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Jochen Kemnade commented on GROOVY-7535: ---------------------------------------- With the PR, all writes are synchronized. Here's why I think that the reads are fine without synchronization/{{volatile}} (correct me if I'm wrong): Even if each thread uses its working copy of the {{categoriesInUse}} field , the copy may have the wrong value, but it can not be "significantly wrong". The other thread may have incremented the value, but not from 0 to 1 as the current thread will already have set it to a value {{>0}}, so it won't change the value of {{categoriesInUse == 0}}, which is the only thing that matters for the early exit in {{hasCategoryInCurrentThread}}. The other thread may also have decremented the value, but it cannot have set it to 0 if the current thread incremented it in {{newScope}}, so it would not have effected {{categoriesInUse == 0}} either. > Groovy category throwing MissingMethodException and MissingPropertyException > when using multiple threads > -------------------------------------------------------------------------------------------------------- > > Key: GROOVY-7535 > URL: https://issues.apache.org/jira/browse/GROOVY-7535 > Project: Groovy > Issue Type: Bug > Affects Versions: 2.3.11, 2.4.4 > Environment: I have been able to reproduce this issue on a Cent O/S > version 6.4 with Java 64 Bit JDK 1.8 and groovy 2.4.4. > Reporter: James Oswald > Assignee: Pascal Schumacher > Fix For: 2.4.6 > > Attachments: > 0001-GROOVY-7535-fix-race-condition-between-the-modificat.patch, > CategoryTest.groovy, exceptionForCategoryTest.txt, > exceptionForTimeCategoryTest.txt, Test.groovy, TimeCategoryTest.groovy > > > When using groovy use block, we randomly get > groovy.lang.MissingPropertyException when trying to access a property off a > category. (Attached is an example) > {quote} > index 76 > Exception in thread "Thread-77" groovy.lang.MissingPropertyException: No such > property: millisecond for class: java.lang.Integer > at > org.codehaus.groovy.runtime.ScriptBytecodeAdapter.unwrap(ScriptBytecodeAdapter.java:51) > at > org.codehaus.groovy.runtime.callsite.PojoMetaClassGetPropertySite.callGetProperty(PojoMetaClassGetPropertySite.java:43) > at > TimeCategoryTest$__spock_initializeFields_closure1$_closure4$_closure5.doCall(TimeCategoryTest.groovy:23) > at > TimeCategoryTest$__spock_initializeFields_closure1$_closure4$_closure5.doCall(TimeCategoryTest.groovy) > at sun.reflect.GeneratedMethodAccessor12.invoke(Unknown Source) > at > sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43) > at java.lang.reflect.Method.invoke(Method.java:497) > at > org.codehaus.groovy.reflection.CachedMethod.invoke(CachedMethod.java:90) > at groovy.lang.MetaMethod.doMethodInvoke(MetaMethod.java:324) > at > org.codehaus.groovy.runtime.metaclass.ClosureMetaClass.invokeMethod(ClosureMetaClass.java:292) > at > groovy.lang.MetaClassImpl.invokeMethod(MetaClassImpl.java:1016) > at groovy.lang.Closure.call(Closure.java:423) > at groovy.lang.Closure.call(Closure.java:417) > at > org.codehaus.groovy.runtime.GroovyCategorySupport$ThreadCategoryInfo.use(GroovyCategorySupport.java:109) > at > org.codehaus.groovy.runtime.GroovyCategorySupport$ThreadCategoryInfo.access$400(GroovyCategorySupport.java:65) > at > org.codehaus.groovy.runtime.GroovyCategorySupport.use(GroovyCategorySupport.java:249) > at > org.codehaus.groovy.runtime.DefaultGroovyMethods.use(DefaultGroovyMethods.java:403) > {quote} > or groovy.lang.MissingMethodException when trying to access a method from a > category. > {quote} > index 82 > Exception in thread "Thread-207" groovy.lang.MissingMethodException: No > signature of method: java.lang.String.test() is applicable for argument > types: (java.lang.String) values: [ bar] > Possible solutions: next(), toSet(), getAt(java.lang.String), wait(). trim(), > toList() > at > org.codehaus.groovy.runtime.ScriptBytecodeAdapter.unwrap(ScriptBytecodeAdapter.java:56) > at > org.codehaus.groovy.runtime.callsite.PojoMetaClassSite.call(PojoMetaClassSite.java:46) > at > org.codehaus.groovy.runtime.callsite.AbstractCallSite.call(AbstractCallSite.java:122) > at > CategoryTest$__spock_initializeFields_closure1$_closure5.doCall(CategoryTest.groovy:24) > at > CategoryTest$__spock_initializeFields_closure1$_closure5.doCall(CategoryTest.groovy) > at sun.reflect.GeneratedMethodAccessor12.invoke(Unknown Source) > at > sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43) > at java.lang.reflect.Method.invoke(Method.java:497) > at > org.codehaus.groovy.reflection.CachedMethod.invoke(CachedMethod.java:90) > at groovy.lang.MetaMethod.doMethodInvoke(MetaMethod.java:324) > at > org.codehaus.groovy.runtime.metaclass.ClosureMetaClass.invokeMethod(ClosureMetaClass.java:292) > at > groovy.lang.MetaClassImpl.invokeMethod(MetaClassImpl.java:1016) > at groovy.lang.Closure.call(Closure.java:423) > at groovy.lang.Closure.call(Closure.java:417) > at > org.codehaus.groovy.runtime.GroovyCategorySupport$ThreadCategoryInfo.use(GroovyCategorySupport.java:109) > at > org.codehaus.groovy.runtime.GroovyCategorySupport$ThreadCategoryInfo.access$400(GroovyCategorySupport.java:65) > at > org.codehaus.groovy.runtime.GroovyCategorySupport.use(GroovyCategorySupport.java:249) > at > org.codehaus.groovy.runtime.DefaultGroovyMethods.use(DefaultGroovyMethods.java:403) > {quote} > On the server, either one of these exceptions to appear every few days or > weeks. > I found a similar issue GROOVY-2105 which contains a test that reproduces > this problem on Linux. Looking back the fix that was implemented for this > ticket was to add synchronized to 3 methods. These changes were late removed > in a refactor of GroovyCategorySupport. > I have attached 3 test cases that reproduce the threading issue. > NOTE: problem does not happen 100% of the time as it is a threading and > timing issue, so you may have to play with the number of threads to generate > the exception. What I have attached generates the exception on my linux box > most of the time. -- This message was sent by Atlassian JIRA (v6.3.15#6346)