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https://reviews.apache.org/r/39146/
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Review request for Ambari and Andrew Onischuk.
Bugs: AMBARI-13238
https://issues.apache.org/jira/browse/AMBARI-13238
Repository: ambari
Description
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The MySQL service check in mysql_service.py simply checks for a process with
name mysqld. In our environment, a different service ran another MySQL instance
on that node and as a result, the status of the MySQL service in Hive showed
green (because it could find a mysqld process) even though the instance used by
Hive wasn't started. That also made the "Start Service" action for Hive fail,
because the metastore service couldn't connect to the MySQL database.
The proposed fix makes the service check more robust by retrieving the pid_file
of the MySQL instance first by running "mysqladmin variables" and parsing out
the pid_file. Then it checks if the process exists.
As a side-note: the initial fix tried to get the pid_file from the /etc/my.cnf
file but I found that while this is one default location for the MySQL
configuration, there are other places where the file can be referenced. Since
the MySQL instance launched by Hive is not getting any parameters for config
file or pid_file, MySQL must read it from one of the default locations and
running "mysqladmin variables" must return the config values for the running
instance used by Hive. The other instance running needs to explicitely set
values for config file and pid because otherwise would collide with the default
instance.
Diffs
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ambari-server/src/main/resources/common-services/HIVE/0.12.0.2.0/package/scripts/mysql_service.py
c48c1ef
ambari-server/src/test/python/stacks/2.0.6/HIVE/test_mysql_server.py 1155e9f
Diff: https://reviews.apache.org/r/39146/diff/
Testing
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Updated UTs in test_mysql_server.py with new status command and ran them
successfully. Also manually tested in an installed cluster environment.
Thanks,
Thomas Friedrich
