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ZdZG dd deZ G dd dZ dd Z G dd de Z G dd de Z!G dd de Z"G dd d e Z#d d Z$d d Z%d1d!d"Z&d#d$ Z'd%d& Z(d'd( Z)da*da+d)d* Z,d+d, Z-G d-d. d.ej.Z/G d/d0 d0ej0Z1e2e dS )2a- Implements ProcessPoolExecutor.
The following diagram and text describe the data-flow through the system:
|======================= In-process =====================|== Out-of-process ==|
+----------+ +----------+ +--------+ +-----------+ +---------+
| | => | Work Ids | | | | Call Q | | Process |
| | +----------+ | | +-----------+ | Pool |
| | | ... | | | | ... | +---------+
| | | 6 | => | | => | 5, call() | => | |
| | | 7 | | | | ... | | |
| Process | | ... | | Local | +-----------+ | Process |
| Pool | +----------+ | Worker | | #1..n |
| Executor | | Thread | | |
| | +----------- + | | +-----------+ | |
| | <=> | Work Items | <=> | | <= | Result Q | <= | |
| | +------------+ | | +-----------+ | |
| | | 6: call() | | | | ... | | |
| | | future | | | | 4, result | | |
| | | ... | | | | 3, except | | |
+----------+ +------------+ +--------+ +-----------+ +---------+
Executor.submit() called:
- creates a uniquely numbered _WorkItem and adds it to the "Work Items" dict
- adds the id of the _WorkItem to the "Work Ids" queue
Local worker thread:
- reads work ids from the "Work Ids" queue and looks up the corresponding
WorkItem from the "Work Items" dict: if the work item has been cancelled then
it is simply removed from the dict, otherwise it is repackaged as a
_CallItem and put in the "Call Q". New _CallItems are put in the "Call Q"
until "Call Q" is full. NOTE: the size of the "Call Q" is kept small because
calls placed in the "Call Q" can no longer be cancelled with Future.cancel().
- reads _ResultItems from "Result Q", updates the future stored in the
"Work Items" dict and deletes the dict entry
Process #1..n:
- reads _CallItems from "Call Q", executes the calls, and puts the resulting
_ResultItems in "Result Q"
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process: A list of the ctx.Process instances used as
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pending_work_items: A dict mapping work ids to _WorkItems e.g.
{5: <_WorkItem...>, 6: <_WorkItem...>, ...}
work_ids_queue: A queue.Queue of work ids e.g. Queue([5, 6, ...]).
call_queue: A ctx.Queue that will be filled with _CallItems
derived from _WorkItems for processing by the process workers.
result_queue: A ctx.SimpleQueue of _ResultItems generated by the
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thread_wakeup: A _ThreadWakeup to allow waking up the
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mp_context: A multiprocessing context to launch the workers. This
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initializer: A callable used to initialize worker processes.
initargs: A tuple of arguments to pass to the initializer.
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zProcessPoolExecutor.submitr! )timeoutrQ c s: |dk rt dt jtt|t|d|i|d}t|S )aj Returns an iterator equivalent to map(fn, iter).
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timeout: The maximum number of seconds to wait. If None, then there
is no limit on the wait time.
chunksize: If greater than one, the iterables will be chopped into
chunks of size chunksize and submitted to the process pool.
If set to one, the items in the list will be sent one at a time.
Returns:
An iterator equivalent to: map(func, *iterables) but the calls may
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Raises:
TimeoutError: If the entire result iterator could not be generated
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Exception: If fn(*args) raises for any values.
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