FULL PRODUCT VERSION :
java version "1.6.0_29"
Java(TM) SE Runtime Environment (build 1.6.0_29-b11)
Java HotSpot(TM) 64-Bit Server VM (build 20.4-b02, mixed mode)

ADDITIONAL OS VERSION INFORMATION :
Microsoft Windows [Version 6.1.7601]

A DESCRIPTION OF THE PROBLEM :
StackOverflowError occurres in the following code:

import java.util.ArrayList;
import java.util.Collections;
import java.util.List;

public class Test {
    public static void main(String[] args) {
        List list = Collections.synchronizedList(new ArrayList());
        list.add(list);
        list.remove(list);
    }
}

Because ArrayList#remove(Object) is:

    public boolean remove(Object o) {
        if (o == null) {
            for (int index = 0; index < size; index++)
                if (elementData[index] == null) {
                    fastRemove(index);
                    return true;
                }
        } else {
            for (int index = 0; index < size; index++)
                if (o.equals(elementData[index])) { // call equals
                    fastRemove(index);
                    return true;
                }
        }
        return false;
    }

Collections$SynchronizedList#equals(Object) is:

        public boolean equals(Object o) {
            synchronized(mutex) {return list.equals(o);}
        }

Variable list is actual instance of List. Variable o is instance of Collections$SynchronizedList.

Called AbstractList#equals(Object) is:

    public boolean equals(Object o) {
        if (o == this)
            return true;
        if (!(o instanceof List))
            return false;

        ListIterator<E> e1 = listIterator();
        ListIterator e2 = ((List) o).listIterator();
        while(e1.hasNext() && e2.hasNext()) {
            E o1 = e1.next();
            Object o2 = e2.next();
            if (!(o1==null ? o2==null : o1.equals(o2))) // check each elements
                return false;
        }
        return !(e1.hasNext() || e2.hasNext());
    }

Variable o, o1 and o2 are instance of Collections$SynchronizedList. So this method call Collections$SynchronizedList#equals(Object).

And loop call AbstractList#equals(Object) and Collections$SynchronizedList#equals(Object).

REGRESSION. Last worked in version 6u29

STEPS TO FOLLOW TO REPRODUCE THE PROBLEM :
Compile and execute the following code:

import java.util.ArrayList;
import java.util.Collections;
import java.util.List;

public class Test {
    public static void main(String[] args) {
        List list = Collections.synchronizedList(new ArrayList());
        list.add(list);
        list.remove(list);
    }
}


EXPECTED VERSUS ACTUAL BEHAVIOR :
EXPECTED -
StackOverflowError does not occur.
ACTUAL -
StackOverflowError occurred.

