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https://issues.apache.org/jira/browse/GROOVY-7535?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16017549#comment-16017549
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John Wagenleitner commented on GROOVY-7535:
-------------------------------------------
The {{AtomicInteger#get}} shouldn't lock but would be a {{volatile}} read (and
other methods use CAS and not locks). While I don't think having that volatile
read in {{hasCategoryInCurrentThread}} will cause too much of a performance
issue, I do agree that it's awkward to be using the {{AtomicInteger}} in the
synchronized blocks. Given that there is only a need to observe 0 or non-Zero
for {{categoriesInUse}} and a precise number does not matter, except when
decrementing which is synchronized. I also think the {{int}} counter version is
better as long as there's a [some
comment|https://github.com/apache/groovy/pull/540/commits/6fddddb2a39741d68358701230a929728338e7aa]
to explain why there is no synchronized read in
{{hasCategoryInCurrentThread}}. In either case, I think one additional change
should be to deprecate the {{hasCategoryInAnyThread}} method.
I think the original fix that was put into 2.4.6 did not fix the issue and may
have just reduced the number of instructions that the threads could interleave
on in order to reproduce. I'd like to see what others think, if in agreement
then as [~paulk] mentioned this should be re-opened.
> 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, locking.png, 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.
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