[GROOVY-9574] ConcurrentModificationException in Java9.concealedPackageList

• Type: Bug
• Status: Closed
• Priority: Major
• Resolution: Fixed
• Affects Version/s: 3.x
• Fix Version/s: 4.0.0-alpha-1, 3.0.5
• Component/s: groovy-runtime
• Environment: Groovy v3.0.3 ; # java -version ; openjdk version "11.0.6" 2020-01-14 ; OpenJDK Runtime Environment AdoptOpenJDK (build 11.0.6+10) ; OpenJDK 64-Bit Server VM AdoptOpenJDK (build 11.0.6+10, mixed mode)
• Assignee: Daniel Sun
• Reporter: Ilya Lipnitskiy
• Created: 26/May/20 22:20
• Updated: 23/Jul/20 14:16
• Resolved: 28/May/20 01:07

Description

Facing the following exception in a multithreaded environment with multiple threads executing the same Groovy code (@CompileStatic is not used). HashMap is not reentrant, but computeIfAbsent may insert an element if a key is missing. If another thread is iterating through the map at the same time, I can see why this exception is being raised. Is the fix as simple as replacing HashMap with ConcurrentHashMap, or are there performance implications?

java.util.ConcurrentModificationException
at java.base/java.util.HashMap.computeIfAbsent(HashMap.java:1134)
 at org.codehaus.groovy.vmplugin.v9.Java9.concealedPackageList(Java9.java:402)
 at org.codehaus.groovy.vmplugin.v9.Java9.isExportedForIllegalAccess(Java9.java:373)
 at org.codehaus.groovy.vmplugin.v9.Java9.checkAccessible(Java9.java:353)
 at org.codehaus.groovy.vmplugin.v9.Java9.doTransformMetaMethod(Java9.java:266)
 at org.codehaus.groovy.vmplugin.v9.Java9.getOrTransformMetaMethod(Java9.java:253)
 at org.codehaus.groovy.vmplugin.v9.Java9.transformMetaMethod(Java9.java:244)
 at org.codehaus.groovy.vmplugin.v8.Java8.transformMetaMethod(Java8.java:613)
 at org.codehaus.groovy.runtime.callsite.PojoMetaMethodSite$PojoCachedMethodSite.<init>(PojoMetaMethodSite.java:184)
 at org.codehaus.groovy.runtime.callsite.PojoMetaMethodSite$PojoCachedMethodSiteNoUnwrap.<init>(PojoMetaMethodSite.java:198)
 at org.codehaus.groovy.runtime.callsite.PojoMetaMethodSite.createCachedMethodSite(PojoMetaMethodSite.java:160)
 at org.codehaus.groovy.runtime.callsite.PojoMetaMethodSite.createPojoMetaMethodSite(PojoMetaMethodSite.java:151)
 at groovy.lang.MetaClassImpl.createPojoCallSite(MetaClassImpl.java:3487)
 at org.codehaus.groovy.runtime.callsite.CallSiteArray.createPojoSite(CallSiteArray.java:123)
 at org.codehaus.groovy.runtime.callsite.CallSiteArray.createCallSite(CallSiteArray.java:160)
 at org.codehaus.groovy.runtime.callsite.CallSiteArray.defaultCall(CallSiteArray.java:47)
 at org.codehaus.groovy.runtime.callsite.AbstractCallSite.call(AbstractCallSite.java:125)
 at org.codehaus.groovy.runtime.callsite.AbstractCallSite.call(AbstractCallSite.java:148)