[KARAF-6068] Karaf hangs by bundle resolving (felix resolver)

• Type: Bug
• Status: Open
• Priority: Critical
• Resolution: Unresolved
• Affects Version/s: 4.0.7, 4.1.5
• Component/s: karaf

Environment

JDK 8
Windows, Linux

• Assignee: Unassigned
• Reporter: Andrei Shakirin
• Created: 30/Dec/18 12:48
• Updated: 08/Oct/20 14:21

Description

I faced following situation in project uses Karaf as deployment container for microservices:
1) bundle A is installed with feature A and exports java packages xxx.yyy in version 10.2.0
2) additionally, bundle B was created and installed with feature B. Bundle B exporting the same java packages (xxx.yyy) as bundle A, but with another version 1.1.0

Problem: as soon as other modules importing java packages (xxx.yyy) with version [1.1, 2.0) - Karaf completely hangs on startup. There are no logs describing the problem. The last log statement is about JMX registration.
Karaf JVM takes about 90% CPU - looks like infinite loop.

The thread dump shows that threads occupied CPU are the following:

"pool-38-thread-8" #245 prio=5 os_prio=0 tid=0x000000001cd94000 nid=0x3094 runnable [0x0000000029f0e000]
   java.lang.Thread.State: RUNNABLE
        at org.apache.felix.resolver.util.ArrayMap.getOrCompute(ArrayMap.java:74)
        at org.apache.felix.resolver.ResolverImpl.addUsedBlame(ResolverImpl.java:1284)
        at org.apache.felix.resolver.ResolverImpl.mergeUses(ResolverImpl.java:1110)
        at org.apache.felix.resolver.ResolverImpl.mergeUses(ResolverImpl.java:1111)
        at org.apache.felix.resolver.ResolverImpl.mergeUses(ResolverImpl.java:1111)
        at org.apache.felix.resolver.ResolverImpl.mergeUses(ResolverImpl.java:1105)
        at org.apache.felix.resolver.ResolverImpl.mergeUses(ResolverImpl.java:1105)
        at org.apache.felix.resolver.ResolverImpl.mergeUses(ResolverImpl.java:1105)
        at org.apache.felix.resolver.ResolverImpl.mergeUses(ResolverImpl.java:1105)
        at org.apache.felix.resolver.ResolverImpl.mergeUses(ResolverImpl.java:1105)
        at org.apache.felix.resolver.ResolverImpl.computeUses(ResolverImpl.java:872)
        at org.apache.felix.resolver.ResolverImpl.access$500(ResolverImpl.java:59)
        at org.apache.felix.resolver.ResolverImpl$6.run(ResolverImpl.java:1231)
        at org.apache.felix.resolver.ResolverImpl$EnhancedExecutor$1.run(ResolverImpl.java:2442)
        at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1149)
        at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:624)
        at java.lang.Thread.run(Thread.java:748)

Full logs and thread dumps are attached.

The problem makes diagnostic of package exports/imports issues completely impossible.
I will try to reproduce it on simple example, but perhaps you can start analyse based om thread dumps.