Python編程：threading多線程
進(jìn)程process：應(yīng)用程序以一個(gè)整體的形式暴露給操作系統(tǒng)管理，里邊包含對(duì)各種資源的調(diào)用，內(nèi)存的分配，對(duì)各種資源管理的集合
線程thread：操作系統(tǒng)最小的調(diào)度單位，是一串指令的集合
進(jìn)程 要操作cpu，必須先創(chuàng)建一個(gè)線程
進(jìn)程與線程區(qū)別：線程共享，進(jìn)程獨(dú)立
線程共享內(nèi)存空間，進(jìn)程內(nèi)存是獨(dú)立的
同一個(gè)進(jìn)程之間的線程可以直接通信，兩個(gè)進(jìn)程必須通過中間代理才能通信，創(chuàng)建新線程很簡單，創(chuàng)建新進(jìn)程需要對(duì)其父進(jìn)程進(jìn)行一次克隆
一個(gè)線程可以控制和操作統(tǒng)一進(jìn)程里的其他線程，進(jìn)程只能操作子進(jìn)程
GIL：Global Interpreter Lock
直接調(diào)用
import threading import time def run(n): print("task:", n) time.sleep(2) t1 = threading.Thread(target=run, args=("t1",)) t2 = threading.Thread(target=run, args=("t2",)) t3 = threading.Thread(target=run, args=("t3",)) t1.start() t2.start() t3.start() """ task: t1 task: t2 task: t3 """
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繼承式調(diào)用
import threading import time class MyThread(threading.Thread): def __init__(self, n, sleep_time): super(MyThread, self).__init__() self.n = n self.sleep_time = sleep_time def run(self): # 需要運(yùn)行的代碼 print("task:", self.n) time.sleep(self.sleep_time) print("task done", self.n, threading.current_thread(), threading.active_count()) t1 = MyThread("t1", 2) t2 = MyThread("t2", 3) t3 = MyThread("t3", 4) t1.start() t2.start() t3.start() # 等待線程執(zhí)行完畢繼續(xù)主線程，阻塞 t1.join() # wait() t2.join() t3.join() print("...main...", threading.current_thread(), threading.active_count()) # 主線程 """ task: t1 task: t2 task: t3 task done t1
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多線程調(diào)用
# 主線程與子線程是并行的 import threading import time def run(n): print("task:", n) time.sleep(2) print("task done", n) start_time = time.time() threads = [] # 保存線程列表 for i in range(5): t = threading.Thread(target=run, args=("t%s"%i,)) t.start() threads.append(t) # 將所有線程阻塞 for t in threads: t.join() end_time = time.time() print("time:", end_time - start_time) """ task: t0 task: t1 task: t2 task: t3 task: t4 task done t4 task done t2 task done t3 task done t1 task done t0 time: 2.0103650093078613 """
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守護(hù)線程
import threading import time def run(n): print("task:", n) time.sleep(2) print("task done", n) start_time = time.time() threads = [] # 保存線程列表 for i in range(5): t = threading.Thread(target=run, args=("t%s"%i,)) t.setDaemon(True) # 設(shè)置為守護(hù)線程，主線程停止隨之停止 t.start() threads.append(t) time.sleep(2) # 等待部分線程執(zhí)行完畢 end_time = time.time() print("time:", end_time - start_time) """ task: t0 task: t1 task: t2 task: t3 task: t4 task done t2 task done t4 task done t3 task done t1 task done t0 time: 2.0087130069732666 """
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互斥鎖
import threading import time num = 0 lock = threading.Lock() # 實(shí)例化互斥鎖 def run(n): global num lock.acquire() # 申請(qǐng)鎖 time.sleep(2) num += 1 lock.release() # 釋放鎖 print(num) start_time = time.time() threads = [] # 保存線程列表 for i in range(5): t = threading.Thread(target=run, args=("t%s"%i,)) t.start() threads.append(t) for thread in threads: thread.join() # 等待部分線程執(zhí)行完畢 end_time = time.time() print("time:", end_time - start_time) print("num:", num) """ 1 2 3 4 5 time: 10.027688980102539 num: 5 """
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遞歸鎖
import threading import time num = 0 lock = threading.RLock() # 實(shí)例化遞歸鎖,此處用普通互斥鎖會(huì)卡死 def run1(): print("run1_start") lock.acquire() # 第二級(jí)鎖 print("run1") lock.release() def run2(): lock.acquire() # 第二級(jí)鎖 print("run2") lock.release() def run(): lock.acquire() # 第一級(jí)鎖 print("run1_begin") run1() print("run2_begin") run2() print("run_end") lock.release() # 釋放鎖 start_time = time.time() t = threading.Thread(target=run) t.start() # t.join() # 等待全部線程執(zhí)行完畢 while threading.active_count() > 1: print(threading.current_thread()) end_time = time.time() print("time:", end_time - start_time) """ run1_begin <_MainThread(MainThread, started 22552)> <_MainThread(MainThread, started 22552)> <_MainThread(MainThread, started 22552)> run1_start <_MainThread(MainThread, started 22552)> run1 run2_begin run2 run_end time: 0.0 """
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信號(hào)鎖
import threading import time semaphore = threading.BoundedSemaphore(5) # 設(shè)置信號(hào)量，最多允許5個(gè)線程同時(shí)運(yùn)行 def run(n): semaphore.acquire() # 信號(hào)鎖 time.sleep(1) print("run", n) semaphore.release() start_time = time.time() for i in range(10): t = threading.Thread(target=run, args=(i,)) t.start() # 等待全部線程執(zhí)行完畢 while threading.active_count() != 1: pass end_time = time.time() print("time:", end_time - start_time) """ run 1 run 2 run 4 run 0 run 3 run 5 run 7 run 8 run 9 run 6 time: 2.061771869659424 """
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Python 任務(wù)調(diào)度 多線程
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