JarFileFactory has two Maps that it uses to implement caching of jar
files. Access to these maps should always be done while holding the
instance lock, as multiple threads can be simultaneously updating the maps.
The close() method was added some time after the original
implementation, and it looks like the locking was forgotten. Also, the
locking strategy assumes that JarFileFactory is a singleton. It should
be reworked to make it more robust. There is much more cleanup that can
be done here, and I intend to do it as a separate bug, so as not to
confuse the specifics of this issue.
http://cr.openjdk.java.net/~chegar/8010282/webrev.00/webrev/
-Chris.
