的boost :: scoped_lock的似乎不是鎖定性病::法院

Question

我使用升壓1.54.0和Visual Studio 2010的代碼：

#include <iostream> 
#include "boost/thread/thread.hpp" 
#include "boost/thread/mutex.hpp" 

boost::mutex mx1; 

void func1() 
{ 
    { 
     boost::mutex::scoped_lock(mx1); 
     std::cout << "Thread " << boost::this_thread::get_id() << " starting work." << std::endl; 
    } 
    int x = 0; 
    for (int i=0; i<100; i++) 
     x++; 
    { 
     boost::mutex::scoped_lock(mx1); 
     std::cout << "Thread " << boost::this_thread::get_id() << " finished." << std::endl; 
    } 
} 

int main(void) 
{ 
    boost::thread thread1(&func1); 
    boost::thread thread2(&func1); 
    thread1.join(); 
    thread2.join(); 
    return 0; 
} 

大約有一半的時間我得到以下（具有不同線程ID和執行順序，很明顯）：

Thread Thread 15b0 starting work. 
1a18 starting work. 
Thread 15b0 finished. 
Thread 1a18 finished. 

...而不是這個（這是我所期望的）：

Thread 15b0 starting work. 
Thread 1a18 starting work. 
Thread 15b0 finished. 
Thread 1a18 finished. 

但是，使用

mx1.lock(); 
std::cout << "Thread " << boost::this_thread::get_id() << " starting work." << std::endl; 
mx1.unlock(); 

...似乎沒有問題。

輸出總是似乎遵循相同的模式。我是否錯誤地使用了互斥鎖，或者它是否與std :: cout有關？

Answer 1

更換

boost::mutex::scoped_lock(mx1); 

與

boost::mutex::scoped_lock lock(mx1); 

你愛上了範圍的鎖最頻繁出現的錯字的受害者:-)