272 lines
7.9 KiB
Python
272 lines
7.9 KiB
Python
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"""
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* Experimental *
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Like the map function, but can use a pool of threads.
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Really easy to use threads. eg. tmap(f, alist)
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If you know how to use the map function, you can use threads.
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"""
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__author__ = "Rene Dudfield"
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__version__ = "0.3.0"
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__license__ = "Python license"
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from queue import Queue, Empty
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import threading
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Thread = threading.Thread
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STOP = object()
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FINISH = object()
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# DONE_ONE = object()
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# DONE_TWO = object()
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# a default worker queue.
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_wq = None
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# if we are using threads or not. This is the number of workers.
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_use_workers = 0
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# Set this to the maximum for the amount of Cores/CPUs
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# Note, that the tests early out.
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# So it should only test the best number of workers +2
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MAX_WORKERS_TO_TEST = 64
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def init(number_of_workers=0):
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"""Does a little test to see if threading is worth it.
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Sets up a global worker queue if it's worth it.
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Calling init() is not required, but is generally better to do.
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"""
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global _wq, _use_workers
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if number_of_workers:
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_use_workers = number_of_workers
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else:
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_use_workers = benchmark_workers()
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# if it is best to use zero workers, then use that.
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_wq = WorkerQueue(_use_workers)
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def quit():
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"""cleans up everything."""
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global _wq, _use_workers
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_wq.stop()
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_wq = None
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_use_workers = False
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def benchmark_workers(a_bench_func=None, the_data=None):
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"""does a little test to see if workers are at all faster.
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Returns the number of workers which works best.
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Takes a little bit of time to run, so you should only really call
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it once.
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You can pass in benchmark data, and functions if you want.
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a_bench_func - f(data)
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the_data - data to work on.
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"""
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# TODO: try and make this scale better with slower/faster cpus.
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# first find some variables so that using 0 workers takes about 1.0 seconds.
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# then go from there.
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# note, this will only work with pygame 1.8rc3+
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# replace the doit() and the_data with something that releases the GIL
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import pygame
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import pygame.transform
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import time
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if not a_bench_func:
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def doit(x):
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return pygame.transform.scale(x, (544, 576))
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else:
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doit = a_bench_func
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if not the_data:
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thedata = [pygame.Surface((155, 155), 0, 32) for x in range(10)]
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else:
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thedata = the_data
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best = time.time() + 100000000
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best_number = 0
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# last_best = -1
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for num_workers in range(0, MAX_WORKERS_TO_TEST):
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wq = WorkerQueue(num_workers)
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t1 = time.time()
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for _ in range(20):
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print(f"active count:{threading.active_count()}")
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tmap(doit, thedata, worker_queue=wq)
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t2 = time.time()
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wq.stop()
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total_time = t2 - t1
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print(f"total time num_workers:{num_workers}: time:{total_time}:")
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if total_time < best:
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# last_best = best_number
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best_number = num_workers
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best = total_time
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if num_workers - best_number > 1:
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# We tried to add more, but it didn't like it.
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# so we stop with testing at this number.
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break
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return best_number
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class WorkerQueue:
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def __init__(self, num_workers=20):
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self.queue = Queue()
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self.pool = []
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self._setup_workers(num_workers)
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def _setup_workers(self, num_workers):
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"""Sets up the worker threads
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NOTE: undefined behaviour if you call this again.
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"""
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self.pool = []
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for _ in range(num_workers):
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self.pool.append(Thread(target=self.threadloop))
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for a_thread in self.pool:
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a_thread.setDaemon(True)
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a_thread.start()
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def do(self, f, *args, **kwArgs):
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"""puts a function on a queue for running later."""
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self.queue.put((f, args, kwArgs))
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def stop(self):
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"""Stops the WorkerQueue, waits for all of the threads to finish up."""
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self.queue.put(STOP)
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for thread in self.pool:
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thread.join()
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def threadloop(self): # , finish=False):
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"""Loops until all of the tasks are finished."""
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while True:
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args = self.queue.get()
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if args is STOP:
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self.queue.put(STOP)
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self.queue.task_done()
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break
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try:
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args[0](*args[1], **args[2])
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finally:
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# clean up the queue, raise the exception.
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self.queue.task_done()
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# raise
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def wait(self):
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"""waits until all tasks are complete."""
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self.queue.join()
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class FuncResult:
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"""Used for wrapping up a function call so that the results are stored
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inside the instances result attribute.
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"""
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def __init__(self, f, callback=None, errback=None):
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"""f - is the function we that we call
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callback(result) - this is called when the function(f) returns
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errback(exception) - this is called when the function(f) raises
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an exception.
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"""
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self.f = f
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self.exception = None
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self.result = None
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self.callback = callback
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self.errback = errback
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def __call__(self, *args, **kwargs):
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# we try to call the function here. If it fails we store the exception.
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try:
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self.result = self.f(*args, **kwargs)
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if self.callback:
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self.callback(self.result)
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except Exception as e:
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self.exception = e
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if self.errback:
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self.errback(self.exception)
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def tmap(f, seq_args, num_workers=20, worker_queue=None, wait=True, stop_on_error=True):
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"""like map, but uses a thread pool to execute.
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num_workers - the number of worker threads that will be used. If pool
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is passed in, then the num_workers arg is ignored.
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worker_queue - you can optionally pass in an existing WorkerQueue.
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wait - True means that the results are returned when everything is finished.
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False means that we return the [worker_queue, results] right away instead.
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results, is returned as a list of FuncResult instances.
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stop_on_error -
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"""
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if worker_queue:
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wq = worker_queue
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else:
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# see if we have a global queue to work with.
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if _wq:
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wq = _wq
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else:
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if num_workers == 0:
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return map(f, seq_args)
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wq = WorkerQueue(num_workers)
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# we short cut it here if the number of workers is 0.
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# normal map should be faster in this case.
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if len(wq.pool) == 0:
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return map(f, seq_args)
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# print("queue size:%s" % wq.queue.qsize())
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# TODO: divide the data (seq_args) into even chunks and
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# then pass each thread a map(f, equal_part(seq_args))
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# That way there should be less locking, and overhead.
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results = []
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for sa in seq_args:
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results.append(FuncResult(f))
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wq.do(results[-1], sa)
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# wq.stop()
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if wait:
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# print("wait")
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wq.wait()
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# print("after wait")
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# print("queue size:%s" % wq.queue.qsize())
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if wq.queue.qsize():
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raise RuntimeError("buggy threadmap")
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# if we created a worker queue, we need to stop it.
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if not worker_queue and not _wq:
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# print("stopping")
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wq.stop()
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if wq.queue.qsize():
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um = wq.queue.get()
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if not um is STOP:
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raise RuntimeError("buggy threadmap")
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# see if there were any errors. If so raise the first one. This matches map behaviour.
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# TODO: the traceback doesn't show up nicely.
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# NOTE: TODO: we might want to return the results anyway? This should be an option.
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if stop_on_error:
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error_ones = list(filter(lambda x: x.exception, results))
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if error_ones:
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raise error_ones[0].exception
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return map(lambda x: x.result, results)
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return [wq, results]
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