[rules-users] Timer does not return!
Kris Verlaenen
Kris.Verlaenen at cs.kuleuven.be
Fri Jun 12 11:08:12 EDT 2009
> Any ideas when will this fix find its way into an official release.
We're trying to do more regular releases now, every 4-6 weeks hopefully.
At this point, we're trying to release something around the end of the
month.
> Suggestion: Would it make send for the End node (with terminate ==
> true) to call ksession.halt?
Not sure you want to embed that knowledge in your process. If you are
using a separate session for each process instance, it could make sense
to halt once its completed. But even in that case, I'd prefer attaching
a process listener to the session that listens for the completion of the
process instance. This keeps this implementation choice from your
process logic then. In general, you just call halt() when you're done
processing. For long-running sessions, you might even never call it.
Kris
>
> Ajay Gautam
>
> -----Original Message-----
> From: Kris Verlaenen [mailto:Kris.Verlaenen at cs.kuleuven.be]
> Sent: Friday, June 12, 2009 3:59 AM
> To: Gautam, Ajay, GBM
> Cc: rules-users at lists.jboss.org
> Subject: RE: [rules-users] Timer does not return!
>
> Ajay,
>
> Apparently the engine is in a deadlock in this specific situation.
> The
> reason is that, while in reactive mode (using fireUntilHalt()), the
> engine does not accept any fireAllRules() invocations (which is used
> internally in the process engine), and as a result blocks the
> process
> from continuing. In reactive mode, the engine should however simply
> ignore fireAllRules() invocations (as it is executing already).
> This
> has been fixed on trunk. So if you upgrade to the latest snapshot
> (either get it here
>
https://hudson.jboss.org/hudson/job/drools/lastSuccessfulBuild/artifact/trunk/target/
> or build locally), you should be fine.
>
> Regarding the second issue, what you are seeing is probably not the
> case
> that the process has not ended, but the fact that the application
> does
> not end automatically because the engine is still running in
> reactive
> mode in a separate thread. You can halt the engine by calling
> ksession.halt().
>
> Kris
>
> Quoting Ajay.Gautam at rbs.com:
>
> > Bump! Anyone?
> >
> >
> > -----Original Message-----
> >
> >
> > Thanks for the sample code Kris. It seems that the problem is not
> > with the Timer itself, but with WorkItemHadler !
> >
> > (Complete code - extended version of your code - is attached).
> Adding
> > a "Log" work item between START and the first Action breaks the
> code.
> > If I remove the Log item, the flow works as expected. Here is the
> > code that runs in executeWorkItem:
> >
> > logger.info("=== message from flow ===>> "+
> > workItem.getParameter("Message"));
> > manager.completeWorkItem(workItem.getId(), null);
> > logger.info("Work item completed!");
> >
> > the 2nd log message is not displayed!
> >
> > Any ideas what am I doing wrong?
> >
> >
> >
> > Second issue: The process does not end! - I took Kris's code and
> ran
> > it. Even after the work flow completed, the process was still
> alive!
> > (End Node's Terminate Property *is* set to "true").
> >
> >
> > Thanks
> >
> > Ajay
> >
> >
> > -----Original Message-----
> > From: Kris Verlaenen [mailto:Kris.Verlaenen at cs.kuleuven.be]
> > Sent: Friday, June 05, 2009 5:08 PM
> > To: Rules Users List; Gautam, Ajay, GBM
> > Cc: rules-users at lists.jboss.org
> > Subject: Re: [rules-users] Timer does not return!
> >
> > It's difficult to figure out what's going on without looking at
> the
> > process itself, but your code seems to be fine. If you run the
> > engine
> > in reactive mode (using fireUntilHalt), it should automatically
> fire
> > the
> > action associated with the timer once it goes off. Note that, if
> > you
> > are not running in reactive mode, the timer is also triggered (it
> > doesn't just run through), but it'll wait to execute the
> associated
> > action until fireAllRules is called.
> >
> > For example, this simple process is a timer followed by an action
> > writing out when the timer is being triggered.
