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Full Discussion: Get the no. of threads spawned in a C program
Top Forums Programming Get the no. of threads spawned in a C program Post 302240399 by jim mcnamara on Thursday 25th of September 2008 04:35:39 PM
Old 09-25-2008
If you call pthread_create in a master thread or main program it is easy. This sit eh total numbers of threads created, not currently active threads
Code:
int thread_count=0;
...................
if(pthread_create(.....) == 0) thread_count++;

If "everybody" creates a thread, then you need to create a static mutex then a static integer variable in shared memory, initialize it to zero. Everybody calling pthread_create does this:
Code:
wait on mutex
get mutex & add one to the global counter;
release the mutex

pthreads have these basic calls (plus a lot of others)
Code:
create & destroy a mutex
      pthread_mutex_init(),
      pthread_mutex_destroy()
      PTHREAD_MUTEX_INITIALIZER is a macro to create a static mutex - probably what you want.

Lock/unlock a mutex.      

      pthread_mutex_lock(),
      pthread_mutex_trylock(),
      pthread_mutex_unlock()

that lets you play with mutexes. You will have to pass the mutex address to all of your threads or they cannot use it.
 

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LEARN ABOUT SUSE

xinitthreads

XInitThreads(3) 						  XLIB FUNCTIONS						   XInitThreads(3)

NAME

       XInitThreads, XLockDisplay, XUnlockDisplay - multi-threading support

SYNTAX

       Status XInitThreads(void);

       void XLockDisplay(Display *display);

       void XUnlockDisplay(Display *display);

ARGUMENTS

       display	 Specifies the connection to the X server.

DESCRIPTION

       The XInitThreads function initializes Xlib support for concurrent threads.  This function must be the first Xlib function a multi-threaded
       program calls, and it must complete before any other Xlib call is made.	This function returns a nonzero status if initialization was suc-
       cessful; otherwise, it returns zero.  On systems that do not support threads, this function always returns zero.

       It is only necessary to call this function if multiple threads might use Xlib concurrently.  If all calls to Xlib functions are protected
       by some other access mechanism (for example, a mutual exclusion lock in a toolkit or through explicit client programming), Xlib thread ini-
       tialization is not required.  It is recommended that single-threaded programs not call this function.

       The XLockDisplay function locks out all other threads from using the specified display.	Other threads attempting to use the display will
       block until the display is unlocked by this thread.  Nested calls to XLockDisplay work correctly; the display will not actually be unlocked
       until XUnlockDisplay has been called the same number of times as XLockDisplay.  This function has no effect unless Xlib was successfully
       initialized for threads using XInitThreads.

       The XUnlockDisplay function allows other threads to use the specified display again.  Any threads that have blocked on the display are
       allowed to continue.  Nested locking works correctly; if XLockDisplay has been called multiple times by a thread, then XUnlockDisplay must
       be called an equal number of times before the display is actually unlocked.  This function has no effect unless Xlib was successfully ini-
       tialized for threads using XInitThreads.

SEE ALSO

       Xlib - C Language X Interface

X Version 11							   libX11 1.3.2 						   XInitThreads(3)
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