Unhandled exception in .exe 0xC0000005 access violation

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Hi,all:

When I was trying to design a thread pool, after thread job done, I need to notify the pool to do some work,like moving this thread from busy list to idle list,I designed 3 classes in 3 .h files:
1. CThreadPoolBase,an interface for an ending thread to notify the concrete thread pool to do some work:

/*CThreadPoolBase.h*/
clase CThreadPoolBase
{
public:
    virtual ~CThreadPoolBase()=0{}
    virtual void OnThreadFinished(LPVOID thr)=0; //para thr was used to pass a Thread*
}

2. CThreadPool: the concrete thread pool that fix the job:

/*CThreadPool.h  */
#include  "CThreadPoolBase.h"
class CThreadPool:public CThreadPoolBase
{
public:
    ...
    void   OnThreadFinished(LPVOID thr)
    {
      <pre lang="cs">CThread *pthr = static_cast<CThread*>(thr);
    if( pthr != NULL )
        MoveToIdleList(pthr); //move itself to idle list
    else
    {
        cout<<"\t***[ERR_OnThreadFinished], Received error thread notify."<<endl;
        return;
    }
    int noff = GetIdleNum()-GetInitNum();
    if (noff>0) //if too many idle threads, kill some
    {
        DeleteIdleThread(noff);
    }

}

}

3. Thread: class of thread handling:

#include  "CThreadPoolBase.h
class Thread:
{
public:
    Thread(CThreadPoolBase *pool=NULL):m_pool(pool){}
    ~Thread(){}
    ... 

BOOL Thread::OnTask()     
{
    ...// do some work here
    
    //notify the pool that 'this' thread has finished its work
    m_pool->OnThreadFinished(this);	//Exception caught <big>sometimes</big>
    return TRUE;
}
private:
    CThreadPoolBase *m_pool;
}

I got this exception:
Unhandled exception in .exe 0xC0000005 access violation

25: m_pool->OnThreadFinished(this);
0040205C mov esi,esp
0040205E mov ecx,dword ptr [ebp-4]
00402061 push ecx
00402062 mov edx,dword ptr [ebp-4]
00402065 mov ecx,dword ptr [edx+50h]
00402068 mov eax,dword ptr [ebp-4]
0040206B mov edx,dword ptr [eax+50h]
0040206E mov eax,dword ptr [edx] //it stopped here
00402070 call dword ptr [eax+4]
00402073 cmp esi,esp
00402075 call __chkesp (0040ed50)

Anybody would kindly tell me, what's the problem, and how did it happen?
Thank you !

Posted 9-Mar-11 16:49pm

scu_sundy

Updated 14-Mar-11 18:30pm

v6

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Comments

Stephen Hewitt 10-Mar-11 0:39am

The first thing to do is attempt to reproduce the problem in a debug build. Actually, this looks like a debug build looking at the machine code. Why isn't there any source?

LaxmikantYadav 10-Mar-11 2:07am

Error 0xC0000005 means the program has attempted to access memory that it shouldn't. You need to read the error log, or post it here.

mbue 10-Mar-11 6:05am

It seems your class is destroyed while the thread is running. If you're using COM, you should AddRef on the beginning of your thread and Release at the end. Otherwise you should enshure your class cannot been deleted while thread is running. You can do that in your destructor you mut wait until the thread execution is finished by WaitForSingleObject(hYourThread,INFINITE).
Regards.

Rajesh Katalkar 15-Mar-11 1:20am

where are you allocating memory for m_pool member in your cthread class.

scu_sundy 15-Mar-11 1:30am

I dont need allocate memory in class 'Thread',m_pool was passed and set to "CThreadPool*" after Thread object was created in CThreadPool::CThreadPool().

4 solutions

Solution 1

This problem have to resolved by some changes in settings as given below
project properties --> general --> Project Defaults-->Use of MFC
To set the properties "Use MFC In A Shared DLL".

This will solve your problem.

Posted 9-Mar-11 17:21pm

Ramalinga Koushik

Comments

scu_sundy 9-Mar-11 23:34pm

thank you!
Problem still found after this setting.

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Hans Dietrich · Accepted Answer · 2011-03-09T18:27:00

Solution 2

What do you see when you step through your code in the debugger?