> >
> > <?xml version="1.0" encoding="UTF-8"?>
> > <process xmlns="http://drools.org/drools-5.0/process"
> > xmlns:xs="http://www.w3.org/2001/XMLSchema-instance"
> > xs:schemaLocation="http://drools.org/drools-5.0/process
> > drools-processes-5.0.xsd"
> > type="RuleFlow" name="ruleflow" id="com.sample.ruleflow"
> > package-name="com.sample" >
> >
> > <header>
> > </header>
> >
> > <nodes>
> > <start id="1" name="Start" x="16" y="16" width="80"
> height="40"
> > />
> > <timerNode id="4" name="Timer" x="128" y="16" width="80"
> > height="40"
> > delay="2000" />
> > <actionNode id="2" name="Action" x="240" y="16" width="80"
> > height="40" >
> > <action type="expression" dialect="mvel"
> > >System.out.println("Executing");</action>
> > </actionNode>
> > <end id="3" name="End" x="352" y="16" width="80" height="40"
> />
> > </nodes>
> >
> > <connections>
> > <connection from="1" to="4" />
> > <connection from="4" to="2" />
> > <connection from="2" to="3" />
> > </connections>
> >
> > </process>
> >
> > By using the following code, the action is written out immediately
> > when
> > the timer triggers (after 2 seconds):
> >
> > public static final void main(String[] args) {
> > try {
> > // load up the knowledge base
> > KnowledgeBase kbase = readKnowledgeBase();
> > final StatefulKnowledgeSession ksession =
> > kbase.newStatefulKnowledgeSession();
> > new Thread(new Runnable() {
> > public void run() {
> > ksession.fireUntilHalt();
> > }
> > }).start();
> > // start a new process instance
> > ksession.startProcess("com.sample.ruleflow");
> > } catch (Throwable t) {
> > t.printStackTrace();
> > }
> > }
> >
> > The following code doesn't use reactive mode, so the action
> > associated
> > with the timer is only triggered during the next fireAllRules
> (after
> > 4
> > seconds).
> >
> > public static final void main(String[] args) {
> > try {
> > // load up the knowledge base
> > KnowledgeBase kbase = readKnowledgeBase();
> > final StatefulKnowledgeSession ksession =
> > kbase.newStatefulKnowledgeSession();
> > // start a new process instance
> > ksession.startProcess("com.sample.ruleflow");
> > Thread.sleep(4000);
> > ksession.fireAllRules();
> > } catch (Throwable t) {
> > t.printStackTrace();
> > }
> > }
> >
> > Hope this clears up the situation a little more. If you still
> have
> > problems integrating timers in your process, could you send a
> > standalone
> > example (containing both the process xml and the Java code)?
> >
> > Thx,
> > Kris
> >
> > Quoting Ajay.Gautam at rbs.com:
> >
> > > I have a timer in my code that does not return. It just hangs
> the
> > > process (with no CPU activity).
> > >
> > > Any idea what may be causing this?
> > >
> > > The timer delay is 2000 ms. Based on the docs, here are code
> > > snippets:
> > >
> > >
> > > .......
> > > ksession = kbase.newStatefulKnowledgeSession();
> > > new Thread(new Runnable() {
> > > public void run() {
> > > ksession.fireUntilHalt();
> > > }
> > > }).start();
> > > ........
> > > final RFQRequest req = createRequest();
> > > parameters.put("rfqIn", req);
> > > ksession.setGlobal("reqTag", req.getTag());
> > > ksession.startProcess("com.rbs.gbm.pm.RFQ-WorkFlow",
> parameters);
> > > ........
> > >
> > > If I remove the fireUntilHalt thread, the timer is not triggered
> > at
> > > all. The flow just passes through it lilke its not even there.
> > >
> > > Any help / info / pointers will be appreciated.
> > >
> > > Thanks
> > >
> > > Ajay
> > >
> > > *****Please note that my email address may have changed. For all
> > > future correspondence, please use this address*****
> > >
> > >
> > >
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> future correspondence, please use this address*****
>
>
> ********************************************************************This
> message (including any attachments) is confidential and/or
> privileged. It is to be used by the intended recipients only. If
> you have received it by mistake please notify the sender by return
> e-mail and delete this message from your system. Any unauthorized
> use or dissemination of this message in whole or in part is
> strictly prohibited. Please note that e-mails are inherently
> insecure and susceptible to change. The Royal Bank of Scotland
> Group, plc ("RBS") and its US subsidiaries, and affiliates and
> subsidiary undertakings, including but not limited to, RBS plc New
> York and Connecticut Branches, RBS Securities Inc., ABN AMRO Bank
> N.V. New York and Chicago Branches and, ABN AMRO Incorporated,
> Citizens Financial Group, Inc. and RBS Citizens, N.A., shall not be
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> any delay in its receipt or damage to your system. RBS does not
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> or services discussed herein are available or appropriate for sale
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> Those who utilize this information do so on their own initiative
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regulations.********************************************************************
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