How to timeout a task using the ThreadpoolExecutor?

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Hi all.

I'm wonder what are the possible approaches to handle timeout of a task that was submitted to an executor ThreadPoolExecutor.
I know I can timeout while getting the result like so future.result(timeout=x). But I don't understand how can I timeout a task, in a non-blocking way, when I'm on "fire and forget" mode.

Example:

# Send the task to the pool
future = self.executor.submit(mytask, arg)
future.add_done_callback(...)

# By this time, I can `get` the result with timeout
future.result(timeout=xxx)

# Send the task to the pool
future = self.executor.submit(mytask, arg)
future.add_done_callback(...)

# By this time, I can `get` the result with timeout
future.result(timeout=xxx)

But if I call the result, I'll block, and I won't be able to send more tasks to the pool.
What I'm trying to do is something like:

# Notice the timeout would be defined when sending the task, and not when getting the result
future = self.executor.submit(mytask, arg, timeout=10)

# Assign the callback normally
future.add_done_callback(...)

# Here, I don't care about the result, I want to be able to submit another task
?

I though about opening a new "maintenance" thread, that only waits for the results of all tasks, but again, wouldn't I be blocking for each call?
Say I have 100 tasks periodically being sent to the executor, each just time.sleep(10). How can I make sure that none of those tasks pass 10 seconds?
If it helps, the context is a task queue, hence the "fire and forget" logic.

Any help/suggestion is welcome.
Thanks a lot!