysqld execution user, you can modify /etc/security/limits.conf (http://linux.die.net/man/5/limits.conf) to allow the mysql user to go beyond 0. For example, if the mysql user is the mysqld execution user, you might add the following lines to /etc/security/limits.conf. mysql hard nice -20 mysql soft nice -20 Documentation updates: (1) The MySQL 5.7.6 release notes entry for WL7868 has been revised. (2) Information was added to the innodb_page_cleaners description: https://dev.mysql.com/doc/refman/5.7/en/innodb-parameters.html#sysvar_innodb_page_cleaners Updates should appear online within 24 hours.
[14 Dec 2015 11:03]
Simon Mudd
Is it possible to re-open this? The documentation may have been updated but the underlying issue (the mysqld logging) has not changed. 2015-12-14T10:33:09.755472Z 0 [Note] /usr/sbin/mysqld (mysqld 5.7.10-log) starting as process 44524 ... ... 2015-12-14T10:33:16.403031Z 0 [Note] InnoDB: If the mysqld execution user is authorized, page cleaner thread priority can be changed. See the man page of setpriority(). I think what is needed really is to change the log message: (1) The "if" statement seems confusing. Is there a problem or isn't there? - if you are able to change the priority or it's been changed then indicate that. Looking at the code shown above it seems that this is logged if the priority changes. - if you were not able to make such a change then indicate it differently. (2) point to how to do that. This bug report does not clearly indicate what configuration change is needed and the relevant documentation has been updated. So please refer to it in the error message so that we can find it immediately. I'd expect the logging to be slightly different, something along the lines of: 2015-12-14T10:33:16.403031Z 0 [Note] InnoDB: Page cleaner thread priority unchanged. See https://dev.mysql.com/doc/refman/5.7/en/innodb-parameters.html#sysvar_innodb_page_cleaners on how to configure this if required. Thanks.
[22 Jan 2016 12:11]
Andrii Nikitin
Posted by developer: Simon, (1) will be addressed in new bug #80115 (2) is not actually scope of MySQL and may really differ for some Linux distributions. As mentioned in MySQL manual "Refer to your Linux operating system documentation for more information"
[25 Jan 2016 8:46]
Simon Mudd
Thanks. Subscribed now to bug#80115. That said "it's not in the scope of MySQL...". Well there may be different ways to solve the problem, but if you are reporting a problem and expect/want the DBA to fix it then at least the explanation of the problem and some sort of documentation on how to solve it is needed. It is true that you can not cover all operating system/distributions, but it would be helpful to provide information on those platforms that are supported by Oracle such as RHEL/OEL, etc... I am sure that will be suitable addressed.
