boost::mutex error

Hi,
I'm learning boost::thread from a tutorial. This is the code from that tutorial:

Code:

---

#include <boost/thread.hpp>
#include <boost/date_time.hpp>
#include <iostream>

boost::mutex mutex;

void wait(int seconds)
{
    boost::this_thread::sleep(boost::posix_time::seconds(seconds));
}

void thread()
{
    try
    {
        for( int i = 0; i < 5; i++)
        {
            wait(1);
            boost::lock_guard<boost::mutex> lock(mutex);
            std::cout<<"Thread "
                << boost::this_thread::get_id()
                << ": " << i <<std::endl;
            mutex.unlock();

        }
    }
    catch(boost::thread_interrupted&)
    {
        std::cout<<"Thread Interrupted" << std::endl;
    }
}

int main()
{
    boost::thread t1(thread);
    boost::thread t2(thread);

    t1.join();
    t2.join();

    return 0;
}

---

This code ran then crashed at the end:

Quote:

---

Thread 0x12c22a0: 0
Thread 0x12c2010: 0
Thread 0x12c22a0: 1
Thread 0x12c2010: 1
Thread 0x12c22a0: 2
Thread 0x12c2010: 2
Thread 0x12c22a0: 3
Thread 0x12c2010: 3
Thread 0x12c22a0: 4
Thread 0x12c2010: 4
/usr/include/boost/thread/pthread/mutex.hpp:45: boost::mutex::~mutex(): Assertion `!pthread_mutex_destroy(&m)' failed.

---

why comes this crash the program? If i use boost::mutex::lock() and unlock() wouldn't crash the program, it won't crash.

The lock_guard object will call lock in its constructor, and unlock in its destructor. You don't need the mutex.unlock call.

Synchronization - Boost 1.46.1

gg

I didn't call mutex.lock() and unlocked() with lock_guard(). I get the error when I use lock_guard() by itself.

In the code in post #1, you need to remove the "mutex.unlock()" call to make the code correct.

gg

Aite. I swear that I took unlocked() out, scanned it so many time and didn't see it at all. Thanks for your help.