How one goes on testing a threaded program, apart from doing a few

successful runs and crossing his fingers that it at least follows the

'correct 99.9999% of the time' rule ? I've written a stripped-down

python version of Doug Lea's PooledExecutor thread pool class

(

http://gee.cs.oswego.edu/dl/classes/...Executor.html),

I ran a few simple examples that seem to work as expected, but I still

wouldn't bet any serious amount on its correctness. Any general, or

specific to this problem, tesing guidelines ?

As for the 'stripped-down version', it refers to the lack of shutting

down facilities. These are based on interrupting a thread and AFAIK

this is not possible in python, is it ?

On the other hand, in addition to the main execute(command) method of

the original PooledExecutor, I added a new dispatch(callables)

generator method. This takes an iterable over zero-argument callables,

it dispatches them to separate threads according to the thread pool's

configuration (minPoolSize,maxPoolSize,etc.), collects the results in a

queue as they are computed and yields them back to the caller. Since

the order of the computed results is not in general the same with the

order of the input, the yielded items are tuples (i,result), where i is

the index of the respective callable that returned this result. As a

toy example:

from math import sqrt

from itertools import count

tasks = (lambda x=n: sqrt(x) for n in count())

pool = PooledExecutor(minPoolSize=4)

for n,s in pool.dispatch(tasks):

print "The square root of %d is %s" % (n,s)

George