I am not against the thoughts here. TaskManager has a very important
roll that has specific needs. It is used to dispatch inbound calls
amongst other things. It is essential that it never fail to create a
thread to handle an inbound call. Without this behavior there is a
chance for distributed deadlock.
The key clause in TPE is that it says the extra threads are not
created until the queue is full. That is another form of "maximum".
If it has a documented behavior that has no maximum, then I am okay
with using it. I have just never seen it behave correctly based on
what I have experienced and so I am concerned about the maximum thread
issue.
There are of course many types of applications that can use a ceiling
on maximum threads to throttle things. But if you look at some of the
bug reports and discussions on the concurrency-interest list, there
are cases of this behavior popping up in the fork-join pool stuff too,
where the complexity of hoe work is divided and distributed creates
problems.
Gregg Wonderly
Sent from my iPhone
On Jun 5, 2010, at 8:25 AM, Dennis Reedy <[email protected]> wrote:
On Jun 5, 2010, at 609AM, Patrick Wright wrote:
One point I'd like to raise about using java.util.concurrent and TPE:
I think that over the long term, it makes sense to (re)use existing
utilities which are being maintained by domain experts rather than
custom utilities you've written yourself. The concurrent libraries
available since Java 5 were written and maintained by people widely
recognized to be very, very good at a very hard problem. That doesn't
mean they, or the library, is perfect, just that there is value in
building on their work and letting them take care of the bugs and
optimizations over time. The downside would be that if a River user
was stuck with, say, Java 5, they couldn't take advantage of bugfixes
or improvements in Java 6. On the other hand, that's true of the
entire JDK.
The max threads issue seems to me a non-issue. A JVM can allocate
only
so many native threads before it runs out of OS resources; that's a
hard limit. You can set a max of Integer.MAX_VALUE but your VM would
die long, long before it reached that.
For me this is more of design policy decision. Re-use, intelligently
and selectively, where possible, to reduce your project's workload.
Patrick
+1
