AussieGuy0 / Drools-Bug

Drools Bug

Using this repo

Running

Prereqs: Have Java 11 and Tomcat 9 installed

1. Run mvn package in root directory
2. Move test.war to tomcat webapps directory
3. Restart tomcat
4. Make a GET request to localhost:8080/test/trigger?drl=big (curl localhost:8080/test/trigger?drl=big)
5. Error will occur and sent back as response

Files

• EstimatorSevlet: A servlet that runs the rule compilation
• catalina-example.log: Snippet of tomcat catalina log that shows error messages
• localhost-example.log: Snippet of tomcat localhost log that shows error messages

Bug Description

Summary

When large rule (.drl) files are complied with the security manager turned on in a servlet container (e.g. Tomcat), it causes AccessControlExceptions, which causes NoClassDefFoundErrors.

Steps

Prereqs: Program is run in servlet context (e.g .war file in tomcat)

1. Turn on security manager
2. Provide policy files through the properties java.security.policy and kie.security.policy
3. Compile a .drl file that has more than parallelRulesBuildThreshold (default: 10) rules

Expected Result

Rules are compiled successfully

Actual Result

No class def error

Cause

In KnowledgeBuilderImpl, a ForkJoinPool is created and used for parallel building. A ForkJoinPool with no ForkJoinWorkerThreadFactory specified, it will use a default factory that provides it's own permissions. These permissions are not sufficient for compiling drl files in a servlet context.

Potential Fix

A potential fix is to allow the user to provide their own ForkJoinWorkerThreadFactory as a configuration option for drools.