Re: Threading Issue - Program hangs on Ctrl-C - URGENT PLZ

["jasvinder bajwa" <jasvinder_bajwa9@hotmail.com>]

Hi Amit,
In all your thread functions , you have statement do { } while(true) and 
trying to read from comm ports.
I guess you are looking for a graceful way of shutting down the threads.
i will suggest you to set a global variable something like timeToExit = 1;
change the condition to run the thread for ever to do { } while(timeToExit)
and when your applicaion catches Ctrl+C or any unwanted signal set the 
timeToExit to 0 which will cause all the threads to exit.

I guess it may solve the issue.
Thanks
Jas



>From: amit mishra <infoworldindia@yahoo.com>
>To: pthread <pthreads-win32@sources.redhat.com>
>Subject: Re: Threading Issue - Program hangs on Ctrl-C - URGENT PLZ
>Date: Fri, 17 Oct 2003 23:14:08 -0700 (PDT)
>
>Hi Ross,
>
>Thanks for the reply.
>I suppose the threads are not able to exit properly.
>Since all the threads are never going to terminate as
>it continues to read from respective COM ports, there
>should be some mechanism to end the thread gracefully.
>
>Could anyone give me sample code to test with for
>handling signals like Ctrl-C or to gracefully end the
>pthreads.
>
>Also, what should be the ideal mechanism for ending
>the threads when threads are continuosly running (i.e.
>its not going to terminate until some signal like
>Ctrl-C is given) ??
>
>Many Thanks
>Amit
>
>
>
>
>
>--- Ross Johnson <rpj@callisto.canberra.edu.au> wrote:
> > I don't have any direct experience in this area but
> > I believe exception
> > management in MT applications is tricky, so I
> > apologise in advance for
> > responding with questions.
> >
> > Questions:
> > What happens to the other threads when one thread
> > catches the exception
> > generated by ctrl-C?
> > What if the exception arrives while the thread holds
> > the mutex?
> >
> > Ross
> >
> > amit mishra wrote:
> >
> > >Hi,
> > >I had a simple serial port communication
> > application
> > >which uses pthread-win32 for threading.
> > >
> > >When the program exits, the application hangs and
> > the
> > >only way to recover is to restart the machine.
> > >
> > >I have debugged and the issue seems to be regarding
> > >thread handling or signal handling.
> > >
> > >Code snippet is given below for reference. Feel
> > free
> > >to ask for more information.
> > >
> > >Please reply asap.
> > >Many Thanks
> > >Amit
> > >--- CODE STARTS ------------------------------
> > >// all header files not shown
> > >
> > >#include "pthread.h"
> > >#include "signal.h"
> > >
> > >// three threads for each ports
> > >pthread_t t[3];
> > >int result = 0;
> > >int tid1, tid2, tid3;
> > >
> > >void* portOneFunc(void* arg);
> > >void* portTwoFunc(void* arg);
> > >void* portThreeFunc(void* arg);
> > >
> > >CDataOne* data1 = NULL;
> > >CDataTwo* data2 = NULL;
> > >CDataThree* data3 = NULL;
> > >
> > >// Custom Mutex class using pthread mutex
> > >CMyMutex myMutex;
> > >CWinApp theApp;
> > >
> > >//////////////////////////////////////////
> > >// Main
> > >//////////////////////////////////////////
> > >
> > >int _tmain(int argc, TCHAR* argv[], TCHAR* envp[])
> > >{
> > >// ---Initialize COMM Ports---
> > >CCommPort p1(RS_COM1);	// COM1
> > >CCommPort p2(RS_COM2);		// COM2
> > >CCommPort p3(RS_COM3);		// COM3
> > >
> > >// Init various Data Analyzers