ERROR MESSAGES/STACK TRACES THAT OCCUR :
Exception in thread "main" java.lang.StackOverflowError
at java.util.LinkedList.listIterator(Unknown Source)
at java.util.AbstractList.listIterator(Unknown Source)
at java.util.Collections$SynchronizedList.listIterator(Unknown Source)
at java.util.AbstractList.equals(Unknown Source)
at java.util.Collections$SynchronizedList.equals(Unknown Source)
at java.util.AbstractList.equals(Unknown Source)
at java.util.Collections$SynchronizedList.equals(Unknown Source)
at java.util.AbstractList.equals(Unknown Source)
at java.util.Collections$SynchronizedList.equals(Unknown Source)
at java.util.AbstractList.equals(Unknown Source)
at java.util.Collections$SynchronizedList.equals(Unknown Source)
at java.util.AbstractList.equals(Unknown Source)
at java.util.Collections$SynchronizedList.equals(Unknown Source)
at java.util.AbstractList.equals(Unknown Source)
at java.util.Collections$SynchronizedList.equals(Unknown Source)
at java.util.AbstractList.equals(Unknown Source)
at java.util.Collections$SynchronizedList.equals(Unknown Source)
at java.util.AbstractList.equals(Unknown Source)
at java.util.Collections$SynchronizedList.equals(Unknown Source)
at java.util.AbstractList.equals(Unknown Source)
at java.util.Collections$SynchronizedList.equals(Unknown Source)
at java.util.AbstractList.equals(Unknown Source)
at java.util.Collections$SynchronizedList.equals(Unknown Source)
at java.util.AbstractList.equals(Unknown Source)
at java.util.Collections$SynchronizedList.equals(Unknown Source)
at java.util.AbstractList.equals(Unknown Source)
at java.util.Collections$SynchronizedList.equals(Unknown Source)
at java.util.AbstractList.equals(Unknown Source)
at java.util.Collections$SynchronizedList.equals(Unknown Source)
at java.util.AbstractList.equals(Unknown Source)
at java.util.Collections$SynchronizedList.equals(Unknown Source)
at java.util.AbstractList.equals(Unknown Source)
at java.util.Collections$SynchronizedList.equals(Unknown Source)
at java.util.AbstractList.equals(Unknown Source)
at java.util.Collections$SynchronizedList.equals(Unknown Source)
at java.util.AbstractList.equals(Unknown Source)
at java.util.Collections$SynchronizedList.equals(Unknown Source)
at java.util.AbstractList.equals(Unknown Source)
at java.util.Collections$SynchronizedList.equals(Unknown Source)
at java.util.AbstractList.equals(Unknown Source)
at java.util.Collections$SynchronizedList.equals(Unknown Source)
at java.util.AbstractList.equals(Unknown Source)
at java.util.Collections$SynchronizedList.equals(Unknown Source)
at java.util.AbstractList.equals(Unknown Source)
at java.util.Collections$SynchronizedList.equals(Unknown Source)
at java.util.AbstractList.equals(Unknown Source)
at java.util.Collections$SynchronizedList.equals(Unknown Source)
at java.util.AbstractList.equals(Unknown Source)
at java.util.Collections$SynchronizedList.equals(Unknown Source)
at java.util.AbstractList.equals(Unknown Source)
at java.util.Collections$SynchronizedList.equals(Unknown Source)
at java.util.AbstractList.equals(Unknown Source)
at java.util.Collections$SynchronizedList.equals(Unknown Source)
at java.util.AbstractList.equals(Unknown Source)
at java.util.Collections$SynchronizedList.equals(Unknown Source)
at java.util.AbstractList.equals(Unknown Source)
at java.util.Collections$SynchronizedList.equals(Unknown Source)
at java.util.AbstractList.equals(Unknown Source)
at java.util.Collections$SynchronizedList.equals(Unknown Source)
at java.util.AbstractList.equals(Unknown Source)
at java.util.Collections$SynchronizedList.equals(Unknown Source)
at java.util.AbstractList.equals(Unknown Source)
at java.util.Collections$SynchronizedList.equals(Unknown Source)
at java.util.AbstractList.equals(Unknown Source)
at java.util.Collections$SynchronizedList.equals(Unknown Source)
at java.util.AbstractList.equals(Unknown Source)
at java.util.Collections$SynchronizedList.equals(Unknown Source)
at java.util.AbstractList.equals(Unknown Source)
at java.util.Collections$SynchronizedList.equals(Unknown Source)
at java.util.AbstractList.equals(Unknown Source)
at java.util.Collections$SynchronizedList.equals(Unknown Source)
at java.util.AbstractList.equals(Unknown Source)
at java.util.Collections$SynchronizedList.equals(Unknown Source)
at java.util.AbstractList.equals(Unknown Source)
at java.util.Collections$SynchronizedList.equals(Unknown Source)
