This is threads/prod_no_condvar.c, an example to accompany the book, The Linux Programming Interface.

This file is not printed in the book; it is a supplementary file for Chapter 30.

The source code file is copyright 2023, Michael Kerrisk, and is licensed under the GNU General Public License, version 3.

In the listing below, the names of Linux system calls and C library functions are hyperlinked to manual pages from the Linux man-pages project, and the names of functions implemented in the book are hyperlinked to the implementations of those functions.


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/* prod_no_condvar.c

   A simple POSIX threads producer-consumer example that doesn't use
   a condition variable.

   See also prod_condvar.c.
#include <time.h>
#include <pthread.h>
#include <stdbool.h>
#include "tlpi_hdr.h"

static pthread_mutex_t mtx = PTHREAD_MUTEX_INITIALIZER;

static int avail = 0;
static void *
producer(void *arg)
    int cnt = atoi((char *) arg);

    for (int j = 0; j < cnt; j++) {

        /* Code to produce a unit omitted */

        int s = pthread_mutex_lock(&mtx);
        if (s != 0)
            errExitEN(s, "pthread_mutex_lock");

        avail++;        /* Let consumer know another unit is available */

        s = pthread_mutex_unlock(&mtx);
        if (s != 0)
            errExitEN(s, "pthread_mutex_unlock");

    return NULL;
main(int argc, char *argv[])

    time_t t = time(NULL);

    int totRequired = 0;        /* Total number of units that all
                                   threads will produce */
    /* Create all threads */

    for (int j = 1; j < argc; j++) {
        totRequired += atoi(argv[j]);

        pthread_t tid;
        int s = pthread_create(&tid, NULL, producer, argv[j]);
        if (s != 0)
            errExitEN(s, "pthread_create");

    /* Use a polling loop to check for available units */

    int numConsumed = 0;        /* Total units so far consumed */
    bool done = false;

    for (;;) {
        int s = pthread_mutex_lock(&mtx);
        if (s != 0)
            errExitEN(s, "pthread_mutex_lock");

        while (avail > 0) {             /* Consume all available units */

            /* Do something with produced unit */

            numConsumed ++;
            printf("T=%ld: numConsumed=%d\n", (long) (time(NULL) - t),

            done = numConsumed >= totRequired;

        s = pthread_mutex_unlock(&mtx);
        if (s != 0)
            errExitEN(s, "pthread_mutex_unlock");

        if (done)

        /* Perhaps do other work here that does not require mutex lock */




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