[Pljava-dev] stack depth limit exceeded (NOT from infinite recursion)

Hi Thomas,

Thanks a lot for the info. I went through reorganizing the installed
jar file and reduced the size of the jar file to contain about 263
required class files (as compared to thousands originally). Then I
re-ran the 3rd party connection from within pljava again and still
seeing the same 'stack depth limit exceeded' problem.

May I know what is the stack depth limit for the second thread that
spawned from pljava? As of now, I have no idea how to work around this
problem.

Thanks so much.

Regards,
Kong

Thomas Hallgren wrote:

> OK, I see the problem. The connection spawns a new thread, that thread
> loads classes. And of course, the stack of that thread cannot be
> compared to the stack of the caller thread. PostgresSQL (since it's
> singlethreaded) thinks that you eat a vast amount of stack.
>
> I'll address this on the PostgreSQL hackers mailing list and see if I
> can convince them to install something that makes it possible to
> temporary shut off the stack-check. A temporary work-around is to
> reference the needed classes before making the connect call. That way,
> the current thread will be the one who loads them.
>
> Regards,
> Thomas Hallgren
>
>
> kstian wrote:
>
>> Hi Thomas,
>>
>> Thanks for replying.
>>
>> I have gradually increased max_stack_depth in postgresql.conf to
>> 16384 (verified from show all in the db) but it did not seem to help.
>>
>> The following is the code I have for the trigger function.
>> Basically, what I wanted it to do is, upon data update, I wanted to
>> connect to serivcemix (jbi container) and publish the event to
>> activeMQ. The problem happened on the line where I marked "==>
>> <==". I also printed out the loaded classes from sqlj.Loader.java in
>> findClass method and it showed a lot of loaded classes. These
>> classes were to be passed to sql statement for loading.
>>
>> =================================
>> mport java.sql.SQLException;
>> import java.sql.ResultSet;
>> import java.util.logging.Logger;
>>
>> import org.postgresql.pljava.TriggerData;
>> import org.postgresql.pljava.TriggerException;
>>
>>
>> import javax.jms.Connection;
>> import javax.jms.JMSException;
>> import javax.jms.Session;
>> import javax.jms.MessageProducer;
>>
>> import org.activemq.ActiveMQConnectionFactory;
>> import org.activemq.ActiveMQConnection;
>> import org.activemq.message.ActiveMQTopic;
>>
>> public class Triggers {
>>
>> public static void afterUpdateTsr(TriggerData td) throws
>> SQLException, JMSException
>> {
>> if (td.isFiredForStatement())
>> throw new TriggerException(td, "Cannot process statement
>> events.");
>> if (td.isFiredBefore())
>> throw new TriggerException(td, "Must be fired after event.");
>> if (!td.isFiredByUpdate())
>> throw new TriggerException(td, "Can only process UPDATE
>> event");
>> ResultSet _new = td.getNew();
>> ResultSet _old = td.getOld();
>> String[] args = td.getArguments();
>> String status = args[1];
>> if (args.length != 1)
>> throw new TriggerException(td, "One argument is expected.");
>> Logger log = Logger.getAnonymousLogger();
>> log.info("After UPDATE to tservicerequest table with new
>> tstatus = " + _new.getString(status) + ", old tstatus = " +
>> _old.getString(status));
>> ActiveMQConnectionFactory factory = new
>> ActiveMQConnectionFactory(ActiveMQConnection.DEFAULT_USER,
>> ActiveMQConnection.DEFAULT_PASSWORD,
>> ActiveMQConnection.DEFAULT_BROKER_URL); //"tcp://localhost:61616");
>> ActiveMQTopic pubTopic = new
>> ActiveMQTopic("demo.org.servicemix.source");
>> //ActiveMQTopic subTopic = new
>> ActiveMQTopic("demo.org.servicemix.result");
>> log.info("Connecting to JMS Server...");
>> Connection connection = factory.createConnection();
>> log.info("Before setClientID");
>> ==>connection.start(); <==
>> Session session = connection.createSession(false,
>> Session.AUTO_ACKNOWLEDGE);
>> MessageProducer producer = session.createProducer(pubTopic);
>> //connection.start();
>> log.info("Sending request to JMS Server...");
>> producer.send(session.createTextMessage("New tstatus= " +
>> _new.getString(status) + ", old tstatus= " + _old.getString(status)));
>> log.info("Sent message: New tstatus= " +
>> _new.getString(status) + ", old tstatus= " + _old.getString(status));
>> //connection.close();
>>
>> }
>> }
>>
>> ===============================================
>>
>> Thanks a lot for help.
>>
>> Regards,
>> Kong
>>
>> Thomas Hallgren wrote:
>>
>>> kstian wrote:
>>>
>>>> Hi,
>>>>
>>>> I created the following Trigger and Function:
>>>>
>>>> ======================================
>>>> CREATE FUNCTION afterUpdateTsr()
>>>> RETURNS trigger
>>>> AS 'pljava.Triggers.afterUpdateTservicerequest'
>>>> LANGUAGE java;
>>>>
>>>> CREATE TRIGGER tsr_afterUpdate
>>>> AFTER UPDATE ON tsr
>>>> FOR EACH ROW
>>>> EXECUTE PROCEDURE afterUpdateTsr(name);
>>>> ==========================================
>>>>
>>>> Then in the afterUpdateTsr() java function, I was writing codes to
>>>> connect to servicemix (a JBI container).
>>>>
>>>> In order to do that, I had to install 11 jar files in my postgresql
>>>> table using sqlj.install_jar function.
>>>>
>>>> When the aferUpdateTsr() got triggered, it was throwing "stack
>>>> depth limit exceeded" exception from native C. (I believed it's
>>>> from ExecutionPlan.c). I also printed out the loaded classes from
>>>> sqlj/Loader.java (findClass function) and found that pljava was
>>>> loading a lot of classes.
>>>> Was it the main reason causing this exception? How do I resolve
>>>> this problem?
>>>>
>>> Normally, a "stack depth limit exceeded" exception is caused by a
>>> function that calls SQL, that in turn calls a function that calls
>>> SQL, etc. until you recurse so deep that the PostgreSQL callstack is
>>> exhausted. If it's a controlled and expected recursion you can try
>>> to increase the max_stack_depth variable in your postgresql.conf
>>>
>>> If you this doesn't help, then I'll have to know a bit more about
>>> what your triggers are doing in order to assist you.
>>>
>>> Kind regards,
>>> Thomas Hallgren
>>>
>>>
>>>
>>>
>>>
>>>
>>
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