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CString memory leak in cwinthread

When running my code I get this:

Detected memory leaks!
Dumping objects ->
strcore.cpp(118) : {86} normal block at 0x00302DF0, 31 bytes long.
 Data: <            Dude> 01 00 00 00 12 00 00 00 12 00 00 00 44 75 64 65
Object dump complete.

This is the code:
CString sD;
sD = "Dude this is weird";

If I comment out the second line only, the memory leak goes away.

This code is within a CWinThread object that is called from the main window and exits with a call to AfxEndThread(0); after sending a message back to the parent.  I can put this code in the parent window and it's fine.

There's another instance within the CWinThread object prior to these lines where this code is run:

CFtpConnection* pCon = NULL;
                     
try
      {
           pCon = parent->m_sSession->GetFtpConnection(FTP_SERVER, FTP_USER, FTP_PW, 21, TRUE);
      }
      catch (CInternetException* pEx)
      {
            CString sConnectionErrorMsg;
            TCHAR sz[1024];
            pEx->GetErrorMessage(sz, 1024);
            sConnectionErrorMsg.Format("Return error message: %s", sz);
            returnCode = UPDATE_CONNECTION_ERROR;
            m_sLog += "\r\nFTP connection failed\r\n" + sConnectionErrorMsg;
            pEx->Delete();
            delete pCon;
            pCon = NULL;
      }

Notice the use of CString object sConnectionErrorMsg here.  This does NOT create a memory leak.

Any ideas?
0
theclay
Asked:
theclay
2 Solutions
 
parnassoCommented:
My guess is that in the first case, when you end the thread with AfxEndThread(0), no destructor of the CString is called.

On the other hand, the code you written of the thread that uses the CString object sConnectionErrorMsg, DOES call the CString destructor and therefore, there is no memory leaks.

To solve your problem, wrap the first thread code in a function, and outside of that function called AfxEndThread so that every destructor get called because the objects get out of the scope.

Something like this.

functionDosomething()
{
  CString sD;
  sD = "Dude this is weird";
} // The object sD get out of scope so it will be released

functionThread()
{
   // do something
  functionDosomething();
  AfxEndThread(0);
}

Hope this helps
0
 
ZoppoCommented:
Hi,

I agree with parnasso - just as additional info: 'AfxEndThread' internally uses '_endthreadex'. http://msdn.microsoft.com/en-us/library/hw264s73%28v=VS.100%29.aspx says: '_endthread and _endthreadex cause C++ destructors pending in the thread not to be called'

ZOPPO
0
 
sarabandeCommented:
you should omit the AfxEndThread. simply return from thread function.

Sara
0
 
theclayAuthor Commented:
That took care of it - thanks.
0

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