Sunbug 6934356: Vector.writeObject() synchronization risks serialization deadlock

Alan Bateman Alan.Bateman at
Tue Jan 11 13:47:06 UTC 2011

Brian Goetz wrote:
> While on the subject of serialization deadlocks in core libraries, Amy Williams and Mike Ernst did a paper (also became Amy's masters thesis) back when Mike was at MIT on static detection of deadlocks and they built a tools which found several deadlocks in the JDK collections.  Does anyone recall any bugs from this source being fixed?  
I don't have history in this area but I see her M.Sc. is online and sure 
enough, in section 6.1.1 "As an example, consider java.util.Hashtable. 
This class can be deadlocked by creating two Hashtable objects and 
adding each as an element of the other, i.e., by forming a cyclic 
relationship between the instances." and further on, "all synchronized 
Collections and combinations of such Collections (e.g., a Vector in a 
cyclic relationship with a Hashtable) can be dead- locked in a similar 
fashion". Looks like she was running with JDK 1.4 but I don't think 
legacy Hashtable or Vector have changed much since then. I see someone 
actually ran into this with j.u.Properties:
  6582568: (coll) Concurrent Hashtable.equals deadlock


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