> > >data1 = new CDataOne();
> > >data2 = new CDataTwo();
> > >data3 = new CDataThree();
> > >
> > >try {
> > >	// --------- Create Threads ------------
> > >	// Pthread Create
> > >	tid1 = pthread_create(
> > >		&t[0], NULL, portOneFunc, &p1);
> > >	tid2 = pthread_create(
> > >		&t[1], NULL, portTwoFunc, &p2);
> > >	tid3 = pthread_create(
> > >		&t[2], NULL, portThreeFunc, &p3);
> > >
> > >	// -------- Wait for Threads to complete ----
> > >	// Pthread Join
> > >	int ret = 0;
> > >
> > >	if (pthread_join(t[0], (void **) &result)) {
> > >		cout << "pthread join error" << endl;
> > >
> > >	}
> > >	if (pthread_join(t[1], (void **) &result)) {
> > >		cout << "pthread join error" << endl;
> > >	}
> > >	if (pthread_join(t[2], (void **) &result)) {
> > >		cout << "pthread join error" << endl;
> > >	}
> > >
> > >} PtW32CatchAll {
> > >	cerr << "ERROR : Thread Error" << endl;
> > >}
> > >
> > >delete data1;
> > >delete data2;
> > >delete data3;
> > >
> > >return 0;
> > >}
> > >
> > >
> > >//////////////////////////////////////////
> > >// Thread Functions
> > >//////////////////////////////////////////
> > >
> > >void* PortOneFunc(void* arg) {
> > >
> > >CCommPort *x_oPort1 = (CCommPort*)arg;
> > >
> > >try {
> > >   // Open Port with baudrate 4800
> > >   if (x_oPort1->Open(RS_4800)) {
> > >       	cout << "COM1 Opened" << endl;
> > >	do {
> > >	  // Get till terminating chars
> > >	  string str = x_oPort1->GetLine().c_str();
> > >myMutex.lock();				  // Append the data for further
> > >analysis
> > >	  data1->Append(str.c_str());
> > >	  myMutex.unlock();
> > >
> > >	} while(true);
> > >
> > >	  // Close the port
> > >	  x_oPort1->Close();
> > >	} else {
> > >	  cerr << "Error Opening COM 1 Port" << endl;
> > >	}
> > >} catch(...) {
> > >	cerr << "ERROR : Thread Exception" << endl;
> > >	//throw;
> > >}
> > >return (void*)true;
> > >}
> > >
> > >////////////////////////////////////////////
> > >void* PortTwoFunc(void* arg) {
> > >
> > >CCommPort *x_oPort2 = (CCommPort*)arg;
> > >
> > >try {
> > >	// Open Port
> > >	if (x_oPort2->Open(RS_1200)) {
> > >	  cout << "COM2 Opened" << endl;
> > >	  do {
> > >	     string str = x_oPort2->GetLine().c_str();
> > >	     myMutex.lock();
> > >	     data2->Append(str.c_str());
> > >	     myMutex.unlock();
> > >	  } while(true);
> > >	  x_oPort2->Close();
> > >	} else {
> > >   	cerr << "Error Opening COM 2 Port" << endl;
> > >	}
> > >} catch(...) {
> > >	cerr << "ERROR : Thread Exception" << endl;
> > >	//throw;
> > >}
> > >return (void*)true;
> > >}
> > >
> > >////////////////////////////////////////////
> > >void* PortThreeFunc(void* arg) {
> > >
> > >CCommPort *x_oPort3 = (CCommPort*)arg;
> > >
> > >try {
> > >   // Open Port
> > >   if (x_oPort3->Open(RS_1200)) {
> > >	cout << "COM3 Opened" << endl;
> > >	do {
> > >         string str = x_oPort3->GetLine().c_str();
> > >	 myMutex.lock();				 data3->Append(str.c_str());
> > >	 myMutex.unlock();
> > >	} while(true);
> > >	  x_oPort3->Close();
> > >   } else {
> > >	cerr << "Error Opening COM 3 Port" << endl;
> > >   }
> > >} catch(...) {
> > >   cerr << "ERROR : Thread Exception" << endl;
> > >   //throw;
> > >}
> > >
> > >return (void*)true;
> > >}
> > >-- CODE ENDS ------------------------------
> > >
> > >
> > >
> >
>=== message truncated ===
>
>
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