【发布时间】：2013-03-13 08:01:53
【问题描述】：
我在我的多线程代码中使用 scoped_lock 来独占访问代码的某些部分，但有时它会抛出异常访问冲突写入位置 ...。
boost::mutex mMutex;
boost::condition mInputQueueNotEmpty;
Job* MyThreadPool<Job, JobOutput>::GetNextJob()
{
boost::mutex::scoped_lock lock(mMutex);
while (mInputQueue.empty())
mInputQueueNotEmpty.wait(lock);
// Do something ...
}
我跟踪了代码，发现 basic_timed_mutex 类中有一个变量 active_count，并且每当发生运行时错误时，该变量都未初始化。 运行时错误发生在这里：
bool try_lock()
{
return !win32::interlocked_bit_test_and_set(&active_count,lock_flag_bit);
}
我不知道该怎么办！因为我无权访问这个变量，也不负责初始化它。
更新
我的函数类是这样的：
#pragma once
#include <vector.h>
#include <boost/thread.hpp>
#include "MyThread.h"
#include <queue>
#include <boost/thread/condition.hpp>
template <class Job, class JobOutput>
class MyThreadPool
{
public:
MyThreadPool(int processJobWhenArrived);
virtual ~MyThreadPool(void);
void Initialize(int ThreadsCount);
void AddJob(Job* job);
void StartProcess();
Job* GetNextJob();
virtual void FinishJob(Job* job, JobOutput* jobOutput);
void WaitUntilAllJobsProcessed();
public:
vector<MyThread<Job, JobOutput>*> mThreads;
queue<Job*> mInputQueue;
queue<pair<Job*,JobOutput*>> mOutputQueue;
boost::mutex mMutexAdd;
boost::mutex mMutex;
boost::condition mInputQueueNotEmpty;
boost::mutex mJobOutputMutex;
boost::mutex mJobsMutex;
boost::condition mProcessJobs;
bool mStartProcessJobs;
int mJobsInputCount;
int mJobsOutputCount;
int mPrevJobsOutputCount;
bool mProcessJobWhenArrived;
};
template <class Job, class JobOutput>
void MyThreadPool<Job, JobOutput>::Initialize(int threadsCount)
{
mStartProcessJobs = false;
for (int t = 0; t < threadsCount; t++)
mThreads.push_back(new MyThread<Job, JobOutput>(this));
}
template <class Job, class JobOutput>
void MyThreadPool<Job, JobOutput>::AddJob(Job* job)
{
boost::mutex::scoped_lock lock(mMutexAdd);
mInputQueue.push(job);
mJobsInputCount++;
if (mProcessJobWhenArrived)
mInputQueueNotEmpty.notify_all();
}
template <class Job, class JobOutput>
Job* MyThreadPool<Job, JobOutput>::GetNextJob()
{
boost::mutex::scoped_lock lock(mMutex);
if (mInputQueue.empty() && mStartProcessJobs && mJobsInputCount == mJobsOutputCount)
mProcessJobs.notify_one();
while (mInputQueue.empty())
mInputQueueNotEmpty.wait(lock);
Job* job = mInputQueue.front();
mInputQueue.pop();
return job;
}
这是我使用 GetNextJob 函数的代码：
#pragma once
#include <MyMemory.h>
#include <boost/thread.hpp>
template <class Job, class JobOutput>
class MyThreadPool;
template <class Job, class JobOutput>
class MyThread
{
public:
static void StaticRun(MyThread* p);
void Run();
public:
boost::thread mThread;
MyThreadPool<Job, JobOutput>* mThreadPool;
};
#include "MyThreadPool.h"
template <class Job, class JobOutput>
MyThread<Job, JobOutput>::MyThread(MyThreadPool<Job, JobOutput>* threadPool)
{
mThread = boost::thread(StaticRun, this);
mThreadPool = threadPool;
}
template <class Job, class JobOutput>
void MyThread<Job, JobOutput>::StaticRun(MyThread* p)
{
p->Run();
}
template <class Job, class JobOutput>
void MyThread<Job, JobOutput>::Run()
{
JobOutput *jobOutput;
while (true)
{
Job* job = mThreadPool->GetNextJob();
jobOutput = Process (job);
mThreadPool->FinishJob(job, jobOutput);
}
}
有一个类继承了 MyThreadPool
class SsThreadPool : public MyThreadPool<Job, JobOutput>
这就是使用线程池的地方：
class BPS
{
//...
SsThreadPool mJobsThreadPool;
//...
}
void BPS::Initialize()
{
mJobsThreadPool.Initialize(mConcurrentThreadsCount);
}
void BPS::f()
{
//...
for (int i = 0; i < jobsCount; i++)
{
//...
mJobsThreadPool.AddJob(job);
//...
}
mJobsThreadPool.StartProcess();
mJobsThreadPool.WaitUntilAllJobsProcessed();
//...
}
【问题讨论】：
-
这是您遇到访问冲突的实际代码吗？
-
mMutex是全局变量吗？您是否尝试从其他全局对象的构造函数中访问它？ -
是的，我在这一行遇到异常：
boost::mutex::scoped_lock lock(mMutex); -
@aleguna
mMutex不是全局变量，它是类的非静态成员，我只是从其类的函数中访问它。 -
然后发布真实代码。我 99.99% 确定问题出在其中，而不是在 boost 中。
标签： c++ boost locking mutex boost-thread