python多進程
阿新 • • 發佈:2017-07-01
python 多進程
第一種開啟進程方式
#!/usr/bin/python # -*- coding:utf-8 -*- from multiprocessing import Process import time, random, os # print(os.cpu_count()) # # # # 定義一個任務 # def piao(name): # print(‘%s is piaoing‘ % name) # time.sleep(3) # cpu阻塞,切換到主進程 # print(‘%s is piao end‘ % name) # # # if __name__ == ‘__main__‘: # # target指定執行目標,args指定位置參數,指定為元組,kwargs指定字典 # p1 = Process(target=piao, args=(‘lh‘,),name=‘<p1>‘) # 產生對象 # # 創建子進程,賦值主進程地址空間,開啟一個子進程,創建進程需要時間, # # 發送系統調用,只是一個系統調用,指揮操作系統啟動子進 # # 程,主進程並不等待子進程 # p1.start() # 開啟子進程 # # time.sleep(1) # # print(‘主進程‘) # # 誰先執行完誰先打印
第二種,自定義進程類
class Piao(Process): def __init__(self, name): super().__init__() # 重用父類方法, self.name = name def run(self): # 方法名必須為run print(‘%s is piaoing...‘ % self.name) time.sleep(3) print(‘%s is piao end‘ % self.name) if __name__ == ‘__main__‘: p1 = Piao(‘lh‘) p1.start() # 相當於p1.run() print(‘主進程‘)
鎖
#!/usr/bin/python # -*- coding:utf-8 -*- # import threading, time # # v = 10 # # lock = threading.Lock() #只能有一個使用鎖 # lock = threading.RLock() # 遞歸鎖 # # # def task(arg): # time.sleep(2) # lock.accquire() # 申請使用鎖,其他線程等待 # global v # v -= 1 # print(v) # lock.release() # 交還釋放 # for i in range(10): # t = threading.Thread(target=task, args=(i,)) # t.start() # 多個人同時使用鎖,一批批操作 # import threading, time # # v = 10 # # lock = threading.BoundedSemaphore(3) #同時三個使用該鎖 # # lock = threading.RLock() # 遞歸鎖 # # # def task(arg): # # lock.acquire() # 申請使用鎖,其他線程等待 # time.sleep(1) # global v # v -= 1 # print(v) # lock.release() # 交還釋放 # # for i in range(10): # t = threading.Thread(target=task, args=(i,)) # t.start() # 時間鎖.解脫鎖的限制 # import threading, time # # v = 10 # # lock = threading.Event() # 同時三個使用該鎖 # # # # lock = threading.RLock() # 遞歸鎖 # # # def task(arg): # time.sleep(1) # lock.wait() # 鎖住多有線程 # print(arg) # # # for i in range(10): # t = threading.Thread(target=task, args=(i,)) # t.start() # # while True: # value = input(‘>>>‘) # if value == ‘1‘: # lock.set() # lock.clear() #想怎麽鎖就怎麽鎖 import threading, time v = 10 lock = threading.Condition() # 同時三個使用該鎖 # lock = threading.RLock() # 遞歸鎖 def task(arg): time.sleep(1) lock.acquire() lock.wait()# 鎖住多有線程 print(arg) lock.release() for i in range(10): t = threading.Thread(target=task, args=(i,)) t.start() while True: value = input(‘>>>‘) lock.acquire() lock.notify(int(value)) lock.release()
進程對象的方法和屬性
from multiprocessing import Process import time, random # def piao(name): # print(‘%s is piaoing‘ % name) # time.sleep(random.randint(1, 3)) # print(‘%s is piao end‘ % name) # # # if __name__ == ‘__main__‘: # p1 = Process(target=piao, args=(‘egon‘,)) # p2 = Process(target=piao, args=(‘lh‘,)) # p3 = Process(target=piao, args=(‘apla‘,)) # p4 = Process(target=piao, args=(‘tom‘,)) # # # 開啟順序不一定,誰先執行完誰打印 # p1.start() # 不是阻塞操作,在發系統調用 # p2.start() # 不是阻塞操作,在發系統調用 # p3.start() # 不是阻塞操作,在發系統調用 # p4.start() # 不是阻塞操作,在發系統調用 # # # p1.join() # 主進程等待p1執行完畢,hold # # p1.join() # 主進程等待 # # p2.join() # # p3.join() # # p4.join() # p_l = [p1, p2, p3, p4] # for p in p_l: # p.start() # # for p in p_l: # p.join() # print(‘主進程‘) # 每次都是主進程先打印,原因是cpu性能低 # 守護進程 def piao(name): print(‘%s is piaoing‘ % name) time.sleep(random.randint(1, 3)) print(‘%s is piao end‘ % name) if __name__ == ‘__main__‘: p1 = Process(target=piao, args=(‘egon‘,)) p1.daemon = True # 主進程運行完成後子進程執行完也會被回收 p1.start() print(p1.pid) print(p1.name) print(p1.is_alive()) # True p1.terminate() # 把p1幹掉,僵屍進程 time.sleep(0.5) print(p1.is_alive()) # False 不能立即幹掉進程 print(‘主進程‘)
進程同步之模擬搶票
from multiprocessing import Process, Lock import json, time, random def work(dbfile, name, lock): # lock.acquire() # 加鎖,誰先拿到,其他進程無法使用,加鎖是並發,join是排隊 with lock: # 上下文管理 with open(dbfile, encoding=‘utf-8‘) as f: dic = json.loads(f.read()) if dic[‘count‘] > 0: dic[‘count‘] -= 1 time.sleep(random.randint(1, 3)) # 模擬網絡延遲 with open(dbfile, ‘w‘, encoding=‘utf-8‘) as f: f.write(json.dumps(dic)) print(‘%s搶票成功!!!‘ % name) else: print(‘%s搶票失敗!!!‘ % name) # lock.release() # 鎖要釋放,不然其他的進程無法使用 if __name__ == ‘__main__‘: lock = Lock() p_l = [] for i in range(100): p = Process(target=work, args=(‘a.txt‘, ‘用戶%s‘ % i, lock)) p_l.append(p) p.start() for p in p_l: p.join() print(‘主進程‘)
生產者消費者模型
from multiprocessing import Process, JoinableQueue import random, time def consumer(q, name): while True: # time.sleep(random.randint(1, 3)) res = q.get() # 一直在取狀態 q.task_done() # 執行完成 # if res is None: # break print(‘\033[41m消費者%s拿到%s\033[0m‘ % (name, res)) def producer(seq, q, name): for item in seq: # time.sleep(random.randint(1, 3)) q.put(item) print(‘\033[42m生產者%s拿到%s\033[0m‘ % (name, item)) # q.put(None) q.join() print(‘**************>>‘) # 本行執行說明生產者執行完成,消費者把所有任務執行 if __name__ == ‘__main__‘: q = JoinableQueue() c = Process(target=consumer, args=(q, ‘lh‘)) c.daemon=True #設置守護進程,朱金城結束,c就結束 c.start() seq = [‘包子%s‘ % i for i in range(10)] p = Process(target=producer, args=(seq, q, ‘廚師1‘)) p.start() # 生產者進程 p.join() # 主進程等待p結束,p等待c把數據取完,c一旦取完數據,p.join就不在阻塞,進而追進程結束 # ,主進程結束會回收守護進程c,而且此時c也沒有存在的必要只要join生產者就行,生產者在等待消費者取走 # c.join() print(‘主進程‘) # [i for i in range(10)] 列表生成式 # [i for i in range(10) if i > 5] 列表生成式
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python多進程