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- Better and faster error handling.

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This commit is contained in:
Wim Pomp
2021-03-19 20:39:38 +01:00
parent ddc0189bad
commit 5d57081713
2 changed files with 92 additions and 76 deletions
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122
parfor/__init__.py
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@@ -1,7 +1,6 @@
from __future__ import print_function
import sys
import multiprocessing
import warnings
import dill
from tqdm.auto import tqdm
from traceback import format_exc
@@ -19,6 +18,7 @@ except ImportError:
failed_rv = (lambda *args, **kwargs: None, ())
class Pickler(dill.Pickler):
""" Overload dill to ignore unpickleble parts of objects.
You probably didn't want to use these parts anyhow.
@@ -105,6 +105,7 @@ class Pickler(dill.Pickler):
except:
self.save_reduce(obj=obj, *failed_rv)
def dumps(obj, protocol=None, byref=None, fmode=None, recurse=True, **kwds):
"""pickle an object to a string"""
protocol = dill.settings['protocol'] if protocol is None else int(protocol)
@@ -114,6 +115,7 @@ def dumps(obj, protocol=None, byref=None, fmode=None, recurse=True, **kwds):
Pickler(file, protocol, **_kwds).dump(obj)
return file.getvalue()
def chunks(n, *args):
""" Yield successive n-sized chunks from lists. """
A = len(args) == 1
@@ -125,13 +127,14 @@ def chunks(n, *args):
else:
yield [a[i:i+n] for a in args]
class tqdmm(tqdm):
""" Overload tqdm to make a special version of tqdm functioning as a meter. """
def __init__(self, *args, **kwargs):
self._n = 0
self.disable = False
if not 'bar_format' in kwargs and len(args) < 16:
if 'bar_format' not in kwargs and len(args) < 16:
kwargs['bar_format'] = '{n}/{total}'
super(tqdmm, self).__init__(*args, **kwargs)
@@ -150,8 +153,9 @@ class tqdmm(tqdm):
self.n = self.total
super(tqdmm, self).__exit__(exc_type, exc_value, traceback)
def parfor(*args, **kwargs):
""" @parfor(iterator=None, args=(), kwargs={}, length=None, desc=None, bar=True, qbar=True, rP=1/3, serial=4, debug=False):
""" @parfor(iterator=None, args=(), kwargs={}, length=None, desc=None, bar=True, qbar=True, rP=1/3, serial=4):
decorator to parallize for-loops
required arguments:
@@ -169,7 +173,6 @@ def parfor(*args, **kwargs):
nP: number of workers, default: None, overrides rP if not None
number of workers will always be at least 2
serial: switch to serial if number of tasks less than serial, default: 4
debug: if an error occurs in an iteration, return the erorr instead of retrying in the main process
output: list with results from applying the decorated function to each iteration of the iterator
specified as the first argument to the function
@@ -236,12 +239,12 @@ def parfor(*args, **kwargs):
return pmap(fun, *args, **kwargs)
return decfun
class parpool(object):
""" Parallel processing with addition of iterations at any time and request of that result any time after that.
The target function and its argument can be changed at any time.
