🚀 go-pugleaf

>         while (localStack.keySet().iterator().hasNext()) {
>           String fileName=(String)localStack.keySet().iterator().next();
>         }
>
> Now, what would happen if somebody else, out of this thread, adds/removes
a
> few lines in localStack while this loop is running. LocalStack is HashMap.

HashMap is not synchronized, so the answer is nothing good (hard to predict,
but without synchronizing access to it, deadlocks (for example) are
definately on the menu). You've got a number of options for getting round
this
    1)As suggested in the Javadoc for HashMap, use java.util.Collections to
obtain a synchronized refernece to localStack *which is used for every call
in every thread* (otherwise there's no point doing it...).

    2)To acheieve the same result, wrap every call to localStack in
synchonized(){ } blocks.

FYI, check out
http://java.sun.com/docs/books/jls/second_edition/html/memory.doc.html#28460

hth
Owen Green