gdb/testsuite/gdb.threads/attach-many-short-lived-threads.c

   1 /* This testcase is part of GDB, the GNU debugger.
   2
   3    Copyright 2014-2024 Free Software Foundation, Inc.
   4
   5    This program is free software; you can redistribute it and/or modify
   6    it under the terms of the GNU General Public License as published by
   7    the Free Software Foundation; either version 3 of the License, or
   8    (at your option) any later version.
   9
  10    This program is distributed in the hope that it will be useful,
  11    but WITHOUT ANY WARRANTY; without even the implied warranty of
  12    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  13    GNU General Public License for more details.
  14
  15    You should have received a copy of the GNU General Public License
  16    along with this program.  If not, see <http://www.gnu.org/licenses/>.  */
  17
  18 #define _GNU_SOURCE
  19 #include <assert.h>
  20 #include <pthread.h>
  21 #include <stdlib.h>
  22 #include <stdio.h>
  23 #include <unistd.h>
  24 #include <string.h>
  25
  26 pthread_t main_thread;
  27 pthread_attr_t detached_attr;
  28 pthread_attr_t joinable_attr;
  29
  30 /* Number of threads we'll create of each variant
  31    (joinable/detached).  */
  32 int n_threads = 50;
  33
  34 /* Mutex used to hold creating detached threads.  */
  35 pthread_mutex_t dthrds_create_mutex;
  36
  37 /* Wrapper for pthread_create.   */
  38
  39 void
  40 create_thread (pthread_attr_t *attr,
  41                void *(*start_routine) (void *), void *arg)
  42 {
  43   pthread_t child;
  44   int rc;
  45
  46   while ((rc = pthread_create (&child, attr, start_routine, arg)) != 0)
  47     {
  48       fprintf (stderr, "unexpected error from pthread_create: %s (%d)\n",
  49                strerror (rc), rc);
  50       sleep (1);
  51     }
  52 }
  53
  54 void
  55 break_fn (void)
  56 {
  57 }
  58
  59 /* Data passed to joinable threads on creation.  This is allocated on
  60    the heap and ownership transferred from parent to child.  (We do
  61    this because it's not portable to cast pthread_t to pointer.)  */
  62
  63 struct thread_arg
  64 {
  65   pthread_t parent;
  66 };
  67
  68 /* Entry point for joinable threads.  These threads first join their
  69    parent before spawning a new child (and exiting).  The parent's tid
  70    is passed as pthread_create argument, encapsulated in a struct
  71    thread_arg object.  */
  72
  73 void *
  74 joinable_fn (void *arg)
  75 {
  76   struct thread_arg *p = arg;
  77
  78   pthread_setname_np (pthread_self (), "joinable");
  79
  80   if (p->parent != main_thread)
  81     assert (pthread_join (p->parent, NULL) == 0);
  82
  83   p->parent = pthread_self ();
  84
  85   create_thread (&joinable_attr, joinable_fn, p);
  86
  87   break_fn ();
  88
  89   return NULL;
  90 }
  91
  92 /* Entry point for detached threads.  */
  93
  94 void *
  95 detached_fn (void *arg)
  96 {
  97   pthread_setname_np (pthread_self (), "detached");
  98
  99   /* This should throttle threads a bit in case we manage to spawn
 100      threads faster than they exit.  */
 101   pthread_mutex_lock (&dthrds_create_mutex);
 102
 103   create_thread (&detached_attr, detached_fn, NULL);
 104
 105   /* Note this is called before the mutex is unlocked otherwise in
 106      non-stop mode, when the breakpoint is hit we'd keep spawning more
 107      threads forever while the old threads stay alive (stopped in the
 108      breakpoint).  */
 109   break_fn ();
 110
 111   pthread_mutex_unlock (&dthrds_create_mutex);
 112
 113   return NULL;
 114 }
 115
 116 /* Allow for as much timeout as DejaGnu wants, plus a bit of
 117    slack.  */
 118 #define SECONDS (TIMEOUT + 20)
 119
 120 /* We'll exit after this many seconds.  */
 121 unsigned int seconds_left = SECONDS;
 122
 123 /* GDB sets this whenever it's about to start a new detach/attach
 124    sequence.  We react by resetting the seconds left counter.  */
 125 volatile int again = 0;
 126
 127 int
 128 main (int argc, char *argv[])
 129 {
 130   int i;
 131
 132   if (argc > 1)
 133     n_threads = atoi (argv[1]);
 134
 135   pthread_mutex_init (&dthrds_create_mutex, NULL);
 136
 137   pthread_attr_init (&detached_attr);
 138   pthread_attr_setdetachstate (&detached_attr, PTHREAD_CREATE_DETACHED);
 139   pthread_attr_init (&joinable_attr);
 140   pthread_attr_setdetachstate (&joinable_attr, PTHREAD_CREATE_JOINABLE);
 141
 142   main_thread = pthread_self ();
 143
 144   /* Spawn the initial set of test threads.  Some threads are
 145      joinable, others are detached.  This exercises different code
 146      paths in the runtime.  */
 147   for (i = 0; i < n_threads; ++i)
 148     {
 149       struct thread_arg *p;
 150
 151       p = malloc (sizeof *p);
 152       p->parent = main_thread;
 153       create_thread (&joinable_attr, joinable_fn, p);
 154
 155       create_thread (&detached_attr, detached_fn, NULL);
 156     }
 157
 158   /* Exit after a while if GDB is gone/crashes.  But wait long enough
 159      for one attach/detach sequence done by the .exp file.  */
 160   while (--seconds_left > 0)
 161     {
 162       sleep (1);
 163
 164       if (again)
 165         {
 166           /* GDB should be reattaching soon.  Restart the timer.  */
 167           again = 0;
 168           seconds_left = SECONDS;
 169         }
 170     }
 171
 172   printf ("timeout, exiting\n");
 173   return 0;
 174 }