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Subject Re: Licensing / Source Question
Date Fri, 29 Dec 2000 06:41:33 GMT
Hi Dan,

> In the course of some work I've been doing on Tomcat, I've been
> thinking about using a Thread Pool.  There is currently a bunch of code
> doing this in both TC 3 and TC 4, but, no surprise, it's extremely
> difficult to understand and/or extend.

Well, it is a big surprise - I thought TC 4 is perfect, only TC 3 is
difficult to understand and need refactorings :-)

> Doug Lea, author of Concurrent Programming in Java, has written a set
> of concurrency utility classes, including a very nice-looking ThreadPool
> ("PooledExecutor") implementation, and some good "Channels" for
> communication between threads.  He documents these at:

I looked at the code - it's really nice. And what got me really excited
was that by using it more code could be shared and reused in 3.x and 4.x -
as long as both use a common collection of shared utilities it'll make my
life much easier ( and not only mine ).

Now, for the negative side:

- it's not JDK1.1 - but that's not a big problem, as long as the old
thread pool and modules are around for the poor souls using 1.1.
Since they use Runnable it'll be easy to use the old pools for 1.1 and the
new code for 1.2+

- do you want to check in all the code ? It isn't bad, but maybe it would
be a better idea to check in only a subset - or move the utils in a
different top-level directory. 

- maybe an idea would be to ask the author - maybe he would like to
contribute it as Apache code.

- my feeling is that as functionality it doesn't do much more than the
current thread pools - and one thing less. The interface used in TC3 pools
( ThreadPoolRunnable ) allow to maintain and pass some per/thread data, 
that allow better recycling the objects. The alternative is to use object
pools, but that may be a bit slower ( just a bit - so it's not a big
problem either).  


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