Clarity Processes that use GEL are getting stuck in sleep

Products

• Clarity PPM On Premise
• Clarity PPM SaaS

Issue/Introduction

Some processes that use GEL are not completing in Clarity. If you create a process with just a start and finish step, and nothing else, the process completes successfully, but those using GEL are not completing.

Environment

Any Clarity environment that uses processes with gel scripts

Cause

This can happen if the util:sleep command is in the gel scripts.  

You should avoid using util:sleep in GEL scripts. This tag puts the thread executing the GEL script to sleep. There are 15 GEL threads allocated per Process Engine instance. If all 15 are sleeping, other GEL steps will be unable to execute and processes will appear to hang.  Having most or even some of your gel threads sleeping can cause slow performance on your process engines.

Resolution

Short Term Solution:

• Restart the bg services. Usually one restart suffices. But sometimes multiple restarts will be required.

The problem with restarting the bg process one or more times to resolve this problem is that the problem is likely to reoccur.  The more gel script processes you run using this tab, the more likely this problem is to reoccur.

Long Term Solution:

• Rewrite process gel scripts so that they do not use util:sleep.
• We at Broadcom Support strongly discourage using this tag

Instead of using util:sleep a better way is to move the check to a post condition.  Assuming your GEL script is trying to monitor the step completion in some other process instance you could have that process set a flag/value on an object that can trigger an event that the post condition in your monitoring process can detect before it moves on. 

That may mean breaking your existing process and GEL script into multiple pieces rather than one bigger process. 

That may also mean your process logic needs to be rethought to use a custom object or custom attribute on some other object that can used in your process in a post condition. 

Additional Information

Because the post condition pipeline can handle and iterate through many post conditions without clogging up its bandwidth, fixing your processes so that they use post conditions instead of util:sleep will allow your to sure that this problem won't occur again.. 
You could have 300+ process instances waiting on a post condition without affecting process engine performance, whereas even a few GEL scripts stuck sleeping or polling can have an adverse affect on the system throughput and behavior.