at java.util.AbstractList.equals(Unknown Source)
at java.util.Collections$SynchronizedList.equals(Unknown Source)
at java.util.AbstractList.equals(Unknown Source)
at java.util.Collections$SynchronizedList.equals(Unknown Source)
at java.util.AbstractList.equals(Unknown Source)
at java.util.Collections$SynchronizedList.equals(Unknown Source)
at java.util.AbstractList.equals(Unknown Source)
at java.util.Collections$SynchronizedList.equals(Unknown Source)
at java.util.AbstractList.equals(Unknown Source)
at java.util.Collections$SynchronizedList.equals(Unknown Source)
at java.util.AbstractList.equals(Unknown Source)
at java.util.Collections$SynchronizedList.equals(Unknown Source)
at java.util.AbstractList.equals(Unknown Source)
at java.util.Collections$SynchronizedList.equals(Unknown Source)
at java.util.AbstractList.equals(Unknown Source)
at java.util.Collections$SynchronizedList.equals(Unknown Source)
at java.util.AbstractList.equals(Unknown Source)
at java.util.Collections$SynchronizedList.equals(Unknown Source)
at java.util.AbstractList.equals(Unknown Source)
at java.util.Collections$SynchronizedList.equals(Unknown Source)
at java.util.AbstractList.equals(Unknown Source)
at java.util.Collections$SynchronizedList.equals(Unknown Source)
at java.util.AbstractList.equals(Unknown Source)
at java.util.Collections$SynchronizedList.equals(Unknown Source)
at java.util.AbstractList.equals(Unknown Source)
at java.util.Collections$SynchronizedList.equals(Unknown Source)
at java.util.AbstractList.equals(Unknown Source)
at java.util.Collections$SynchronizedList.equals(Unknown Source)
at java.util.AbstractList.equals(Unknown Source)
at java.util.Collections$SynchronizedList.equals(Unknown Source)
at java.util.AbstractList.equals(Unknown Source)
at java.util.Collections$SynchronizedList.equals(Unknown Source)
at java.util.AbstractList.equals(Unknown Source)
at java.util.Collections$SynchronizedList.equals(Unknown Source)
at java.util.AbstractList.equals(Unknown Source)
at java.util.Collections$SynchronizedList.equals(Unknown Source)
at java.util.AbstractList.equals(Unknown Source)
at java.util.Collections$SynchronizedList.equals(Unknown Source)
at java.util.AbstractList.equals(Unknown Source)
at java.util.Collections$SynchronizedList.equals(Unknown Source)
at java.util.AbstractList.equals(Unknown Source)
at java.util.Collections$SynchronizedList.equals(Unknown Source)
at java.util.AbstractList.equals(Unknown Source)
at java.util.Collections$SynchronizedList.equals(Unknown Source)
at java.util.AbstractList.equals(Unknown Source)
at java.util.Collections$SynchronizedList.equals(Unknown Source)
at java.util.AbstractList.equals(Unknown Source)
at java.util.Collections$SynchronizedList.equals(Unknown Source)
at java.util.AbstractList.equals(Unknown Source)
at java.util.Collections$SynchronizedList.equals(Unknown Source)
at java.util.AbstractList.equals(Unknown Source)
at java.util.Collections$SynchronizedList.equals(Unknown Source)
at java.util.AbstractList.equals(Unknown Source)
at java.util.Collections$SynchronizedList.equals(Unknown Source)
at java.util.AbstractList.equals(Unknown Source)
at java.util.Collections$SynchronizedList.equals(Unknown Source)
at java.util.AbstractList.equals(Unknown Source)
at java.util.Collections$SynchronizedList.equals(Unknown Source)
at java.util.AbstractList.equals(Unknown Source)
at java.util.Collections$SynchronizedList.equals(Unknown Source)
at java.util.AbstractList.equals(Unknown Source)
at java.util.Collections$SynchronizedList.equals(Unknown Source)
at java.util.AbstractList.equals(Unknown Source)
at java.util.Collections$SynchronizedList.equals(Unknown Source)
at java.util.AbstractList.equals(Unknown Source)
at java.util.Collections$SynchronizedList.equals(Unknown Source)
at java.util.AbstractList.equals(Unknown Source)
at java.util.Collections$SynchronizedList.equals(Unknown Source)
at java.util.AbstractList.equals(Unknown Source)
at java.util.Collections$SynchronizedList.equals(Unknown Source)
at java.util.AbstractList.equals(Unknown Source)
at java.util.Collections$SynchronizedList.equals(Unknown Source)
at java.util.AbstractList.equals(Unknown Source)
at java.util.Collections$SynchronizedList.equals(Unknown Source)
at java.util.AbstractList.equals(Unknown Source)
at java.util.Collections$SynchronizedList.equals(Unknown Source)
