On 5/10/05, Leszek Gawron <[EMAIL PROTECTED]> wrote:
Peter Hunsberger wrote:
On 5/10/05, Leszek Gawron <[EMAIL PROTECTED]> wrote:
Vadim Gritsenko wrote:
Leszek Gawron wrote:
Vadim Gritsenko wrote:
If you want to tinker with ContinuationsManagerImpl, take a look at: http://marc.theaimsgroup.com/?l=xml-cocoon-dev&m=111323704203839
Strange I missed that post ..
Unsynchronized access to WebContinuationsHolder from invalidateContinuations() simultaneously with write access in generateContinuation() should reliably cause ConcurrentModificationException.
I do not quite get the problem. Doesn't it cause ConcurrentModificationException now?
It should - I've not seen it though.
Other thing is how can invalidateContinuations and generateContinuation be run concurrently. invalidateContinuations is invoked only for expired sessions - how can new continuation be generated for that session?
Bad example then. Here is better one:
invalidateContinuations() gets Iterator on continuationsHolder.holder map. invalidateContinuations() calls _invalidate() _invalidate() calls disposeContinuation() disposeContinuation() modifies continuationsHolder.holder map.
After that,
invalidateContinuations() calls next() and causes ConcurrentModificationException.
Seems to me invalidateContinuations() should have while(!empty) loop instead of iterator.
Still HashMap has no interface other than iterator to get it's contents. you can either iterate through hashMap.iterator() or hashMap().keySet().iterator() - no difference, both are synced.
any ideas?
I've seen this problem with the 1.4.2_02 JDK, don't know if it exists elsewhere. The Sun docs claim syncrhonizing on the hashMap should solve the problem but it doesn't. The solution I came up with was to build an array instead of using an iterator, eg:
Object[] list = targetObjects.keySet().toArray();
Peter Hunsberger
I doubt it will work:
AbstractCollection.toArray() is in fact the implementation for HashMap.KeySet.toArray():
public Object[] toArray() { Object[] result = new Object[size()]; Iterator e = iterator(); for (int i=0; e.hasNext(); i++) result[i] = e.next(); return result; }
also uses iterator.
Building the array and then walking it is different than using the
iterator to walk the key set directly. The exception comes when you
touch an object in the key set that is accessed through the iterator. With the array, you're no longer using the iterator at the time you
touch the object. As a result you don't get the exception (not that
you should have gotten it in the first place).
I see. I'll change the code then.
I do not know how memory intensive .toArray() in production environment might be. There may be a lot of continuations to clear on session invalidation.
-- Leszek Gawron [EMAIL PROTECTED] IT Manager MobileBox sp. z o.o. +48 (61) 855 06 67 http://www.mobilebox.pl mobile: +48 (501) 720 812 fax: +48 (61) 853 29 65
