[rules-users] ResourceChangeScanner not picking up changes deployed to Guvnor

[Peter Butler]

We're using Drools 5.0.1.SNAPSHOT 26353:26357M in JBoss 4.2.3. We're 
still in UAT so we've got our rules in Guvnor so that the business 
analysts can deploy changes quickly, they create snapshots in Guvnor 
that are picked up by the application. The problem is that sometimes 
creating a snapshot in Guvnor means that the ResourceChangeScanner in 
the application removes the changeset for the rule package that has changed.

Here is the changeset config:

<change-set xmlns="http://drools.org/drools-5.0/change-set" 
xmlns:xs="http://www.w3.org/2001/XMLSchema-instance" 
xs:schemaLocation="http://drools.org/drools-5.0/change-set.xsd" >
    <add>
        <resource 
source="http://localhost/drools-guvnor/org.drools.guvnor.Guvnor/package/cover/cover" 
type="PKG" />
        <resource 
source="http://localhost/drools-guvnor/org.drools.guvnor.Guvnor/package/question/question" 
type="PKG" />
        <resource 
source="http://localhost/drools-guvnor/org.drools.guvnor.Guvnor/package/referral/referral" 
type="PKG" />
        <resource 
source="http://localhost/drools-guvnor/org.drools.guvnor.Guvnor/package/validation/validation" 
type="PKG" />         
    </add>
</change-set>

These are picked up OK when the application starts (I've elided the 
timestamps from the log file entries for readability):

KnowledgeAgent building resource=[UrlResource 
path='http://localhost/drools-guvnor/org.drools.guvnor.Guvnor/package/validation/validation']
KnowledgeAgent adding KnowledgeDefinitionsPackage validation
KnowledgeAgent building resource=[UrlResource 
path='http://localhost/drools-guvnor/org.drools.guvnor.Guvnor/package/question/question']
KnowledgeAgent adding KnowledgeDefinitionsPackage question
KnowledgeAgent building resource=[UrlResource 
path='http://localhost/drools-guvnor/org.drools.guvnor.Guvnor/package/referral/referral']
KnowledgeAgent adding KnowledgeDefinitionsPackage referral
KnowledgeAgent building resource=[UrlResource 
path='http://localhost/drools-guvnor/org.drools.guvnor.Guvnor/package/cover/cover']
KnowledgeAgent adding KnowledgeDefinitionsPackage cover
KnowledgeAgent new KnowledgeBase now built and in use

And the ResourceChangeScanner then scans for changes every 60 seconds:

ResourceChangeScanner attempt to scan 4 resources
ResourceChangeScanner thread is waiting for 60

When we change the "referral" package and rebuild the snapshot so that 
the application can pick it up, here's what happens:

ResourceChangeScanner removed resource=[UrlResource 
path='http://localhost/drools-guvnor/org.drools.guvnor.Guvnor/package/referral/referral']
ResourceChangeNotification received ChangeSet notification
ResourceChangeScanner thread is waiting for 60
ResourceChangeNotification processing ChangeSet
ResourceChangeNotification ChangeSet removed resource=[UrlResource 
path='http://localhost/drools-guvnor/org.drools.guvnor.Guvnor/package/referral/referral'] 
for listener=org.drools.agent.impl.KnowledgeAgentImpl at 7a1b5b
KnowledgeAgent received ChangeSet changed notification
KnowledgAgent applying ChangeSet
KnowledgeAgent unsubscribing from resource=[UrlResource 
path='http://localhost/drools-guvnor/org.drools.guvnor.Guvnor/package/referral/referral']
ResourceChangeNotification unsubscribing 
listener=org.drools.agent.impl.KnowledgeAgentImpl at 7a1b5b to 
resource=[UrlResource 
path='http://localhost/drools-guvnor/org.drools.guvnor.Guvnor/package/referral/referral']
KnowledgeAgent ChangeSet requires KnowledgeBuilder
KnowledgeAgent ChangeSet requires KnowledgeBuilder
KnowledgeAgent ChangeSet requires KnowledgeBuilder
KnowledgeAgent rebuilding KnowledgeBase using ChangeSet
ResourceChangeNotification thread is waiting for queue update
KnowledgeAgent building resource=[UrlResource 
path='http://localhost/drools-guvnor/org.drools.guvnor.Guvnor/package/validation/validation']
KnowledgeAgent adding KnowledgeDefinitionsPackage validation
KnowledgeAgent building resource=[UrlResource 
path='http://localhost/drools-guvnor/org.drools.guvnor.Guvnor/package/question/question']
KnowledgeAgent adding KnowledgeDefinitionsPackage question
KnowledgeAgent building resource=[UrlResource 
path='http://localhost/drools-guvnor/org.drools.guvnor.Guvnor/package/cover/cover']
KnowledgeAgent adding KnowledgeDefinitionsPackage cover
KnowledgeAgent new KnowledgeBase now built and in use
ResourceChangeScanner attempt to scan 3 resources
ResourceChangeScanner thread is waiting for 60

 From this point on it seems to be impossible to get the 
ResourceChangeScanner to pick up the new "referral" snapshot. I've tried 
updating the changeset file and redeploying the snapshot but the 
application won't pick it up. This problem doesn't occur with every 
snapshot rebuild but it does happen quite frequently.

Has anyone else struck this problem? Is there any way around it?

Cheers

Peter Butler