"""
def __init__(self, fun=None, args=None, kwargs=None, rP=None, nP=None, bar=None, qbar=None, terminator=None,
debug=False):
def __init__(self, fun=None, args=None, kwargs=None, rP=None, nP=None, bar=None, qbar=None, terminator=None):
""" fun, args, kwargs: target function and its arguments and keyword arguments
rP: ratio workers to cpu cores, default: 1
nP: number of workers, default, None, overrides rP if not None
@@ -256,22 +259,22 @@ class parpool(object):
self.fun = fun or (lambda x: x)
self.args = args or ()
self.kwargs = kwargs or {}
self.debug = debug
if hasattr(multiprocessing, 'get_context'):
ctx = multiprocessing.get_context('spawn')
else:
ctx = multiprocessing
self.A = ctx.Value('i', self.nP)
self.E = ctx.Event()
self.Qi = ctx.Queue(3*self.nP)
self.Qo = ctx.Queue(3*self.nP)
self.P = ctx.Pool(self.nP, self._worker(self.Qi, self.Qo, self.E, terminator, self.debug))
self.P = ctx.Pool(self.nP, self._worker(self.Qi, self.Qo, self.A, self.E, terminator))
self.is_alive = True
self.res = {}
self.handle = 0
self.handles = []
self.bar = bar
self.qbar = qbar
if not self.qbar is None:
if self.qbar is not None:
self.qbar.total = 3*self.nP
@property
@@ -310,28 +313,19 @@ class parpool(object):
def _getfromq(self):
""" Get an item from the queue and store it. """
try:
r = self.Qo.get(True, 0.02)
if r[0] is None:
self.res[r[1]] = dill.loads(r[2])
elif r[0] is False:
pfmt = warnings.formatwarning
warnings.formatwarning = lambda message, *args: '{}\n'.format(message)
warnings.warn(
'Warning, error occurred in iteration {}. The iteration will be retried and should raise a '
'debuggable error. If it doesn\'t, it\'s an error specific to parallel execution.'
.format(r[1]))
warnings.formatwarning = pfmt
fun, args, kwargs = [dill.loads(f[1]) for f in r[2][1:]]
r = (False, r[1], fun(dill.loads(r[2][0]), *args, **kwargs))
self.res[r[1]] = r[2]
err, i, res = self.Qo.get(True, 0.02)
if not err:
self.res[i] = dill.loads(res)
else:
err = dill.loads(r[2])
pfmt = warnings.formatwarning
warnings.formatwarning = lambda message, *args: '{}\n'.format(message)
warnings.warn('Warning, error occurred in iteration {}:\n{}'.format(r[1], err))
warnings.formatwarning = pfmt
self.res[r[1]] = err
if not self.bar is None:
n, fun, args, kwargs, e = [dill.loads(r) for r in res]
print('Error from process working on iteration {}:\n'.format(i))
print(e)
self.close()
print('Retrying in main thread...')
self.res[i] = fun(n, *args, **kwargs)
raise Exception('Function \'{}\' cannot be executed by parfor, amend or execute in serial.'
.format(fun.__name__))
if self.bar is not None:
self.bar.update()
self._qbar_update()
except multiprocessing.queues.Empty:
@@ -339,12 +333,13 @@ class parpool(object):
def __call__(self, n, fun=None, args=None, kwargs=None, handle=None):
""" Add new iteration, using optional manually defined handle."""
if self.is_alive and not self.E.is_set():
n = dumps(n, recurse=True)
if not fun is None:
if fun is not None:
self.fun = fun
if not args is None:
if args is not None:
self.args = args
if not kwargs is None:
if kwargs is not None:
self.kwargs = kwargs
while self.Qi.full():
self._getfromq()
@@ -355,13 +350,13 @@ class parpool(object):
self.Qi.put((handle, n, self.fun, self.args, self.kwargs))
self._qbar_update()
return handle
elif not handle in self:
elif handle not in self:
self.handles.append(handle)
self.Qi.put((handle, n, self.fun, self.args, self.kwargs))
self._qbar_update()
def _qbar_update(self):
if not self.qbar is None:
if self.qbar is not None:
try:
self.qbar.n = self.Qi.qsize()
except:
@@ -373,9 +368,9 @@ class parpool(object):
def __getitem__(self, handle):
""" Request result and delete its record. Wait if result not yet available. """
if not handle in self:
if handle not in self:
raise ValueError('No handle: {}'.format(handle))
while not handle in self.res:
