Python開發之多個定時任務在單執行緒下執行的實例分析
- 黄舟原創
- 2017-07-27 16:03:231848瀏覽
單一執行緒多定時任務
1、初始版本：
#想法：計時器，說白了就是延時執行指定的程序，目前自己重構python裡面的定時器不太現實，能力達不到，所以延時操作時還得用到系統定時器，不過我們可以改一下規則；把所有要進行定時操作的程序添加到特定列表中，把列表中定時時間最短程序拿出來，進行threading.Timer（time，callback）綁定，等時間超時觸發自定義的callback，執行剛剛列表取出的程序；然後把時間更新，再次把列表中時間最短的程式拿出了，繼續threading.Timer綁定，不斷的迭代循環；當有新的定時任務加入到列表時，把當前的threading.Timer綁定取消，更新清單中的時間，再次取出最短時間，進行threading.Timer綁定......
#程式碼：
import threading
import time
class Timer():
'''单线程下的定时器'''
def __init__(self):
self.queues = []
self.timer = None
self.last_time = time.time()
def start(self):
item = self.get()
if item:
self.timer = threading.Timer(item[0],self.execute)
self.timer.start()
def add(self,item):
print('add',item)
self.flush_time()
self.queues.append(item)
self.queues.sort(key=lambda x:x[0])
if self.timer:
self.timer.cancel()
self.timer = None
self.start()
def get(self):
item = None
if len(self.queues) > 0:
item = self.queues[0]
return item
def pop(self):
item = None
if len(self.queues) > 0:
item = self.queues.pop(0)
return item
def flush_time(self):
curr_time = time.time()
for i in self.queues:
i[0] = i[0] - (curr_time - self.last_time)
self.last_time = curr_time
def execute(self):
# if self.timer:
# self.timer.cancel()
# self.timer = None
item = self.pop()
self.flush_time()
if item:
callback = item[1]
args = item[0]
callback(args)
self.start()執行與輸出：
if __name__ == '__main__': # 检测线程数
def func(): while True: print(threading.active_count())
time.sleep(1)
f1 = threading.Thread(target=func)
f1.start()
import logging
logging.basicConfig(level=logging.INFO,format="%(asctime)s %(message)s", datefmt="%m/%d/%Y %H:%M:%S [%A]") def func1(*args):
logging.info('func1 %s'%args) # time.sleep(5)
def func2(*args):
logging.info('func2 %s' % args) # time.sleep(5)
def func3(*args):
logging.info('func3 %s' % args) # time.sleep(5)
def func4(*args):
logging.info('func4 %s' % args) # time.sleep(5)
def func5(*args):
logging.info('func5 %s' % args) # time.sleep(5)
# 测试
t1 = Timer()
logging.info('start')
t1.add([5,func1])
time.sleep(0.5)
t1.add([4,func2])
time.sleep(0.5)
t1.add([3,func3])
time.sleep(0.5)
t1.add([2,func4])
time.sleep(0.5)
t1.add([1,func5])
time.sleep(5)
t1.add([1,func1])
t1.add([2,func2])
t1.add([3,func3])
t1.add([4,func4])
t1.add([5,func5])
# 输出
# 2
# 07/27/2017 10:36:47 [Thursday] start
# add [5, <function func1 at 0x000000D79FC77E18>]
# add [4, <function func2 at 0x000000D79FCA8488>]
# 3
# add [3, <function func3 at 0x000000D79FCA8510>]
# add [2, <function func4 at 0x000000D79FCA8598>]
# 3
# add [1, <function func5 at 0x000000D79FCA8620>]
# 3
# 07/27/2017 10:36:50 [Thursday] func5 1
# 07/27/2017 10:36:51 [Thursday] func4 0.498349666595459
# 3
# 07/27/2017 10:36:51 [Thursday] func3 0.49782633781433105
# 07/27/2017 10:36:52 [Thursday] func2 0.49848270416259766
# 3
# 07/27/2017 10:36:52 [Thursday] func1 0.48449039459228516
# 2
# 2
# add [1, <function func1 at 0x000000D79FC77E18>]
# add [2, <function func2 at 0x000000D79FCA8488>]
# add [3, <function func3 at 0x000000D79FCA8510>]
# add [4, <function func4 at 0x000000D79FCA8598>]
# add [5, <function func5 at 0x000000D79FCA8620>]
# 3
# 07/27/2017 10:36:55 [Thursday] func1 0.9990766048431396
# 3
# 07/27/2017 10:36:56 [Thursday] func2 0.9988017082214355
# 3
# 07/27/2017 10:36:57 [Thursday] func3 0.99928879737854
# 07/27/2017 10:36:58 [Thursday] func4 0.9991350173950195
# 3
# 3
# 07/27/2017 10:36:59 [Thursday] func5 0.9988160133361816執行程式碼
註：查看程式碼輸出，所有的計時器都按照標定的時間依次執行，非常完美，一切看起來很美好，只是看起來，呵呵噠，當你把func裡面的time.sleep(5)啟用後，線程數蹭蹭的上來了;原因是上個定時器callback還是執行中，下個定時器已經啟動了，這時就又新增了一個線程，哎,失敗
2、修訂版本
想法：利用生成者消費者模型,用到threading.Condition條件變數；強制永遠啟用的是一個Timer!
