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/* This testcase is part of GDB, the GNU debugger.
Copyright 2021-2023 Free Software Foundation, Inc.
This program is free software; you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
the Free Software Foundation; either version 3 of the License, or
(at your option) any later version.
This program is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
GNU General Public License for more details.
You should have received a copy of the GNU General Public License
along with this program. If not, see <http://www.gnu.org/licenses/>. */
#define _GNU_SOURCE
#include <assert.h>
#include <pthread.h>
#include <stdlib.h>
#include <stdio.h>
#include <unistd.h>
#include <string.h>
#define THREADS 20
static volatile unsigned int global_var = 123;
/* Wrapper around pthread_create. */
static void
create_thread (pthread_t *child,
void *(*start_routine) (void *), void *arg)
{
int rc;
while ((rc = pthread_create (child, NULL, start_routine, arg)) != 0)
{
fprintf (stderr, "unexpected error from pthread_create: %s (%d)\n",
strerror (rc), rc);
sleep (1);
}
}
/* Data passed to threads on creation. This is allocated on the heap
and ownership transferred from parent to child. */
struct thread_arg
{
/* The thread's parent. */
pthread_t parent;
/* Whether to call pthread_join on the parent. */
int join_parent;
};
/* Entry point for threads. */
static void *
thread_fn (void *arg)
{
struct thread_arg *p = arg;
/* Passing no argument makes the thread exit immediately. */
if (p == NULL)
return NULL;
if (p->join_parent)
assert (pthread_join (p->parent, NULL) == 0);
/* Spawn a number of threads that exit immediately, and then join
them. The idea is to maximize the time window when we mostly
have threads exiting. */
{
pthread_t child[THREADS];
int i;
/* Passing no argument makes the thread exit immediately. */
for (i = 0; i < THREADS; i++)
create_thread (&child[i], thread_fn, NULL);
for (i = 0; i < THREADS; i++)
pthread_join (child[i], NULL);
}
/* Spawn a new thread that joins us, and exit. The idea here is to
not have any thread that stays around forever. */
{
pthread_t child;
p->parent = pthread_self ();
p->join_parent = 1;
create_thread (&child, thread_fn, p);
}
return NULL;
}
int
main (void)
{
int i;
for (i = 0; i < 4; i++)
{
struct thread_arg *p;
pthread_t child;
p = malloc (sizeof *p);
p->parent = pthread_self ();
/* Only join the parent once. */
if (i == 0)
p->join_parent = 1;
else
p->join_parent = 0;
create_thread (&child, thread_fn, p);
}
/* Exit the leader to make sure that we can access memory with the
leader gone. */
pthread_exit (NULL);
}
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