Apparent Deadlock error messages in Crowd
Platform Notice: Data Center Only - This article only applies to Atlassian products on the Data Center platform.
Note that this KB was created for the Data Center version of the product. Data Center KBs for non-Data-Center-specific features may also work for Server versions of the product, however they have not been tested. Support for Server* products ended on February 15th 2024. If you are running a Server product, you can visit the Atlassian Server end of support announcement to review your migration options.
*Except Fisheye and Crucible
Summary
The following message appears frequently in theatlassian-crowd.log.
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C3P0PooledConnectionPoolManager[identityToken->2so7snad10br9smlhh0jq|7dd5f43f]-AdminTaskTimer WARN [mchange.v2.async.ThreadPoolAsynchronousRunner] com.mchange.v2.async.ThreadPoolAsynchronousRunner$DeadlockDetector@4e9df9d2 -- APPARENT DEADLOCK!!! Complete Status:
Managed Threads: 3
Active Threads: 3
Active Tasks:
com.mchange.v2.resourcepool.BasicResourcePool$AsyncTestIdleResourceTask@1203adc7
on thread: C3P0PooledConnectionPoolManager[identityToken->2so7snad10br9smlhh0jq|7dd5f43f]-HelperThread-#2
com.mchange.v2.resourcepool.BasicResourcePool$AsyncTestIdleResourceTask@1e5bb8f7
on thread: C3P0PooledConnectionPoolManager[identityToken->2so7snad10br9smlhh0jq|7dd5f43f]-HelperThread-#1
com.mchange.v2.resourcepool.BasicResourcePool$AsyncTestIdleResourceTask@4dc74be2
on thread: C3P0PooledConnectionPoolManager[identityToken->2so7snad10br9smlhh0jq|7dd5f43f]-HelperThread-#0This may cause performance issues with Crowd or users may not be able to authenticate to connected applications during these times.
Environment
Crowd Server or Data Center
Any connected database
Cause
This error can indicate issues with the database, its connection pool, and/or the database's ability to cleanly acquire a new connection.
Resolution
⚠️ Restart of Crowd is required after making any of the below changes
Optimize the database connection pool. This defines the maximum number of connections in the database pool. This number should be at least 10 counts higher or 25% higher (whichever value is greater) than the number of HTTP threads (defined under
<Crowd_Install_Directory>/apache-tomcat/conf/server.xmlfile using parametermaxThreads). This is to account for connections used for background jobs on top of active HTTP threads.To set the database connection pool:
If you are using a direct JDBC connection to the database:
Navigate to the <Crowd_Home_Directory>/crowd.cfg.xml and you will find the following property which should be updated as per your need:
1<property name="hibernate.c3p0.max_size">30</property>If you are using a data source to connect to the database in
<Crowd_Install_Directory>/apache-tomcat/conf/server.xml, configure themaxTotalparameter
Also confirm if a validation query exists to check for broken connections and clean them from the availability pool. This is under:
<Crowd_Home_Directory>/crowd.cfg.xmlfile, and check if the following property exists, and if not add them manually:For PostgreSQL, MSSQL, MySQL:
1<property name="hibernate.c3p0.preferredTestQuery">select 1</property>For Oracle:
1<property name="hibernate.c3p0.preferredTestQuery">select 1 from dual</property>
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