程式碼：
##
import time
import threading
import logging
class NewTimer(threading.Thread):
'''单线程下的定时器'''
def __init__(self):
super().__init__()
self.queues = []
self.timer = None
self.cond = threading.Condition()
def run(self):
while True:
# print('NewTimer',self.queues)
self.cond.acquire()
item = self.get()
callback = None
if not item:
logging.info('NewTimer wait')
self.cond.wait()
elif item[0] <= time.time():
new_item = self.pop()
callback = new_item[1]
else:
logging.info('NewTimer start sys timer and wait')
self.timer = threading.Timer(item[0]-time.time(),self.execute)
self.timer.start()
self.cond.wait()
self.cond.release()
if callback:
callback(item[0])
def add(self, item):
# print('add', item)
self.cond.acquire()
item[0] = item[0] + time.time()
self.queues.append(item)
self.queues.sort(key=lambda x: x[0])
logging.info('NewTimer add notify')
if self.timer:
self.timer.cancel()
self.timer = None
self.cond.notify()
self.cond.release()
def pop(self):
item = None
if len(self.queues) > 0:
item = self.queues.pop(0)
return item
def get(self):
item = None
if len(self.queues) > 0:
item = self.queues[0]
return item
def execute(self):
logging.info('NewTimer execute notify')
self.cond.acquire()
self.cond.notify()
self.cond.release()
#執行與輸出：
if __name__ == '__main__': def func(): while True: print(threading.active_count())
time.sleep(1)
f1 = threading.Thread(target=func)
f1.start()
logging.basicConfig(level=logging.INFO,format="%(asctime)s %(message)s", datefmt="%m/%d/%Y %H:%M:%S [%A]")
newtimer = NewTimer()
newtimer.start() def func1(*args):
logging.info('func1 %s'%args)
time.sleep(5) def func2(*args):
logging.info('func2 %s' % args)
time.sleep(5) def func3(*args):
logging.info('func3 %s' % args)
time.sleep(5) def func4(*args):
logging.info('func4 %s' % args)
time.sleep(5) def func5(*args):
logging.info('func5 %s' % args)
time.sleep(5)
newtimer.add([5,func1])
newtimer.add([4,func2])
newtimer.add([3,func3])
newtimer.add([2,func4])
newtimer.add([1,func5])
time.sleep(1)
newtimer.add([1,func1])
newtimer.add([2,func2])
newtimer.add([3,func3])
newtimer.add([4,func4])
newtimer.add([5,func5])# 输出# 2# 07/27/2017 11:26:19 [Thursday] NewTimer wait# 07/27/2017 11:26:19 [Thursday] NewTimer add notify# 07/27/2017 11:26:19 [Thursday] NewTimer add notify# 07/27/2017 11:26:19 [Thursday] NewTimer add notify# 07/27/2017 11:26:19 [Thursday] NewTimer add notify# 07/27/2017 11:26:19 [Thursday] NewTimer add notify# 07/27/2017 11:26:19 [Thursday] NewTimer start sys timer and wait# 07/27/2017 11:26:20 [Thursday] NewTimer execute notify# 4# 07/27/2017 11:26:20 [Thursday] func5 1501125980.2175007# 07/27/2017 11:26:20 [Thursday] NewTimer add notify# 07/27/2017 11:26:20 [Thursday] NewTimer add notify# 07/27/2017 11:26:20 [Thursday] NewTimer add notify# 07/27/2017 11:26:20 [Thursday] NewTimer add notify# 07/27/2017 11:26:20 [Thursday] NewTimer add notify# 3# 3# 3# 3# 3# 07/27/2017 11:26:25 [Thursday] func4 1501125981.2175007# 3# 3# 3# 3# 07/27/2017 11:26:30 [Thursday] func1 1501125981.218279# 3# 3# 3# 3# 3# 3# 07/27/2017 11:26:35 [Thursday] func3 1501125982.2175007# 3# 3# 3# 3# 07/27/2017 11:26:40 [Thursday] func2 1501125982.218279# 3# 3# 3# 3# 3# 07/27/2017 11:26:45 [Thursday] func2 1501125983.2175007# 3# 3# 3# 3# 3# 07/27/2017 11:26:50 [Thursday] func3 1501125983.218279# 3# 3# 3# 3# 3# 07/27/2017 11:26:55 [Thursday] func1 1501125984.2175007# 3# 3# 3# 3# 3# 07/27/2017 11:27:00 [Thursday] func4 1501125984.218279# 3# 3# 3# 3# 3# 07/27/2017 11:27:05 [Thursday] func5 1501125985.218279# 3# 3# 3# 3# 3# 07/27/2017 11:27:10 [Thursday] NewTimer wait
輸出
###rrreee############### ###註：這次無論如何測試線程數也不會蹭蹭的上漲，同時可以實現多定時器任務要求；缺點：用到了兩線程，沒有用到單線程去實現，第二時間精準度問題，需要等待上個定時程式執行完畢，程式才能繼續執行#######
以上是Python開發之多個定時任務在單執行緒下執行的實例分析的詳細內容。更多資訊請關注PHP中文網其他相關文章！
陳述：
本文內容由網友自願投稿，版權歸原作者所有。本站不承擔相應的法律責任。如發現涉嫌抄襲或侵權的內容，請聯絡admin@php.cn