RFR : 7144488 StackOverflowError occurres on list via Collections.synchronizedList(List)

David Holmes david.holmes at oracle.com
Thu Feb 23 02:44:57 UTC 2012

On 23/02/2012 12:22 AM, Alan Bateman wrote:
> On 22/02/2012 13:25, Seán Coffey wrote:
>> Bug recently reported. We enter infinite recursion on a boundary case
>> for Collections.synchronizedList.remove(..)
>> Fix is a simple equals check in class method before delegating the call.
>> bug : http://bugs.sun.com/bugdatabase/view_bug.do?bug_id=7144488
>> webrev : http://cr.openjdk.java.net/~coffeys/webrev.7144488/
> Sean - the fix looks okay to me but I assume there are other cases, like
> with SynchronizedSet and hashCode for example. I don't know if they are
> all fixable, at least not the hashCode cases.

All of the SynchronizedX.equals methods should be fixed ie 
SynchronizedSet, SynchronizedList and SynchronizedMap. It should always 
be valid to ask if a.equals(a). The idiomatic form used elsewhere 
(CheckedXXX) is:

public boolean equals(Object o)  { return o == this || list.equals(o); }

I'm not a fan of collections containing themselves, but I think it is 
simple to fix contains(o)/contains[Key]|[Value](o) and remove(o) in a 
similar way. Though none of the wrapped collections currently handle 
that case, so I'm okay with not addressing this part.

I don't see the recursion potential in hashCode() in the wrappers.


> -Alan.

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