The normal threaded way to do what is suggested is to create a monitor thread for notification and use pthread_cond primitives for the synchronization.
Example code follows.
Code:
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <pthread.h>
#include <unistd.h>
#include <time.h>
#define MAXTHREAD 5
#define FIRE 20
typedef struct msg {
pthread_t tnum;
} M;
/*global*/
pthread_cond_t alert = PTHREAD_COND_INITIALIZER;
pthread_mutex_t alertmtx = PTHREAD_MUTEX_INITIALIZER;
static M foo;
void *monitor(void *);
void *do_random(void *);
#define liveloop() {while (1) {sleep(1);}}
int main(void) {
int y = 0;
pthread_t monthread;
pthread_t t[MAXTHREAD];
srand(time(NULL));
if (pthread_create(&monthread,NULL,monitor,NULL) != 0) {perror("pthread_create()"); return -1;}
while (y < MAXTHREAD) {
pthread_create(&t[y],NULL,do_random,NULL);
y++;
}
liveloop();
}
void *monitor(void *arg) {
pthread_mutex_lock(&alertmtx);
while (1) {
pthread_cond_wait(&alert,&alertmtx);
printf("Received notification from thread id: %d.\n",foo.tnum);
}
pthread_mutex_unlock(&alertmtx);
}
void *do_random(void *arg) {
int r;
time_t beg, end;
pthread_detach(pthread_self());
r = (int)(1 + rand() % FIRE);
end = beg = time(NULL);
end += r;
for (;;) {
while (end > beg) {
beg = time(NULL);
sleep(1);
}
pthread_mutex_lock(&alertmtx);
foo.tnum = pthread_self();
pthread_cond_signal(&alert);
end += r;
pthread_mutex_unlock(&alertmtx);
}
}
Except, instead of liveloop in main(), you'd join on the monitoring thread which would exit the process group in case of calamitous error.
Last edited by ramen_noodle; 09-08-2008 at 05:08 PM..
Hello,
i have 2 questions:
1. Can I get the current memory usage of a thread?
2. Can I use a member-function as (void*)(*)(void*) method to create a new thread with "pthread_create(...)"??
I would be happy about any suggestion.
Regards,
Rolf (2 Replies)
Hi all!
I am implementing an http server in c++ using the posix thread, but i am having a memory leak and i cannot find the reason.
I have already commented out the section that initializes the threads and i found out, the problem is when i initialize/run the threads.
In the threads i have... (1 Reply)
I am facing a strange error while creating posix threads:
Given below are two snippets of code, the first one works whereas the second one gives a garbage value in the output.
Snippet 1
This works:
--------------
int *threadids;
threadids = (int *) malloc (num_threads * sizeof(int));
... (4 Replies)
i am creating threads in my program using the POSIX interface.
when the thread starts executing i run out of memory and get a core dump.
i have tried to increase the threads stack size using pthread_attr_setstacksize, but of no use since i guess the dynamic memory is allocated on the heap and... (1 Reply)
Hi All,
I have scenario where my callback function data_update() can be called anytime. I have written the function data_update() such that it will create detached thread for processing the data sent to this function.
data_update()
{
pthread_attr_t attr_thread;
... (1 Reply)
Hi All,
I am creating detached threads using pthread_create(). As we know, we need to pass the thread attribute structure as an argument to the pthread_Create() API.
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is there a better way to check if a port is active on linux and sunos systems?
this is currently what I'm using in my script:
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I want to create a program that creates 2 child process, and each of them creates 2 threads, and each thread prints its thread id. I0ve allread done that the outuput isn't the outuput i want.
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2
$:
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Discussion started by: pharaoh
3 Replies
LEARN ABOUT CENTOS
pthread_detach
PTHREAD_DETACH(3) Linux Programmer's Manual PTHREAD_DETACH(3)NAME
pthread_detach - detach a thread
SYNOPSIS
#include <pthread.h>
int pthread_detach(pthread_t thread);
Compile and link with -pthread.
DESCRIPTION
The pthread_detach() function marks the thread identified by thread as detached. When a detached thread terminates, its resources are
automatically released back to the system without the need for another thread to join with the terminated thread.
Attempting to detach an already detached thread results in unspecified behavior.
RETURN VALUE
On success, pthread_detach() returns 0; on error, it returns an error number.
ERRORS
EINVAL thread is not a joinable thread.
ESRCH No thread with the ID thread could be found.
CONFORMING TO
POSIX.1-2001.
NOTES
Once a thread has been detached, it can't be joined with pthread_join(3) or be made joinable again.
A new thread can be created in a detached state using pthread_attr_setdetachstate(3) to set the detached attribute of the attr argument of
pthread_create(3).
The detached attribute merely determines the behavior of the system when the thread terminates; it does not prevent the thread from being
terminated if the process terminates using exit(3) (or equivalently, if the main thread returns).
Either pthread_join(3) or pthread_detach() should be called for each thread that an application creates, so that system resources for the
thread can be released. (But note that the resources of all threads are freed when the process terminates.)
EXAMPLE
The following statement detaches the calling thread:
pthread_detach(pthread_self());
SEE ALSO pthread_attr_setdetachstate(3), pthread_cancel(3), pthread_create(3), pthread_exit(3), pthread_join(3), pthreads(7)COLOPHON
This page is part of release 3.53 of the Linux man-pages project. A description of the project, and information about reporting bugs, can
be found at http://www.kernel.org/doc/man-pages/.
Linux 2008-11-27 PTHREAD_DETACH(3)