Python Lock互斥锁详解 - 多线程同步与数据安全

# 线程同步Lock相关语法示例
import threading

# 创建锁
lock = threading.Lock()

# 方式1: acquire/release
lock.acquire()      # 获取锁（阻塞）
lock.acquire(timeout=5)  # 带超时的获取
try:
    # 临界区代码
    pass
finally:
    lock.release()  # 释放锁

# 方式2: with语句（推荐）
with lock:
    # 临界区代码
    pass

# Lock方法
lock.acquire(blocking=True, timeout=-1)  # 获取锁
lock.release()       # 释放锁
lock.locked()        # 检查是否被锁定

# 基本用法示例
import threading

# 共享资源
counter = 0
lock = threading.Lock()

def increment():
    """线程安全的计数器递增"""
    global counter
    for _ in range(100000):
        with lock:  # 使用with语句自动管理锁
            counter += 1

# 创建多个线程
threads = []
for i in range(5):
    t = threading.Thread(target=increment)
    threads.append(t)
    t.start()

# 等待所有线程完成
for t in threads:
    t.join()

print(f"最终计数: {counter}")  # 应该是 500000

# 详细代码示例：银行账户线程安全操作
import threading
import time
import random

class BankAccount:
    """线程安全的银行账户"""
    def __init__(self, balance=0):
        self.balance = balance
        self.lock = threading.Lock()
    
    def deposit(self, amount):
        """存款"""
        with self.lock:
            old_balance = self.balance
            time.sleep(0.001)  # 模拟操作延迟
            self.balance = old_balance + amount
            print(f"存入 {amount}，余额: {self.balance}")
    
    def withdraw(self, amount):
        """取款"""
        with self.lock:
            if self.balance >= amount:
                old_balance = self.balance
                time.sleep(0.001)
                self.balance = old_balance - amount
                print(f"取出 {amount}，余额: {self.balance}")
            else:
                print(f"余额不足，当前余额: {self.balance}")

# 创建账户
account = BankAccount(1000)

def deposit_worker(account, times):
    for _ in range(times):
        amount = random.randint(10, 100)
        account.deposit(amount)

def withdraw_worker(account, times):
    for _ in range(times):
        amount = random.randint(10, 50)
        account.withdraw(amount)

# 创建线程
threads = []
for i in range(3):
    t1 = threading.Thread(target=deposit_worker, args=(account, 5))
    t2 = threading.Thread(target=withdraw_worker, args=(account, 5))
    threads.extend([t1, t2])
    t1.start()
    t2.start()

for t in threads:
    t.join()

print(f"最终余额: {account.balance}")