[Soot-list] Soot-2.4.0 bug? SynchObliviousMhpAnalysis.java:288 throws java.util.ConcurrentModificationException

[paris yiapa]

Hi Jeff,

The problem is that you are modifying the collection while you are iterating
through. This is not allowed with fail-fast iterators. It throws an
exceptions as this can cause unpredictable results.

You could try maybe using some collection that supports concurrent
modification.

Or maybe you find a way around this.

For example (if I remember well), using a HashMap you could have the same
problems. However, if you get the keySet of the map, you could go through
the collection without using the iterator and inspect the items with
.get(..) and subsequently remove the ones you want.

I hope that helps.

- Paris


On Thu, Jun 24, 2010 at 12:32 PM, Jeff <jeffwalt630 at gmail.com> wrote:

>
> Dear Eric and all,
>
> I am using Soot-2.4.0 to analyze a multi-threaded application and the
> following exception crashes the program:
>
> Caused by: java.util.ConcurrentModificationException
>     at
> java.util.AbstractList$Itr.checkForComodification(AbstractList.java:372)
>     at java.util.AbstractList$Itr.next(AbstractList.java:343)
>     at
> soot.jimple.toolkits.thread.mhp.SynchObliviousMhpAnalysis.run(SynchObliviousMhpAnalysis.java:288)
>     at
> soot.jimple.toolkits.thread.mhp.SynchObliviousMhpAnalysis.buildMHPLists(SynchObliviousMhpAnalysis.java:61)
>     at
> soot.jimple.toolkits.thread.mhp.SynchObliviousMhpAnalysis.<init>(SynchObliviousMhpAnalysis.java:47)
>     at
> soot.jimple.toolkits.thread.mhp.UnsynchronizedMhpAnalysis.<init>(UnsynchronizedMhpAnalysis.java:7)
>     at
> edu.hkust.clap.transformer.phase1.WholeProgramTransformer.internalTransform(WholeProgramTransformer.java:47)
> .....
>
>
> The corresponding source code @ SynchObliviousMhpAnalysis.run:
>
>         boolean addedNew = true;
>         while(addedNew)
>         {
>             addedNew = false;
>             Iterator<AbstractRuntimeThread> it =
> runAtOnceCandidates.iterator();
>             while(it.hasNext())
>             {
> 288:          AbstractRuntimeThread someThread = it.next();
>                 SootMethod someStartMethod =
> someThread.getStartStmtMethod();
>                 if(mayHappenInParallelInternal(someStartMethod,
> someStartMethod))
>                 {
>                     MHPLists.add(someThread); // add a second copy of it
>                     someThread.setStartMethodMayHappenInParallel();
>                     someThread.setRunsMany();
>  295:             runAtOnceCandidates.remove(someThread);
>                     if(optionPrintDebug)
>                         G.v().out.println(someThread.toString());
>                     addedNew = true;
>                 }
>             }
>         }
>
>
> Clearly the problem is caused by invoking "next()" on the List
> "runAtOnceCandidates" at line 288 after calling "remove()" at line 295 on
> it.
>
>
> -Jeff
>
>
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