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view doc/mysql.txt @ 6565:2c2dbfc332ba
Try to handle multiple connections better.
The session database is a hot spot. When multiple requests (e.g. 20)
come in at the same time session database contention can get great.
The original code didn't retry session database access when the open
failed. This resulted in errors at the client.
The second pass delayed 0.01 seconds and retried. It was better but we
still had multiple second stalls. I think the first request got in,
everybody else backed up and then retried at the same time. Again they
stepped on each other. With logging I would see many counters go all
the way to low single digits or to -1 indicating falure.
This pass uses randomint to generate delays from 0-.125 seconds in 5ms
increments. This performs better in testing. I rarely saw a counter
less than 13 (2 failed retries). Current logging starts after 6
failures and counts down until success or failure.
| author | John Rouillard <rouilj@ieee.org> |
|---|---|
| date | Thu, 16 Dec 2021 20:02:00 -0500 |
| parents | 81ae33038ec5 |
| children | fc9e16fe3991 |
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.. index:: mysql; deployment notes ============= MySQL Backend ============= This notes detail the MySQL backend for the Roundup issue tracker. Prerequisites ============= To use MySQL as the backend for storing roundup data, you also need to install: 1. MySQL RDBMS 4.0.18 or higher - https://www.mysql.com/. Your MySQL installation MUST support InnoDB tables (or Berkeley DB (BDB) tables if you have no other choice). If you're running < 4.0.18 (but not <4.0) then you'll need to use BDB to pass all unit tests. Edit the ``roundup/backends/back_mysql.py`` file to enable DBD instead of InnoDB. 2. Python MySQL interface - https://pypi.org/project/mysqlclient/ Other Configuration =================== If you are indexing large documents (e.g attached file contents) using MySQL, you may need to increase the max_allowed_packet size. If you don't you can see the error:: 'MySql Server has gone away (2006)' To do this edit /etc/my.conf and change:: [mysqld] max_allowed_packet = 1M the 'max_allowed_packet' value from '1M' to '64M' or larger. Alternatively you can install an alternate indexer (whoosh, xapian etc.) and force the tracker to use it by setting the ``indexer`` setting in the tracker's ``config.ini``. This fix was supplied by telsch. See issue https://issues.roundup-tracker.org/issue2550743 for further info or if you are interested in developing a patch to roundup to help work around this issue. Running the MySQL tests ======================= Roundup tests expect an empty MySQL database. Two alternate ways to provide this: 1. If you have root permissions on the MySQL server, you can create the necessary database entries using the follwing SQL sequence. Use ``mysql`` on the command line to enter:: CREATE DATABASE rounduptest; USE rounduptest; GRANT ALL PRIVILEGES ON rounduptest.* TO rounduptest@localhost IDENTIFIED BY 'rounduptest'; FLUSH PRIVILEGES; 2. If your administrator has provided you with database connection info, see the config values in 'test/db_test_base.py' about which database connection, name and user will be used. The MySQL database should not contain any tables. Tests will not drop the database with existing data. Showing MySQL who's boss ======================== If things ever get to the point where that test database is totally hosed, just:: $ su - # /etc/init.d/mysql stop # rm -rf /var/lib/mysql/rounduptest # /etc/init.d/mysql start and all will be better (note that on some systems, ``mysql`` is spelt ``mysqld``).