Infinite loop in java.util.HashMap

Question

I have some Vaadin code blocking very often here, and I have no idea what the problem can be:

Thread 7892: (state = IN_JAVA)
 - java.util.HashMap.getEntry(java.lang.Object) @bci=61, line=349 (Compiled frame; information may be imprecise)
 - java.util.HashMap.containsKey(java.lang.Object) @bci=2, line=335 (Compiled frame)
 - java.util.HashSet.contains(java.lang.Object) @bci=5, line=184 (Compiled frame)
 - com.vaadin.ui.Table.unregisterPropertiesAndComponents(java.util.HashSet, java.util.HashSet) @bci=85, line=1693 (Compiled frame)
 - com.vaadin.ui.Table.refreshRenderedCells() @bci=992, line=1641 (Compiled frame)
 - com.vaadin.ui.Table.valueChange(com.vaadin.data.Property$ValueChangeEvent) @bci=23, line=2897 (Compiled frame)
 - com.vaadin.data.util.IndexedContainer.firePropertyValueChange(com.vaadin.data.util.IndexedContainer$IndexedContainerProperty) @bci=140, line=553 (Compiled frame)
 - com.vaadin.data.util.IndexedContainer.access$1000(com.vaadin.data.util.IndexedContainer, com.vaadin.data.util.IndexedContainer$IndexedContainerProperty) @bci=2, line=64 (Compiled frame)
 - com.vaadin.data.util.IndexedContainer$IndexedContainerProperty.setValue(java.lang.Object) @bci=202, line=915 (Compiled frame)
 - com.aimprosoft.wavilon.backgroundthreads.ChangeCdrThread.insertNewPersonIntoTable(com.aimprosoft.wavilon.model.Person, com.vaadin.ui.HorizontalLayout, com.aimprosoft.wavilon.ui.menuitems.CallContent, com.vaadin.ui.Table) @bci=924, line=208 (Interpreted frame)
 - com.aimprosoft.wavilon.backgroundthreads.ChangeCdrThread$RepaintTableThread.run() @bci=622, line=446 (Compiled frame)

Can somebody suggest any way to further debug this issue? The problem happens very rarely, and it is quite difficult to reproduce.

Answer 1

So what you are actually seeing here is a thread going into an infinite loop evaluating e = e.next

In essence

e.next == e

This occurs when you are putting into a HashMap by multiple threads during a table restructure.

Take a look at this link for more information

A Beautiful Race Condition

To solve this either use a Collections.synchronizedMap or ConcurrentHashMap. I suggest the latter.