linux-c-programming.vger.kernel.org archive mirror
 help / color / mirror / Atom feed
* RE: Multithreading with C++
@ 2005-04-07 18:52 Huber, George K RDECOM CERDEC STCD SRI
  2005-04-07 19:01 ` Darío Mariani
  0 siblings, 1 reply; 7+ messages in thread
From: Huber, George K RDECOM CERDEC STCD SRI @ 2005-04-07 18:52 UTC (permalink / raw)
  To: Huber, George K RDECOM CERDEC STCD SRI; +Cc: linux prg

Eric wrote:

Did you compile with -lpthread and -D_REENTRANT? If I remeber correctly, this 
is something I had alot of trouble with when I started thread programming. 
Similiar error and everything. Compiled but the library calls weren't 
working. Make sure to include <pthread.h> too  ;)

yes included <pthread.h>, defined -D_REENTRANT and linked with -lpthread

I have written multi-threaded code in C, this is the first time that I have attempted 
to encapsulate a thread in a C++ object.  Must be missing something. :-(

George

^ permalink raw reply	[flat|nested] 7+ messages in thread
* RE: Multithreading with C++
@ 2005-04-08  6:47 Colovic (ext_evosoft) Aleksandar
  0 siblings, 0 replies; 7+ messages in thread
From: Colovic (ext_evosoft) Aleksandar @ 2005-04-08  6:47 UTC (permalink / raw)
  To: linux-c-programming

[-- Attachment #1: Type: text/plain, Size: 2661 bytes --]

Hi, 

try declaring threadfun as class static function : void* CThread::threadfun(void* arg)
Attached is the working code. I built it with make cthread.cpp LDFLAGS=-lpthread


Cheers



-----Original Message-----
From: linux-c-programming-owner@vger.kernel.org [mailto:linux-c-programming-owner@vger.kernel.org]On Behalf Of Huber, George K RDECOM CERDEC STCD SRI
Sent: Donnerstag, 7. April 2005 19:02
To: linux-c-programming@vger.kernel.org
Subject: Multithreading with C++


All,

This may be a little off topic, but I though I would try here first.

I am writting a multi-threaded program and would like to have each 
thread `managed' by a class.  I have attempted to do this like this,
using the pthreads library:

<code>
====================begin cthread.h

class CThread
{
public:
    CThread(void*);
    ~CThread();

    ....

private:
    static CThread*     m_pThis;
    pthread_t             m_tid;
    static void*           threadfun(void*);

   ....
}

==================== begin cthread.cpp

CThread*  CThread::m_pThis = NULL;

CThread::CThread(void* arg)
{
    int      ret;

    m_pThis = this;
    if(0 != (ret = pthread_create(&m_tid, NULL, threadfun, arg)))
    {
         fprintf(stderr, "Thread creation failed");
   }
}   

void*  threadfun(void* arg)
{
     printf("Starting thread\n");
     ....
}

</code>

The code compiles without warnings or errors, except when I try and 
run the application I get a segmentation fault at the pthread_create.  
Trying to run under GDB, I am able to examine the value of the 
variables and they seem consisten with what I would expect

// stop on the pthread_create line in the constructor...

(gdb) print m_pThis
$1 = (CThread*) 0xfee756b0
(gdb) print this
$2 = (CThread*0xfee756b0
(gdb) print m_tid
$3 = 134514818               // to be expected because I have not initialized m_tid yet
(gdb) print &m_tid
$4 = (pthread_t*)0xfee756d8
(gdb) print threadfun
$5=&CThread::threadfun(void*)

// attempt the pthread_create line ....

Program received signal SIGSEGV, Segmenatation fault
0x0000000 in ?? ()
(gdb) where 
#0 0x00000000 in ?? ( )
#1 0x0804a6bb in CThread (this=0xfee756b0, args=0x0) at ....
#2 0x08049aad in daemon_main(argc=3, argv=0xfeec42d4) at ....
#3 0x08049193 in main(argc=3, argv=0xfeec42d3) at main.cpp: 83

Any idea on what is going on, or how to fix?

