Solved

reentry of functions through different threads

Posted on 1998-11-24
7
222 Views
Last Modified: 2010-04-01
I am reentring a function which creates a thread (inside the thread I am initializing & dealing with socket connection). As I said, this function is called a few times and is supposed to create a new thread each time.
When debbuging, I see that although I pass the lines in which the creating function is called, only the first thread is called (due to the first call to the function),
but no other threads are created.
Are there any restrictions on reentring functions?
Any restrictions on creating multiple threads that start with the same function?
Please give an example.
Thanks,
     Gilbert Chang
0
Comment
Question by:gilbert_chang
  • 4
  • 3
7 Comments
 
LVL 22

Expert Comment

by:nietod
ID: 1178597
How do you know no other threads are created?  How are you creating the threads?  Are you checking for error codes?  Do your realize that although a new thread may be created, it may not run right away.
0
 

Author Comment

by:gilbert_chang
ID: 1178598
I can view what threads are running while debugging using the icon that shows the debuggee's thread attributes in the VC++5.
I am creating threads using 'CreateThread'.
When looking for error codes, it seems like the threads are being created, but they dissapear quickly without doing their job...(running the function they should be started with)
If A thread does not run right away, how long can it take it? I am waiting for quite long periods of time (minutes!!).
Thanks.

0
 
LVL 22

Expert Comment

by:nietod
ID: 1178599
They may take on the order of a hundred milliseconds or so.  For some code designs (bad ones) that can be a problem.  Can you post the code you use to start the thread and the code of the started thread?
0
Announcing the Most Valuable Experts of 2016

MVEs are more concerned with the satisfaction of those they help than with the considerable points they can earn. They are the types of people you feel privileged to call colleagues. Join us in honoring this amazing group of Experts.

 

Author Comment

by:gilbert_chang
ID: 1178600
In the InitInstance of my CApp (was created by the MFC wizard):
mAppPtr = new App;
mAppPtr->StartIt();
mAppPtr->StartIt();
mAppPtr->StartIt();

then:

void App::StartIt()
{
HANDLE threadHandle;
DWORD threadID;

threadHandle = CreateThread (NULL ,0 ,Routine , this , 0 , &threadID);
}

Status _stdcall App::Routine( void * pvoid)
{
App * pseudo_this = (App *) pvoid;
pseudo_this->InitConnection();
DWORD myExitCode;
ExitThread(myExitCode );
return TRUE;
}

App::InitConnection()

{
//
// Here I create a socket + neccesary definitions, bind and try to connect
//
}

Thanks.
0
 
LVL 22

Accepted Solution

by:
nietod earned 50 total points
ID: 1178601
To begin with, one problem is that you cannot (should not) use CreateThread() from a C++ program.  A multi-threaded C++ program has a special version of the run-time library that is multi-thread compatible and provides procedures for startig a thread like beginthread().  These procedures use CreateThread(), to create the thread but do additional tasks, like initializing the  run-time library's information for the new thread.  However, in MFC, you shouldn't be using even those functions.  MFC provides threads features (that use beginthread) that should be used because they initialize MFC's information for the new thread.  You should be using a cWinThread object.  Look at cWinThread in the docs and then ask if you have questions.  I think things will work better when you switch to the cWinThread.  If not, let me know.
0
 
LVL 22

Expert Comment

by:nietod
ID: 1178602
So is this working for you?  Need more help?
0
 

Author Comment

by:gilbert_chang
ID: 1178603
Thanks a lot!!
0

Featured Post

Free Tool: Path Explorer

An intuitive utility to help find the CSS path to UI elements on a webpage. These paths are used frequently in a variety of front-end development and QA automation tasks.

One of a set of tools we're offering as a way of saying thank you for being a part of the community.

Question has a verified solution.

If you are experiencing a similar issue, please ask a related question

Introduction This article is the first in a series of articles about the C/C++ Visual Studio Express debugger.  It provides a quick start guide in using the debugger. Part 2 focuses on additional topics in breakpoints.  Lastly, Part 3 focuses on th…
Container Orchestration platforms empower organizations to scale their apps at an exceptional rate. This is the reason numerous innovation-driven companies are moving apps to an appropriated datacenter wide platform that empowers them to scale at a …
The viewer will learn how to user default arguments when defining functions. This method of defining functions will be contrasted with the non-default-argument of defining functions.
The viewer will be introduced to the technique of using vectors in C++. The video will cover how to define a vector, store values in the vector and retrieve data from the values stored in the vector.

860 members asked questions and received personalized solutions in the past 7 days.

Join the community of 500,000 technology professionals and ask your questions.

Join & Ask a Question