Database deadlocks when accessing projects

2016-03-16 06:59:37,256 ERROR [qtp1768952842-308 ] fisheye SessionState-commitAllTx - Commit failed. Rolling back.
org.hibernate.exception.LockAcquisitionException: could not execute statement
        at org.hibernate.dialect.PostgreSQL81Dialect$2.convert(PostgreSQL81Dialect.java:388) [hibernate-core-4.2.13.Final.jar:4.2.13.Final]
        at org.hibernate.exception.internal.StandardSQLExceptionConverter.convert(StandardSQLExceptionConverter.java:49) [hibernate-core-4.2.13.Final.jar:4.2.13.Final]
        at org.hibernate.engine.jdbc.spi.SqlExceptionHelper.convert(SqlExceptionHelper.java:124) [hibernate-core-4.2.13.Final.jar:4.2.13.Final]
        at org.hibernate.engine.jdbc.spi.SqlExceptionHelper.convert(SqlExceptionHelper.java:109) [hibernate-core-4.2.13.Final.jar:4.2.13.Final]
        at org.hibernate.engine.jdbc.internal.ResultSetReturnImpl.executeUpdate(ResultSetReturnImpl.java:189) [hibernate-core-4.2.13.Final.jar:4.2.13.Final]
        at org.hibernate.engine.jdbc.batch.internal.NonBatchingBatch.addToBatch(NonBatchingBatch.java:58) [hibernate-core-4.2.13.Final.jar:4.2.13.Final]
        at org.hibernate.persister.collection.AbstractCollectionPersister.remove(AbstractCollectionPersister.java:1157) [hibernate-core-4.2.13.Final.jar:4.2.13.Final]
        at org.hibernate.action.internal.CollectionRemoveAction.execute(CollectionRemoveAction.java:111) [hibernate-core-4.2.13.Final.jar:4.2.13.Final]
        at org.hibernate.engine.spi.ActionQueue.execute(ActionQueue.java:395) [hibernate-core-4.2.13.Final.jar:4.2.13.Final]
        at org.hibernate.engine.spi.ActionQueue.executeActions(ActionQueue.java:387) [hibernate-core-4.2.13.Final.jar:4.2.13.Final]
        at org.hibernate.engine.spi.ActionQueue.executeActions(ActionQueue.java:307) [hibernate-core-4.2.13.Final.jar:4.2.13.Final]
        at org.hibernate.event.internal.AbstractFlushingEventListener.performExecutions(AbstractFlushingEventListener.java:349) [hibernate-core-4.2.13.Final.jar:4.2.13.Final]
        at org.hibernate.event.internal.DefaultFlushEventListener.onFlush(DefaultFlushEventListener.java:56) [hibernate-core-4.2.13.Final.jar:4.2.13.Final]
        at org.hibernate.internal.SessionImpl.flush(SessionImpl.java:1159) [hibernate-core-4.2.13.Final.jar:4.2.13.Final]
        at org.hibernate.internal.SessionImpl.managedFlush(SessionImpl.java:404) [hibernate-core-4.2.13.Final.jar:4.2.13.Final]
        at org.hibernate.engine.transaction.internal.jdbc.JdbcTransaction.beforeTransactionCommit(JdbcTransaction.java:101) [hibernate-core-4.2.13.Final.jar:4.2.13.Final]
        at org.hibernate.engine.transaction.spi.AbstractTransactionImpl.commit(AbstractTransactionImpl.java:175) [hibernate-core-4.2.13.Final.jar:4.2.13.Final]
        at com.cenqua.crucible.hibernate.SessionState.commit(SessionState.java:165) [fisheye.jar:?]
        at com.cenqua.crucible.hibernate.SessionState.commitAllTx(SessionState.java:118) [fisheye.jar:?]
        at com.cenqua.crucible.hibernate.SessionState.commitTx(SessionState.java:109) [fisheye.jar:?]
        at com.cenqua.crucible.hibernate.HibernateUtil.commitTransaction(HibernateUtil.java:385) [fisheye.jar:?]
...
Caused by: org.postgresql.util.PSQLException: ERROR: deadlock detected
      Detail: Process 94047 waits for ShareLock on transaction 177190; blocked by process 95026.
    Process 95026 waits for ShareLock on transaction 177191; blocked by process 94047.
      Hint: See server log for query details.