while handle not in self.res:
self._getfromq()
self.handles.remove(handle)
return self.res.pop(handle)
@@ -402,20 +397,34 @@ class parpool(object):
def close(self):
if self.is_alive:
self.is_alive = False
self.E.set()
self.P.close()
while self.A.value:
self._empty_queue(self.Qi)
self._empty_queue(self.Qo)
self._empty_queue(self.Qi)
self._empty_queue(self.Qo)
self.P.join()
self._close_queue(self.Qi)
self._close_queue(self.Qo)
self.P.close()
self.P.join()
self.is_alive = False
self.res = {}
self.handle = 0
self.handles = []
@staticmethod
def _empty_queue(Q):
if not Q._closed:
while not Q.empty():
try:
Q.get(True, 0.02)
except multiprocessing.queues.Empty:
pass
@staticmethod
def _close_queue(Q):
if not Q._closed:
while Q.full():
while not Q.empty():
try:
Q.get(True, 0.02)
except multiprocessing.queues.Empty:
@@ -425,15 +434,22 @@ class parpool(object):
class _worker(object):
""" Manages executing the target function which will be executed in different processes. """
def __init__(self, Qi, Qo, E, terminator, debug=False, cachesize=48):
def __init__(self, Qi, Qo, A, E, terminator, cachesize=48):
self.cache = []
self.Qi = Qi
self.Qo = Qo
self.A = A
self.E = E
self.terminator = dumps(terminator, recurse=True)
self.debug = debug
self.cachesize = cachesize
# print(self.terminator)
def add_to_q(self, value):
while not self.E.is_set():
try:
self.Qo.put(value, timeout=0.1)
break
except multiprocessing.queues.Full:
continue
def __call__(self):
while not self.E.is_set():
@@ -443,17 +459,17 @@ class parpool(object):
fun = self.get_from_cache(*Fun)
args = self.get_from_cache(*Args)
kwargs = self.get_from_cache(*Kwargs)
self.Qo.put((None, i, dumps(fun(dill.loads(n), *args, **kwargs), recurse=True)))
self.add_to_q((False, i, dumps(fun(dill.loads(n), *args, **kwargs), recurse=True)))
except multiprocessing.queues.Empty:
continue
except:
if self.debug:
self.Qo.put((True, i, dumps(format_exc(), recurse=True)))
else:
self.Qo.put((False, i, (n, Fun, Args, Kwargs)))
self.add_to_q((True, i, (n, Fun[1], Args[1], Kwargs[1], dumps(format_exc(), recurse=True))))
self.E.set()
terminator = dill.loads(self.terminator)
if not terminator is None:
if terminator is not None:
terminator()
with self.A.get_lock():
self.A.value -= 1
def get_from_cache(self, h, ser):
if len(self.cache):
@@ -466,8 +482,9 @@ class parpool(object):
self.cache.pop(0)
return obj
def pmap(fun, iterable=None, args=None, kwargs=None, length=None, desc=None, bar=True, qbar=False, terminator=None,
rP=1, nP=None, serial=4, debug=False):
rP=1, nP=None, serial=4):
""" map a function fun to each iteration in iterable
best use: iterable is a generator and length is given to this function
@@ -483,7 +500,6 @@ def pmap(fun, iterable=None, args=None, kwargs=None, length=None, desc=None, bar
rP: ratio workers to cpu cores, default: 1
nP: number of workers, default, None, overrides rP if not None
serial: switch to serial if number of tasks less than serial, default: 4
debug: if an error occurs in an iteration, return the erorr instead of retrying in the main process
"""
args = args or ()
kwargs = kwargs or {}
@@ -496,7 +512,7 @@ def pmap(fun, iterable=None, args=None, kwargs=None, length=None, desc=None, bar
else: # parallel case
with tqdmm(total=0, desc='Task buffer', disable=not qbar, leave=False) as qbar,\
tqdm(total=length, desc=desc, disable=not bar) as bar:
with parpool(fun, args, kwargs, rP, nP, bar, qbar, terminator, debug) as p:
with parpool(fun, args, kwargs, rP, nP, bar, qbar, terminator) as p:
length = 0
for i, j in enumerate(iterable): # add work to the queue
p[i] = j

2
setup.py
View File

@@ -5,7 +5,7 @@ with open("README.md", "r") as fh:
setuptools.setup(
name="parfor",
version="2021.3.1",
version="2021.3.2",
author="Wim Pomp",
author_email="wimpomp@gmail.com",
description="A package to mimic the use of parfor as done in Matlab.",