Checking up on a `concurrent.futures.ThreadPoolExecutor`
I've got a live concurrent.futures.ThreadPoolExecutor . I want to check its status. I want to know how many threads there are, how many are handling tasks and which tasks, how many are free, and which tasks are in the queue. How can I find out these things?
There is some visibility into the Pool, and the pending workitem queue. To find out what's available, print poolx.__dict__ to see the structure. Read the ThreadPool code, it's pretty good: concurrent.futures.thread
The following creates a pool with one thread. It then creates two jobs: one sleeps for 3 seconds, the other immediately returns. The pool's number of pending work items is then printed.
Following that, we print out items from the work queue. In this case, a thread is already executing the time.sleep(3) function, so that's not in the queue. The function sleep with args [0] and kwargs {} is printed, because that's the next work item for the pool to run.
Kudos to @dano for the nondestructive queue insight, and @abarnert.
source
import concurrent.futures, time
poolx = concurrent.futures.ThreadPoolExecutor(max_workers=1)
poolx.submit(time.sleep, 3)
poolx.submit(time.sleep, 0) # very fast
print('pending:', poolx._work_queue.qsize(), 'jobs')
print('threads:', len(poolx._threads))
print()
# TODO: make thread safe; work on copy of queue?
print('Estimated Pending Work Queue:')
for num,item in enumerate(poolx._work_queue.queue):
print('{}t{}t{}t{}'.format(
num+1, item.fn, item.args, item.kwargs,
))
poolx.shutdown(wait=False)
output
pending: 1 jobs
threads: 1
Pending Work Queue:
1 <built-in function sleep> (0,) {}
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