Thanks, 
George Huber

-
To unsubscribe from this list: send the line "unsubscribe linux-c-programming" in
the body of a message to majordomo@vger.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html

[-- Attachment #2: cthread.h --]
[-- Type: application/octet-stream, Size: 245 bytes --]

#include "pthread.h"
#include "stdio.h"

class CThread
{
public:
    CThread(void*);
    ~CThread();


private:
    static CThread*     m_pThis;
    pthread_t             m_tid;
    static void*           threadfun(void*);

};


[-- Attachment #3: cthread.cpp --]
[-- Type: application/octet-stream, Size: 435 bytes --]

#include "cthread.h"


CThread* CThread::m_pThis = NULL;

CThread::~CThread() {}
CThread::CThread(void* arg)
{
    int      ret;

    m_pThis = this;
    if(0 != (ret = pthread_create(&m_tid, NULL, threadfun, arg)))
    {
         fprintf(stderr, "Thread creation failed");
   }
}   

void* CThread::threadfun(void* arg)
{
     printf("Starting thread\n");
}

int main(int argc, char** argv)
{
	CThread ct(0);
	
	return 0;
}

^ permalink raw reply	[flat|nested] 7+ messages in thread
* Multithreading with C++
@ 2005-04-07 17:02 Huber, George K RDECOM CERDEC STCD SRI
  2005-04-07 16:36 ` Eric Bambach
  2005-04-08  2:01 ` Ron Michael Khu
  0 siblings, 2 replies; 7+ messages in thread
From: Huber, George K RDECOM CERDEC STCD SRI @ 2005-04-07 17:02 UTC (permalink / raw)
  To: linux-c-programming

All,

This may be a little off topic, but I though I would try here first.

I am writting a multi-threaded program and would like to have each 
thread `managed' by a class.  I have attempted to do this like this,
using the pthreads library:

<code>
====================begin cthread.h

class CThread
{
public:
    CThread(void*);
    ~CThread();

    ....

private:
    static CThread*     m_pThis;
    pthread_t             m_tid;
    static void*           threadfun(void*);

   ....
}

==================== begin cthread.cpp

CThread*  CThread::m_pThis = NULL;

CThread::CThread(void* arg)
{
    int      ret;

    m_pThis = this;
    if(0 != (ret = pthread_create(&m_tid, NULL, threadfun, arg)))
    {
         fprintf(stderr, "Thread creation failed");
   }
}   

void*  threadfun(void* arg)
{
     printf("Starting thread\n");
     ....
}

</code>

The code compiles without warnings or errors, except when I try and 
run the application I get a segmentation fault at the pthread_create.  
Trying to run under GDB, I am able to examine the value of the 
variables and they seem consisten with what I would expect

// stop on the pthread_create line in the constructor...

(gdb) print m_pThis
$1 = (CThread*) 0xfee756b0
(gdb) print this
$2 = (CThread*0xfee756b0
(gdb) print m_tid
$3 = 134514818               // to be expected because I have not initialized m_tid yet
(gdb) print &m_tid
$4 = (pthread_t*)0xfee756d8
(gdb) print threadfun
$5=&CThread::threadfun(void*)

// attempt the pthread_create line ....

Program received signal SIGSEGV, Segmenatation fault
0x0000000 in ?? ()
(gdb) where 
#0 0x00000000 in ?? ( )
#1 0x0804a6bb in CThread (this=0xfee756b0, args=0x0) at ....
#2 0x08049aad in daemon_main(argc=3, argv=0xfeec42d4) at ....
#3 0x08049193 in main(argc=3, argv=0xfeec42d3) at main.cpp: 83

Any idea on what is going on, or how to fix?

Thanks, 
George Huber


^ permalink raw reply	[flat|nested] 7+ messages in thread
end of thread, other threads:[~2005-04-08  6:47 UTC | newest]

Thread overview: 7+ messages (download: mbox.gz follow: Atom feed
-- links below jump to the message on this page --
2005-04-07 18:52 Multithreading with C++ Huber, George K RDECOM CERDEC STCD SRI
2005-04-07 19:01 ` Darío Mariani
     [not found]   ` <fde202080504071322520de47@mail.gmail.com>
2005-04-07 20:26     ` Sandro Dangui
  -- strict thread matches above, loose matches on Subject: below --
2005-04-08  6:47 Colovic (ext_evosoft) Aleksandar
2005-04-07 17:02 Huber, George K RDECOM CERDEC STCD SRI
2005-04-07 16:36 ` Eric Bambach
2005-04-08  2:01 ` Ron Michael Khu

This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).