NullPointerException in TimerUtil.java

Flowable Engine
1

Hi Team,

we are migrating from Activiti to Flowable and facing the problem using timers. Everything was working fine with Activiti and Flowable v5.

public enum TimeCycleDefinition {

EVERY_DAY("0 0 12 * * ?", "Every day (default)"), // every day at 12:00
EVERY_2DAYS("0 0 12 1/2 * ?", "Every other day"), // every 2 days at 12:00
EVERY_3DAYS("0 0 12 1/3 * ?", "Every three days"), // every 3 days at 12:00
EVERY_5DAYS("0 0 12 1/5 * ?", "Every five days"), // every 5 days at 12:00
EVERY_10DAYS("0 0 12 1/10 * ?", "Every ten days"), // every 10 days at 12:00
EVERY_HOUR("0 0 0/1 * * ?", "Every hour"), // every hour
EVERY_4HOURS("0 0 0/4 * * ?", "Every 4 hours"), // every 4 hours
EVERY_8HOURS("0 0 0/8 * * ?", "Every 8 hours"), // every 8 hours
EVERY_12HOURS("0 0 0/12 * * ?", "Every 12 hours"), // every 12 hours
EVERY_MIN("0 0/1 * * * ?", "Every 1 min (test)"), // every minute (TEST)
NONE("0 0 0 1 1 ? 1970", "None"); // this event will never fire

private final String value;
private final String label;

…
}

If using the NONE value for timeCycle,

Flowable engine fails with NPE.

20:28:04,287 ERROR AbstractCommandContext:100 - Error while closing command context
java.lang.NullPointerException
at org.flowable.engine.impl.util.TimerUtil.createTimerEntityForTimerEventDefinition(TimerUtil.java:154)

…
if (repeat) {
String prepared = prepareRepeat(dueDateString);
timer.setRepeat(prepared);
}

Here timer is null.

We use org.flowable.spring.SpringAdvancedBusinessCalendarManagerFactory

2

Hi Alex,

I tried to reproduce the issue. Without success.
Could you try to reproduce the issue in the jUnit test please?
mvn archetype to generate jUnit test template:

mvn archetype:generate -DarchetypeGroupId=org.flowable -DarchetypeArtifactId=flowable-archetype-unittest -DarchetypeVersion=6.0.1 -DgroupId=org.flowable -DartifactId=junittest

Regards
Martin

3

Hi Martin,

Here is the link
https://drive.google.com/open?id=0B60Jt3r-RIpTeHBhdG5fVUpxR1k

I could not upload the file to the ticket, it allows only images.

Thank you
Alexander

4

Looking at the code in TimerUtil it appears that a duedate must be set to instantiate the timer variable.

Line 119:

        TimerJobEntity timer = null;
        if (duedate != null) {
            timer = Context.getCommandContext().getTimerJobEntityManager().create();

This was changed with commit 3c1c6e5ae532fd6793e1c474100e32ff2eaea705 on July 16, 2015. Prior to that commit the timer object was always allocated and not null.

5

Hi,

@Alex: thanks a lot for the test. The test helped me a lot to create a pull request
David is right.
I created a pull request to fix the feature
https://github.com/flowable/flowable-engine/pull/425

The question is what is mandatory for the timer to be created.

Regards
Martin

6

DueDate is mandatory. Tijs fixed NPE with https://github.com/flowable/flowable-engine/commit/3b9e9ec3ffaa9688e876fb594b4c0b9644258274

7

Hi Tijs, Martin

How can I disable the timer in this case? Before I used “0 0 0 1 1 ? 1970” specifically for this reason.

Thank you
Alexander

8

Hi Alexander,

The issue is that no due date can be determined with the example expression you used (0 0 0 1 1 ? 1970). You want no timer to be created in that case and the process just to continue?

Best regards,

Tijs

9

Hi Tijs, Martin

Yes, we have process definitions where the initiator might decide whether use notifications or not as a part of the process. It can be every day/hour etc. but also no notification at all.

Would it be possible not to create the timer if due date is overdue already?

Kind regards
Alexander

10

@alex.chabatar : do you mean a boundary timer event that may or may not be active dependening on the input of the initiator? Imho, the better solution would be to have an expression that evaluates a condition whether or not the boundary event should be created (and not only for timers). wdyt?