java.util.ConcurrentModificationException
        at java.util.IdentityHashMap$IdentityHashMapIterator.nextIndex(IdentityHashMap.java:715)
        at java.util.IdentityHashMap$KeyIterator.next(IdentityHashMap.java:804)
        at org.netbeans.modules.timers.InstanceWatcher.contains(InstanceWatcher.java:78)
        at org.netbeans.modules.timers.InstanceWatcher.add(InstanceWatcher.java:72)
        at org.netbeans.modules.timers.TimesCollectorPeer$ObjectCountDescripton.add(TimesCollectorPeer.java:214)
        at org.netbeans.modules.timers.TimesCollectorPeer$ObjectCountDescripton.access$000(TimesCollectorPeer.java:189)
        at org.netbeans.modules.timers.TimesCollectorPeer.reportReference(TimesCollectorPeer.java:104)
        at org.netbeans.modules.timers.Install$TimerHandler.publish(Install.java:132)
        at java.util.logging.Logger.log(Logger.java:472)
        at java.util.logging.Logger.doLog(Logger.java:494)
        at java.util.logging.Logger.log(Logger.java:558)
        at org.netbeans.modules.php.editor.nav.SemiAttribute.semiAttribute(SemiAttribute.java:696)
        at org.netbeans.modules.php.editor.nav.OccurrencesFinderImpl.compute(OccurrencesFinderImpl.java:112)
        at org.netbeans.modules.php.editor.nav.OccurrencesFinderImpl.run(OccurrencesFinderImpl.java:104)
        at org.netbeans.modules.php.editor.nav.OccurrencesFinderImpl.run(OccurrencesFinderImpl.java:86)
        at org.netbeans.modules.gsfret.editor.semantic.MarkOccurrencesHighlighter.processImpl(MarkOccurrencesHighlighter.java:173)
        at org.netbeans.modules.gsfret.editor.semantic.MarkOccurrencesHighlighter.run(MarkOccurrencesHighlighter.java:113)
        at org.netbeans.modules.gsfret.editor.semantic.MarkOccurrencesHighlighter.run(MarkOccurrencesHighlighter.java:80)
        at org.netbeans.napi.gsfret.source.Source$CompilationJob.run(Source.java:1374)
        at java.util.concurrent.Executors$RunnableAdapter.call(Executors.java:441)
        at java.util.concurrent.FutureTask$Sync.innerRun(FutureTask.java:303)
        at java.util.concurrent.FutureTask.run(FutureTask.java:138)
        at java.util.concurrent.ThreadPoolExecutor$Worker.runTask(ThreadPoolExecutor.java:885)
        at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:907)
        at java.lang.Thread.run(Thread.java:619)