Kris Schneider wrote:
I work with Dan and here's the rest of the story:
We ran into severe enough problems using flowscript on WebLogic 8.1
(Rhino issues, really), that we had to switch to Java flow. As we've
gone down that road, we've come to the realization that all of our
continuations seem to have a time to live of ten minutes, regardless
of how we configure the <continuations-manager> element in
cocoon.xconf. As it turns out, JavaInterpreter uses a hard-coded,
non-configurable value of 600000 for continuation time to live. Have
we missed anything with regard to being able to configure that aspect
of JavaInterpreter?
One thing: time-to-live in ContinuationsManagerImpl is ONLY used when
the WebContinuation does not provide it's own one (but that's probably
something you figured already). So this is an issue with
JavaInterpreter. Torsten could you comment?
During our investigation of the time to live issue, we also came
across some concurrency issues with ContinuationsManagerImpl. This
class uses the following to store/manage continuations:
protected SortedSet expirations =
Collections.synchronizedSortedSet(new TreeSet());
There are a couple of places where that collection is iterated by doing:
Iterator i = expirations.iterator();
while (...) {
// use i
}
This really should be changed to something like this:
synchronized(expirations) {
Iterator i = expirations.iterator();
while (...) {
// use i
}
}
This advice is contained within the Javadoc for
Collections.synchronizedSortedSet.
http://java.sun.com/j2se/1.3/docs/api/java/util/Collections.html#synchronizedSortedSet(java.util.SortedSet)
Some other references worth reading:
http://java.sun.com/j2se/1.3/docs/api/java/util/Iterator.html#remove()
http://java.sun.com/j2se/1.3/docs/api/java/util/ConcurrentModificationException.html
Having said that, it seems like someone would have been screaming by
now about continuation management being horribly broken. So, is Java
flow just not being used, or used under such low levels of concurrency
that the problem hasn't surfaced yet? Or is our analysis of the code
just incorrect?
Strange. I have already made a mistake once - a
ConcurrentModificationException popped on the user list only few days
later :). I'm not ruling out the code might be wrong though.
Java flow does not matter here. Any flow implementation uses the same
continuations manager.
--
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
