Re: Memory leak with CAsyncSocket::Create

"AliR \(VC++ MVP\)" <AliR@online.nospam>
Tue, 10 Jul 2007 09:45:46 -0500
I couldn't find a memory leak. What you are most likely seeing is windows
memory managment doing its work. The Create method is creating a socket
object, when when it's freed the memory is not given back to the system
right away.

(I used this method to detect a leak)

// Declare the variables needed
#ifdef _DEBUG
   CMemoryState oldMemState, newMemState, diffMemState;

   for (int i=0; i<10; ++i)
      CAsyncSocket *pAS = new CAsyncSocket;
      delete pAS;

#ifdef _DEBUG
   if( diffMemState.Difference( oldMemState, newMemState ) )
      TRACE( "Memory leaked!\n" );


"r norman" <> wrote in message

I have traced a memory leak problem to CAsyncSocket::Create(). Is
this a known problem? Is there a workaround/solution/fix? Here is
sample code:

 for (int i=0; i<m_nReopenCount; ++i) {
   CAsyncSocket *pAS = new CAsyncSocket;
   delete pAS;

Running this 1000 times uses up 1200 KBytes of memory, or just over 1
KByte per call. Commenting out the Create() leaves memory clean. (And
please don't complain about my bracketing style -- I like it.)

I have Visual Studio 2005 Professional version 8.0.

Incidentally, I also discovered that the call to Create() is not
re-entrant. My application involves connecting to some 10 to 20
external devices and my normal code creates a CWinThread to support
each socket, where the socket is created and destroyed only within
the thread routine. Creating all the threads and starting them up
simultaneously meant having multiple instances of
CAsyncSocket::Create() being called at the same time, crashing my
system (memory access faults). That one I found and fixed with
sentries. Now I am left with the memory leak.

The problem is that I have an rather intricate communication protocol
system all self contained so that adding a new hardware device simply
means creating a new instance of the whole works. It runs fine until
the external hardware goes haywire, in which case I destruct the whole
instance and start a new one which breaks and reconnects the socket
with a clean start and, most of the time, results in a good
connection; the external device resets itself through the disconnect.
One faulty device, though, generated thousand upon thousand of
disconnects over a number of days and, after a few hundred thousand of
these I my own system crashed due, I have now found out, to a lack of
memory caused by this leak.

My application must run essentially as an embedded system, unattended
week after week, month after month so I cannot tolerate a memory leak.
Does anybody know about this? Is there a simple clean way to force a
socket disconnection on a CAsyncSocket and then reconnect? My
application is the connect() end of the socket, not the listen() end.

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