Idle in TX / Java process hang's in the vicinity of JDBC

We've got an issue where an ETL process just sort of stalled on us last night.

It left a dreaded "Idle in Transaction" in the database. Although fortunatly
it didn't appear to have any tables locked.

No errors logged in the postgresql logfile.

(we're on JDBC driver v8.3-603)

We got a stack trace of the ETL process:
Name: Thread-957
State: RUNNABLE
Total blocked: 0 Total waited: 0

Stack trace:
java.net.SocketInputStream.socketRead0(Native Method)
java.net.SocketInputStream.read(SocketInputStream.java:129)
org.postgresql.core.VisibleBufferedInputStream.readMore(VisibleBufferedInputStream.java:135)
org.postgresql.core.VisibleBufferedInputStream.ensureBytes(VisibleBufferedInputStream.java:104)
org.postgresql.core.VisibleBufferedInputStream.read(VisibleBufferedInputStream.java:186)
org.postgresql.core.PGStream.Receive(PGStream.java:445)
org.postgresql.core.PGStream.ReceiveTupleV3(PGStream.java:350)
org.postgresql.core.v3.QueryExecutorImpl.processResults(QueryExecutorImpl.java:1306)
org.postgresql.core.v3.QueryExecutorImpl.execute(QueryExecutorImpl.java:192)
- locked org(dot)postgresql(dot)core(dot)v3(dot)QueryExecutorImpl(at)18493c9
org.postgresql.jdbc2.AbstractJdbc2Statement.execute(AbstractJdbc2Statement.java:451)
org.postgresql.jdbc2.AbstractJdbc2Statement.executeWithFlags(AbstractJdbc2Statement.java:336)
org.postgresql.jdbc2.AbstractJdbc2Statement.executeQuery(AbstractJdbc2Statement.java:235)
talend_reporting_etl.load_class_roster_fact_0_1.Load_Class_Roster_Fact.tPostgresqlInput_1Process(Load_Class_Roster_Fact.java:5507)
talend_reporting_etl.load_class_roster_fact_0_1.Load_Class_Roster_Fact.Create_Audit_1_tJava_2Process(Load_Class_Roster_Fact.java:3360)
talend_reporting_etl.load_class_roster_fact_0_1.Load_Class_Roster_Fact.Create_Audit_1_tPostgresqlCommit_1Process(Load_Class_Roster_Fact.java:3274)
talend_reporting_etl.load_class_roster_fact_0_1.Load_Class_Roster_Fact.Create_Audit_1_tPostgresqlInput_1Process(Load_Class_Roster_Fact.java:2823)
talend_reporting_etl.load_class_roster_fact_0_1.Load_Class_Roster_Fact.tPostgresqlConnection_1Process(Load_Class_Roster_Fact.java:819)
talend_reporting_etl.load_class_roster_fact_0_1.Load_Class_Roster_Fact.tJava_4Process(Load_Class_Roster_Fact.java:12623)
talend_reporting_etl.load_class_roster_fact_0_1.Load_Class_Roster_Fact.runJobInTOS(Load_Class_Roster_Fact.java:14079)
talend_reporting_etl.load_class_roster_fact_0_1.Load_Class_Roster_Fact.runJob(Load_Class_Roster_Fact.java:13818)
talend_reporting_etl.load_facts_0_1.Load_Facts.tRunJob_2Process(Load_Facts.java:1722)
talend_reporting_etl.load_facts_0_1.Load_Facts.tRunJob_1Process(Load_Facts.java:1654)
talend_reporting_etl.load_facts_0_1.Load_Facts.tRunJob_6Process(Load_Facts.java:1465)
talend_reporting_etl.load_facts_0_1.Load_Facts.tRunJob_5Process(Load_Facts.java:1353)
talend_reporting_etl.load_facts_0_1.Load_Facts.tRunJob_4Process(Load_Facts.java:1164)
talend_reporting_etl.load_facts_0_1.Load_Facts.tRunJob_3Process(Load_Facts.java:1052)
talend_reporting_etl.load_facts_0_1.Load_Facts.tRunJob_8Process(Load_Facts.java:863)
talend_reporting_etl.load_facts_0_1.Load_Facts.tRunJob_7Process(Load_Facts.java:674)
talend_reporting_etl.load_facts_0_1.Load_Facts$1.run(Load_Facts.java:3722)

We were wondering what the:
org.postgresql.core.v3.QueryExecutorImpl.execute(QueryExecutorImpl.java:192)
- locked org(dot)postgresql(dot)core(dot)v3(dot)QueryExecutorImpl(at)18493c9

was refering to.

Any direction for debugging would be useful. I'm not really that knowledgeable in the Java area
and my developers are a bit stumped.

Thanks

Dave