Thanks for you reply. Actually when we commented all the calls related to
"Joseph M. Newcomer" wrote:
See below...
On Wed, 7 May 2008 02:11:00 -0700, App shows memory leak on some machines.
<Appshowsmemoryleakonsomemachines@discussions.microsoft.com> wrote:
Actually I've originally used AfxBeginThread() function to launch thread and
just a return statement while exiting thread. And since I was getting handle
leak along with memory leak, I tried using CloseHandle() in the previously
mentioned way. After this change I found no difference in app's behavior.
I again revert back to original code where I've used a return statement in
the top level thread function. Still I can find same behavior (handle +
memory leak).
I'll like to add some more points here-
-I am launching only one thread from main thread.
Lets say ThreadFirst is launched by main thread. Now, all other threads are
getting launched by ThreadFirst.
It's required since main thread needs to do other task.
-Again there is a critical section (semaphore) in thread function. Many
threads are keep on hanging at the start of critical section waiting for
others threads to leave.
****
I suspect you are confused. A CRITICAL_SECTION is a very efficient low-level
synchronization primitive. A mutex is a considerably less efficient synchronization
primitive. A semaphore is something completely different, and fulfills the purposes of a
semaphore (a counted exclusion object) and has little to do with mutual exclusion of
multiple threads. So when you say "critical section (semaphore)" I become suspicious,
because semaphores would not be appropriate here.
And yes, if you have a synchronization object, and you have high contention, you are
likely to have a lot of threads hanging.
Some rules:
Don't use synchronization. Design your code so there is no need for
concurrent access
Lock data, not code
Lock the smallest possible amount of data for the shortest possible time
In the absence of any code example showing the locking, it is hard to guess what you might
have done, but the most likely cause is that you have violated one or more of the above
rules.
Locking is done when threads rub together. That means there is friction. And just like
in mechanical systems, friction generates heat and wastes energy. I tend to view
synchronization as something that should be avoided by making sure threads are not
actually rubbing. See my essay "The Best Synchronization is No Synchronization" on my MVP
Tips site. Every once in a while, you need concurrent access, but the more I work with
threads, the less I do it.
joe
****
Can it create any problem??
Thanks,
Digvijay
"Nick Schultz" wrote:
Use Process Explorer from www.sysinternals.com . It is free and is MUCH
better than Task Manager, you can double click on a process and get very
detailed information, including a list of threads and memory usage. It also
shows processes in a tree format rather than just a flat list...overall its
a better tool.
Go to the Options menu and select "Replace Task Manager" and Process
Explorer will pop up whenever you press CTRL+ALT+DEL.
Nick
"App shows memory leak on some machines."
<Appshowsmemoryleakonsomemachines@discussions.microsoft.com> wrote in
message news:91870733-F651-4E90-A5E7-88CB6170E89D@microsoft.com...
Thank you Joseph for your reply.
I've used AfxBeginThread() function to launch thread and subsequently
AfxEndThread() to end it.
I tried using CloseHandle() and checked its return value, also checked
return value for GetLastError(), to make sure that handle is getting
closed.
Return values were as expected. But, it made no difference in behaviour of
exe.
This part of code looks like
//--------------------------------
CWinThread* ThPtr = AfxBeginThread(..);
bool b = ::CloseHandle(ThPtr->m_hThread);
int n = GetLastError();
thread function:
ThreadFunc()
{
.
.
.
AfxEndThread();
returb bRet;
}
//--------------------------------
I've used socket and DB calls inside thread function. For DB
communication,
I've used 'msado15.dll'.
I'll like to know, in which cases application will behave differently (in
terms of memory leaks) on different machine?
Thanks,
Digvijay
"Joseph M. Newcomer" wrote:
It is FAR more likely that what happened is that you are failing to close
the thread
handle of the thread, resulting in a leakage of thread stacks. Are you
certain every
thread handle is being closed?
The task manager may suggest that memory usage is increasing (it is one
of the few valid
reports about memory it is actually capable of), but you need to rule out
lots of other
explanations before pointing to MDAC (not that it might not be the cause,
but the most
common error I've found in multithreaded leaks is stack leakage). I
would suggest
downloading the free App Verifier from the Microsoft site and turning on
all memory
management options.
joe
On Fri, 2 May 2008 07:48:02 -0700, Prashant
<Prashant@discussions.microsoft.com> wrote:
The application is a multithreaded exe involving socket communication.
The
memory usage in task manager increases when exe is running. It never
comes
down. In other words, for each thread it increases and never comes down
even
after that thread dies.
Thanks,
Digvijay
"Joseph M. Newcomer" wrote:
How do you detect that there is a memory leak? You assert this is
happening without
explaining why you think it is so.
joe
On Thu, 1 May 2008 05:11:01 -0700, App shows memory leak on some
machines. <App shows
memory leak on some machines.@discussions.microsoft.com> wrote:
Hi,
My application (developed in VC++) is running fine on most of the
machines(without any memory leak). But, it is showing memory leaks on
production machine. Even on development side it is showing memory
leaks on
few machine. Why it is so?
Hardware configuration of these machines are different. But, I think
this
difference should not create any memory leak in application.
My application is using database communication and socket
communication APIs.
Is there any relation bet Hardware configuration and MDAC
version?????
Is MDAC 2.82.3959.0 having memory leak problems??
I've checked my code several times with different APIs and tools, but
it has
no memory leak. Please help me solving the problem. I've tried to
solve
problem in many ways for a long time, but not getting any output.
MDAC versions on these machines are mentioned below.
Development machine : 2.81.1128.0
Production machines : 2.82.3959.0
OS : XP SP2, Windows 2003 server
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
Joseph M. Newcomer [MVP]
email: newcomer@flounder.com
Web: http://www.flounder.com
MVP Tips: http://www.flounder.com/mvp_tips.htm