Re: Multithread heap assertion failure

From:
 Zhiguo <ZhiguoYoung@gmail.com>
Newsgroups:
microsoft.public.vc.mfc
Date:
Thu, 09 Aug 2007 07:23:16 -0700
Message-ID:
<1186669396.115690.80500@g12g2000prg.googlegroups.com>
On Aug 9, 10:07 pm, "Scott McPhillips [MVP]" <org-dot-mvps-at-
scottmcp> wrote:

Zhiguo wrote:

HI, all of you,

I have created a Win32 console project with MFC support(shared dll) to
test my multithread programming.
When run, a "Debug assertion failure" occures at the following
expression:
_ASSERTE(_CrtIsValidHeapPointer(pUserData));

I cannot figure out why the exception occurs. Can you shed some light
on me?

Any help appreciated. Thansk in advance.

^_^

The only source file is as follows:

//--------------------------------------------------
#include <afx.h>
#include <afxmt.h>
#include <afxwin.h>
#include <windows.h>

#include <iostream>
using namespace std;

class CTestThread: public CWinThread{
public:
   CTestThread(){}
   virtual ~CTestThread(){}

   int Run(){
           cout << "run..." << endl;
           return 1;
   }

   BOOL InitInstance(){
           cout << "init..." << endl;
           return TRUE;
   }

   int ExitInstance(){
           cout << "exit inst..." << endl;
           return 0;
   }
};

int main(){
   int nWorkerNum = 2;
   CTestThread * m_pThread = new CTestThread[nWorkerNum];
   HANDLE * m_pThreadHandle = new HANDLE[nWorkerNum];
   for(int i = 0; i < nWorkerNum; i ++){
           m_pThread[i].CreateThread();
           m_pThreadHandle[i] = m_pThread[i].m_hThread;
   }
   WaitForMultipleObjects(nWorkerNum, m_pThreadHandle, TRUE, INFINITE);
   cout << "Press any key to conitnue..." << endl;
   char c; cin >> c;
}
//--------------------------------------------------


When you exit from the thread CWinThread normally does

  delete this;

If the thread runs and exits very quickly this makes your
m_pThread[i].m_hThread use an invalid pointer.

You can avoid this problem like this:

m_pThread[i].CreateThread(CREATE_SUSPENDED);
m_pThread[i].m_bAutoDelete = FALSE;
m_pThreadHandle[i] = m_pThread[i].m_hThread;
m_pThread[i].ResumeThread();

With this change you also should delete m_pThread[i] after
WaitForMultipleObjects returns.

--
Scott McPhillips [MVP VC++]


It works. Thank you very much!

^_^

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