Posted 9-Mar-11 18:27pm

Hans Dietrich

Comments

scu_sundy 10-Mar-11 0:40am

stop here:
25: m_pool->OnThreadFinished(this);
and got this:
Unhandled exception in .exe 0xC0000005 access violation

Niklas L 10-Mar-11 7:32am

Inspect your variables. It's either m_pool, this or *this that contains improper values. Verify that their respective members are looking ok. When you know this, you have better chances of finding the offending code.

scu_sundy 15-Mar-11 1:59am

I've found that it was the m_pool got a 'NULL' value caused the problem, but why ? I passed and set m_pool when Thread was created. And problems wont happen at first,which is meaned that some of 'Thread::m_pool != NULL', how did it happend?

Niklas L 15-Mar-11 5:17am

In your Thread class, make some pre- and post-condition checks in your functions. E.g add ASSERT(m_pool != NULL); first and last in every function. If someone is setting m_pool to NULL somewhere, you will catch him quickly.

Albert Holguin · Accepted Answer · 2011-03-14T16:50:00

Solution 3

This call is a direct call to the thread manager (non-thread safe!):

m_pool->OnThreadFinished(this);

Its bound to cause problems because you actually DeleteIdleThread() within it (you try to delete the thread that called the method). The proper way of doing this within MFC would be to PostMessage() when you're done and wait for a synchronization signal. If you're not using MFC, just look up non-blocking thread calls and/or synchronization methods for whatever your framework happens to be.

Posted 14-Mar-11 16:50pm

Albert Holguin

Updated 14-Mar-11 16:52pm

v2

Comments

scu_sundy 15-Mar-11 0:00am

Thank you Albert.
Fisrt of all, I ditn't use MFC;
second,I had tryed to debug and find the problem by change the Interface funtion OnThreadFinished()like this:
/*CThreadPoolBase.h*/clase CThreadPoolBase{public: virtual ~CThreadPoolBase()=0{} virtual void OnThreadFinished(/*LPVOID thr*/)=0; //NO Para passed }

And in CThreadPool::OnThreadFinished((/*LPVOID thr*/)
{/*it doing nothing*/}

In Thread::Ontask()
{
m_pool->OnThreadFinished(/*this*/);
}

After change, Problems still found!

Albert Holguin 15-Mar-11 0:11am

did you make sure that m_pool was what you expect it to be?

scu_sundy 15-Mar-11 0:42am

Yes,I'm sure that in the pool when thread was created, the CThreadPool* was passed to Thread::Thread(CThreadPoolBase* pool),code like below:

CThreadPool::CThreadPool(const int initnum)
{ for (int i=0;i

Albert Holguin 15-Mar-11 0:46am

Where's the section of code where you generate the CThread (or Thread) object?

scu_sundy 15-Mar-11 1:15am

In class CThreadPool's constructor, I create an initial list of thread,I passed this(that is CThreadPool*) to each thread:

Thread* thr = new Thread(this);AppendToIdleList(thr);

so that Thread::m_pool was pointed to the right concrete POOL.

Albert Holguin 15-Mar-11 1:33am

that seems fine, make sure that the value in "this" matches the pointer m_pool right when you make that call to OnThreadFinished(), hopefully you have a debugger that'll allow you to break and see the values.

scu_sundy 15-Mar-11 1:48am

My god,I debuged the program,when exception was caught and debug stopped,m_pool = 0x00000000.How could it be ? I've already passed the right CThreadPool* to class 'Thread''s constructor, I'm absolutely confused:

try
{
m_pool->OnThreadFinished();

}
catch (...)
{
std::cout<<"\t*** [ERR] *** :: Error happened CWorkThread::OnTask(LPVOID lpvData)"<<std::endl;
}

Espen Harlinn 17-Mar-11 10:52am

Good effort - a 5 :)

scu_sundy · Accepted Answer · 2011-03-14T20:53:00

I have found the problem,It's my fault,error was found in function CreateIdleThreadused to create idle threads dynamicly when necessary:

void CThreadPool::CreateIdleThread(const int num)
{

C#

for (int i=0;i<num;i++)
    {
        Thread *thr = new Thread(/*here I forgot to pass pointer this */);       

        AppendToIdleList(thr);
        m_VarMutex.Lock();
        m_nAvailNum++;
        m_VarMutex.Unlock();
        printf("\t\tCreate %d Idle thread . All=%d, busy=%d,Idle=%d\n",num,m_ThreadList.size(),m_BusyList.size(),m_IdleList.size());

        printf("*** Thanks a lot and best regards to all of you !! ^|^ ***\n");
   }

}

Unhandled exception in .exe 0xC0000005 access violation

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Solution 2

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Solution 1

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