Memory usage in Workflow wait states

[zazzaz]

Hi all,
i'm using jbpm tom develop a workflow use case.

Suppose you run 1000 (or an high number you can decide) workflows and suppose each of them stops waiting for a message from someone. Suppose the workflow instances are running on the same machine. Then suppose that the response the wait state is waiting for will arrive in one week.
Will the 1000 instances be in memory for 7 days (or until they receive the message) or will they be swapped to make space for other instances?
Thanks a lot for answering in this period. bye!

[kukeltje]

Will the 1000 instances be in memory for 7 days (or until they receive the message)

no

[or will they be swapped to make space for other instances?

no

They are just in the database

[zazzaz]

Hi,
thanks for previous reply!

One more question, so I can continue my work.

Is the database memorization an automatic thing?

Thanks a lot. Bye

[kukeltje]

what is 'database memorization'?

[zazzaz]

Are the process instances saved in the database automatically when they reach a wait state that takes a lot to be completed (without using CPU)?

[kukeltje]

Are the process instances saved in the database automatically when they reach a wait state

Yes

hat takes a lot to be completed (without using CPU)?

??? what do you mean here?

[zazzaz]

Thanks again.
The situation is the syncronization on a shared object.

Suppose in the wait state we have a code such

myObject.wait()

(or a similar method call that may block this process instance).


Will the process instance be saved automatically and free the memory it holded?

Bye

[kukeltje]

don't do wait() in nodes/states/actions unless they are async... If it is in a wait it is 'working' and not persisted

[zazzaz]

ok,
now it's all perfect.
The solution is

persisting the instance
wait for the asynch call to complete
restore the instance and give it the call result

Bye

[kukeltje]

and the nice thing is... all three happen automatically in jBPM..

[zazzaz]

Excellent
So If I write a library for receiving message and an asynchronus receive call takes one day to be completed, the process instance is automatically saved!

Will the instance be removed from runtime memory usage or not?

[zazzaz]

Excellent
And will it free the memory of the process instance when it saves it and waits for the asynchronus call to be completed?

[kukeltje]

no, it will keep everything in memory as is very good practice. these days since memory is cheap. Besides that...if your jbpm engine handles more than 100 process instances per day (not specifically new ones), you have to restart your j2ee server each day. If you handle more than 1000 instances a day you have to reset your j2ee server each day and your hardware each week.

[jeffcwang]

Hello Ronald,

Can you please elaborate on why you'd have to restart the j2ee server each day if JBPM handles > than 100 process instances/day? Does JBPM have a problem scaling? It seems like 100 process instances isn't that many...

thanks

[zazzaz]

Ok,
my situation is the following.
I've to execute a very large number of process instances but they're not started all in the same time.
This number can be even 1 million per day!
Some of this instances will live for a few minutes, since the answer they wait for arrives soon, while the others will wait days...
So can I free the useless memory usage of this kind of processes (since they're doing no work at all) or not?