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POConcurrentModificationException in single Threaded unmodifiableList
 

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  1. POConcurrentModificationException in single Threaded unmodifiableList
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    <p>I have a single threaded application that iterates over a huge tree structure where children are stored in a list. The iterators always operate on an unmodifiable list:</p> <pre><code>public List&lt;HierarchyNode&gt; getChildren() { return Collections.unmodifiableList(children); } </code></pre> <p>Still I get an ConcurrentModificationException at some point, which I thought impossible in an unmodifiable List? The iteration is done using a visitor... any ideas how this is possible?</p> <p>EDIT: The only one who can modify this list is the Constructor of the class holding the list:</p> <pre><code>private final List&lt;HierarchyNode&gt; children; </code></pre> <p>Maybe this is related to the fact that the memory usage of thetree is fairly large (>4GB)?</p> <p>Trace:</p> <pre><code>Testcase: testParserSingleFile(General.NetlistBuilder): Caused an ERROR null java.util.ConcurrentModificationException at java.util.ArrayList$Itr.checkForComodification(ArrayList.java:819) at java.util.ArrayList$Itr.next(ArrayList.java:791) at java.util.Collections$UnmodifiableCollection$1.next(Collections.java:1067) at com.bevm.hierarchy.HierarchyNodeVisitorImplementation.visitArchitectureNode(HierarchyNodeVisitorImplementation.java:20) at com.bevm.semantics.netlist.NetlistBuilder.visitArchitectureNode(NetlistBuilder.java:40) at com.bevm.hierarchy.ArchitectureNode.accept(ArchitectureNode.java:25) at com.bevm.hierarchy.HierarchyNodeVisitorImplementation.visitEntityNode(HierarchyNodeVisitorImplementation.java:33) at com.bevm.semantics.netlist.NetlistBuilder.visitEntityNode(NetlistBuilder.java:33) at com.bevm.hierarchy.EntityNode.accept(EntityNode.java:33) at com.bevm.hierarchy.HierarchyNodeVisitorImplementation.visitComponentNode(HierarchyNodeVisitorImplementation.java:27) at com.bevm.hierarchy.ComponentNode.accept(ComponentNode.java:25) at com.bevm.hierarchy.HierarchyNodeVisitorImplementation.visitInstanceNode(HierarchyNodeVisitorImplementation.java:45) at com.bevm.semantics.netlist.NetlistBuilder.visitInstanceNode(NetlistBuilder.java:85) at com.bevm.hierarchy.InstanceNode.accept(InstanceNode.java:89) at com.bevm.hierarchy.HierarchyNodeVisitorImplementation.visitArchitectureNode(HierarchyNodeVisitorImplementation.java:21) at com.bevm.semantics.netlist.NetlistBuilder.visitArchitectureNode(NetlistBuilder.java:40) at com.bevm.hierarchy.ArchitectureNode.accept(ArchitectureNode.java:25) at com.bevm.hierarchy.HierarchyNodeVisitorImplementation.visitEntityNode(HierarchyNodeVisitorImplementation.java:33) at com.bevm.semantics.netlist.NetlistBuilder.visitEntityNode(NetlistBuilder.java:33) at com.bevm.hierarchy.EntityNode.accept(EntityNode.java:33) at com.bevm.hierarchy.HierarchyNodeVisitorImplementation.visitComponentNode(HierarchyNodeVisitorImplementation.java:27) at com.bevm.hierarchy.ComponentNode.accept(ComponentNode.java:25) at com.bevm.hierarchy.HierarchyNodeVisitorImplementation.visitInstanceNode(HierarchyNodeVisitorImplementation.java:45) at com.bevm.semantics.netlist.NetlistBuilder.visitInstanceNode(NetlistBuilder.java:85) at com.bevm.hierarchy.InstanceNode.accept(InstanceNode.java:89) at com.bevm.hierarchy.HierarchyNodeVisitorImplementation.visitArchitectureNode(HierarchyNodeVisitorImplementation.java:21) at com.bevm.semantics.netlist.NetlistBuilder.visitArchitectureNode(NetlistBuilder.java:40) at com.bevm.hierarchy.ArchitectureNode.accept(ArchitectureNode.java:25) at com.bevm.hierarchy.HierarchyNodeVisitorImplementation.visitEntityNode(HierarchyNodeVisitorImplementation.java:33) at com.bevm.semantics.netlist.NetlistBuilder.visitEntityNode(NetlistBuilder.java:33) at com.bevm.hierarchy.EntityNode.accept(EntityNode.java:33) at com.bevm.hierarchy.HierarchyNodeVisitorImplementation.visitComponentNode(HierarchyNodeVisitorImplementation.java:27) at com.bevm.hierarchy.ComponentNode.accept(ComponentNode.java:25) at com.bevm.hierarchy.HierarchyNodeVisitorImplementation.visitInstanceNode(HierarchyNodeVisitorImplementation.java:45) at com.bevm.semantics.netlist.NetlistBuilder.visitInstanceNode(NetlistBuilder.java:85) at com.bevm.hierarchy.InstanceNode.accept(InstanceNode.java:89) at com.bevm.hierarchy.HierarchyNodeVisitorImplementation.visitGenerateNode(HierarchyNodeVisitorImplementation.java:39) at com.bevm.semantics.netlist.NetlistBuilder.visitGenerateNode(NetlistBuilder.java:79) at com.bevm.hierarchy.GenerateNode.accept(GenerateNode.java:27) at com.bevm.hierarchy.HierarchyNodeVisitorImplementation.visitArchitectureNode(HierarchyNodeVisitorImplementation.java:21) at com.bevm.semantics.netlist.NetlistBuilder.visitArchitectureNode(NetlistBuilder.java:40) at com.bevm.hierarchy.ArchitectureNode.accept(ArchitectureNode.java:25) at com.bevm.hierarchy.HierarchyNodeVisitorImplementation.visitEntityNode(HierarchyNodeVisitorImplementation.java:33) at com.bevm.semantics.netlist.NetlistBuilder.visitEntityNode(NetlistBuilder.java:33) at com.bevm.hierarchy.EntityNode.accept(EntityNode.java:33) at com.beckhoff.vmagic.hierarchy.HierarchyNodeVisitorImplementation.visit(HierarchyNodeVisitorImplementation.java:15) at General.NetlistBuilder.testParserSingleFile(NetlistBuilder.java:125) </code></pre>
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    1. USBennyBarns
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    1. This table or related slice is empty.
    1. This table or related slice is empty.
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      1. POConcurrentModificationException in single Threaded unmodifiableList
      1. USBhavik Ambani
      1. VTFavorite
    2. VO
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      1. POConcurrentModificationException in single Threaded unmodifiableList
      1. This table or related slice is empty.
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    1. COI have faced the same issue earlier.
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      1. POConcurrentModificationException in single Threaded unmodifiableList
      1. USBhavik Ambani
    2. COCan you show your iteration code?
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      1. USCAMOBAP
    3. COPlease write your complete stack trace.
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      1. POConcurrentModificationException in single Threaded unmodifiableList
      1. USBhavik Ambani
 

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