XAManagedConnectionFactory.isEqual(Object) deadlock in JBoss EAP

Issue

• Deadlock found in thread dump for threads executing org.jboss.jca.adapters.jdbc.xa.XAManagedConnectionFactory.isEqual(Object)

• Two or more threads hold one lock on an instance of java.util.Collections$SynchronizedMap and attempt to obtain a lock on a different instance (e.g. locks on 0xaaaaaaa and 0xbbbbbbb in the example below).

  "thread-one" ...
  java.lang.Thread.State: BLOCKED (on object monitor)
      at java.util.Collections$SynchronizedMap.get(Collections.java:2584)
      - waiting to lock <0xaaaaaaa> (a java.util.Collections$SynchronizedMap)
      at java.util.AbstractMap.equals(AbstractMap.java:495)
      at java.util.Collections$SynchronizedMap.equals(Collections.java:2631)
      - locked <0xbbbbbbb> (a java.util.Collections$SynchronizedMap)
      at org.jboss.jca.adapters.jdbc.xa.XAManagedConnectionFactory.isEqual(XAManagedConnectionFactory.java:563)
      - locked <0xbbbbbbb> (a java.util.Collections$SynchronizedMap)
      at org.jboss.jca.adapters.jdbc.xa.XAManagedConnectionFactory.equals(XAManagedConnectionFactory.java:598)
      at org.jboss.jca.adapters.jdbc.BaseWrapperManagedConnectionFactory$SubjectActions.doCheck(BaseWrapperManagedConnectionFactory.java:1397)
      at org.jboss.jca.adapters.jdbc.BaseWrapperManagedConnectionFactory$SubjectActions.addMatchingProperties(BaseWrapperManagedConnectionFactory.java:1508)
      at org.jboss.jca.adapters.jdbc.BaseWrapperManagedConnectionFactory.getConnectionProperties(BaseWrapperManagedConnectionFactory.java:1135)
      at org.jboss.jca.adapters.jdbc.xa.XAManagedConnectionFactory.matchManagedConnections(XAManagedConnectionFactory.java:533)
      ...
      at org.jboss.jca.adapters.jdbc.WrapperDataSource.getConnection(WrapperDataSource.java:138)
      at org.jboss.as.connector.subsystems.datasources.WildFlyDataSource.getConnection(WildFlyDataSource.java:66)
      ...
  
  "thread-two" ...
  java.lang.Thread.State: BLOCKED (on object monitor)
      at java.util.Collections$SynchronizedMap.size(Collections.java:2572)
      - waiting to lock <0xbbbbbbb> (a java.util.Collections$SynchronizedMap)
      at java.util.AbstractMap.equals(AbstractMap.java:482)
      at java.util.Collections$SynchronizedMap.equals(Collections.java:2631)
      - locked <0xaaaaaaa> (a java.util.Collections$SynchronizedMap)
      at org.jboss.jca.adapters.jdbc.xa.XAManagedConnectionFactory.isEqual(XAManagedConnectionFactory.java:563)
      - locked <0xaaaaaaa> (a java.util.Collections$SynchronizedMap)
      at org.jboss.jca.adapters.jdbc.xa.XAManagedConnectionFactory.equals(XAManagedConnectionFactory.java:598)
      ... [same stack as thread-one above] ...
      at org.jboss.jca.adapters.jdbc.WrapperDataSource.getConnection(WrapperDataSource.java:138)
      at org.jboss.as.connector.subsystems.datasources.WildFlyDataSource.getConnection(WildFlyDataSource.java:66)
      ...