at java.util.AbstractList.equals(Unknown Source)
at java.util.Collections$SynchronizedList.equals(Unknown Source)
at java.util.AbstractList.equals(Unknown Source)
at java.util.Collections$SynchronizedList.equals(Unknown Source)
at java.util.AbstractList.equals(Unknown Source)
at java.util.Collections$SynchronizedList.equals(Unknown Source)
at java.util.AbstractList.equals(Unknown Source)
at java.util.Collections$SynchronizedList.equals(Unknown Source)
at java.util.AbstractList.equals(Unknown Source)
at java.util.Collections$SynchronizedList.equals(Unknown Source)
at java.util.AbstractList.equals(Unknown Source)
at java.util.Collections$SynchronizedList.equals(Unknown Source)
at java.util.AbstractList.equals(Unknown Source)
at java.util.Collections$SynchronizedList.equals(Unknown Source)
at java.util.AbstractList.equals(Unknown Source)
at java.util.Collections$SynchronizedList.equals(Unknown Source)
at java.util.AbstractList.equals(Unknown Source)
at java.util.Collections$SynchronizedList.equals(Unknown Source)
at java.util.AbstractList.equals(Unknown Source)
at java.util.Collections$SynchronizedList.equals(Unknown Source)
at java.util.AbstractList.equals(Unknown Source)
at java.util.Collections$SynchronizedList.equals(Unknown Source)
at java.util.AbstractList.equals(Unknown Source)
at java.util.Collections$SynchronizedList.equals(Unknown Source)
at java.util.AbstractList.equals(Unknown Source)
at java.util.Collections$SynchronizedList.equals(Unknown Source)
at java.util.AbstractList.equals(Unknown Source)
at java.util.Collections$SynchronizedList.equals(Unknown Source)
at java.util.AbstractList.equals(Unknown Source)
at java.util.Collections$SynchronizedList.equals(Unknown Source)
at java.util.AbstractList.equals(Unknown Source)
at java.util.Collections$SynchronizedList.equals(Unknown Source)
at java.util.AbstractList.equals(Unknown Source)
at java.util.Collections$SynchronizedList.equals(Unknown Source)
at java.util.AbstractList.equals(Unknown Source)
at java.util.Collections$SynchronizedList.equals(Unknown Source)
at java.util.AbstractList.equals(Unknown Source)
at java.util.Collections$SynchronizedList.equals(Unknown Source)
at java.util.AbstractList.equals(Unknown Source)
at java.util.Collections$SynchronizedList.equals(Unknown Source)
at java.util.AbstractList.equals(Unknown Source)
at java.util.Collections$SynchronizedList.equals(Unknown Source)
at java.util.AbstractList.equals(Unknown Source)
at java.util.Collections$SynchronizedList.equals(Unknown Source)
at java.util.AbstractList.equals(Unknown Source)
at java.util.Collections$SynchronizedList.equals(Unknown Source)
at java.util.AbstractList.equals(Unknown Source)
at java.util.Collections$SynchronizedList.equals(Unknown Source)
at java.util.AbstractList.equals(Unknown Source)
at java.util.Collections$SynchronizedList.equals(Unknown Source)
at java.util.AbstractList.equals(Unknown Source)
at java.util.Collections$SynchronizedList.equals(Unknown Source)
at java.util.AbstractList.equals(Unknown Source)
at java.util.Collections$SynchronizedList.equals(Unknown Source)
at java.util.AbstractList.equals(Unknown Source)
at java.util.Collections$SynchronizedList.equals(Unknown Source)
at java.util.AbstractList.equals(Unknown Source)
at java.util.Collections$SynchronizedList.equals(Unknown Source)
at java.util.AbstractList.equals(Unknown Source)
at java.util.Collections$SynchronizedList.equals(Unknown Source)
at java.util.AbstractList.equals(Unknown Source)
at java.util.Collections$SynchronizedList.equals(Unknown Source)
at java.util.AbstractList.equals(Unknown Source)
at java.util.Collections$SynchronizedList.equals(Unknown Source)
at java.util.AbstractList.equals(Unknown Source)
at java.util.Collections$SynchronizedList.equals(Unknown Source)
at java.util.AbstractList.equals(Unknown Source)
at java.util.Collections$SynchronizedList.equals(Unknown Source)
at java.util.AbstractList.equals(Unknown Source)
at java.util.Collections$SynchronizedList.equals(Unknown Source)
at java.util.AbstractList.equals(Unknown Source)
at java.util.Collections$SynchronizedList.equals(Unknown Source)
at java.util.AbstractList.equals(Unknown Source)
at java.util.Collections$SynchronizedList.equals(Unknown Source)
at java.util.AbstractList.equals(Unknown Source)
at java.util.Collections$SynchronizedList.equals(Unknown Sour


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