1PTHREAD_GETATTR_DEFAULT_NP(3L)inux Programmer's ManuPaTlHREAD_GETATTR_DEFAULT_NP(3)
2
6 pthread_getattr_default_np, pthread_setattr_default_np, - get or set
7 default thread-creation attributes
8
10 #define _GNU_SOURCE /* See feature_test_macros(7) */
11 #include <pthread.h>
12 int pthread_getattr_default_np(pthread_attr_t *attr);
14 int pthread_setattr_default_np(const pthread_attr_t *attr);
15 Compile and link with -pthread.
17
19 The pthread_setattr_default_np() function sets the default attributes
20 used for creation of a new thread—that is, the attributes that are used
21 when pthread_create(3) is called with a second argument that is NULL.
22 The default attributes are set using the attributes supplied in *attr,
23 a previously initialized thread attributes object. Note the following
24 details about the supplied attributes object:
25 * The attribute settings in the object must be valid.
27 * The stack address attribute must not be set in the object.
29 * Setting the stack size attribute to zero means leave the default
31 stack size unchanged.
32 The pthread_getattr_default_np() function initializes the thread at‐
34 tributes object referred to by attr so that it contains the default at‐
35 tributes used for thread creation.
36
38 EINVAL (pthread_setattr_default_np()) One of the attribute settings in
39 attr is invalid, or the stack address attribute is set in attr.
40 ENOMEM (pthread_setattr_default_np()) Insufficient memory.
42
44 These functions are available in glibc since version 2.18.
45
47 For an explanation of the terms used in this section, see at‐
48 tributes(7).
49 ┌────────────────────────────────────────────┬───────────────┬─────────┐
51 │Interface │ Attribute │ Value │
52 ├────────────────────────────────────────────┼───────────────┼─────────┤
53 │pthread_getattr_default_np(), │ Thread safety │ MT-Safe │
54 │pthread_setattr_default_np() │ │ │
55 └────────────────────────────────────────────┴───────────────┴─────────┘
56
58 These functions are nonstandard GNU extensions; hence the suffix "_np"
59 (nonportable) in their names.
60
62 The program below uses pthread_getattr_default_np() to fetch the de‐
63 fault thread-creation attributes and then displays various settings
64 from the returned thread attributes object. When running the program,
65 we see the following output:
66 $ ./a.out
68 Stack size: 8388608
69 Guard size: 4096
70 Scheduling policy: SCHED_OTHER
71 Scheduling priority: 0
72 Detach state: JOINABLE
73 Inherit scheduler: INHERIT
74 Program source
76 #define _GNU_SOURCE
78 #include <pthread.h>
79 #include <stdio.h>
80 #include <stdlib.h>
81 #include <errno.h>
82 #define errExitEN(en, msg) \
84 do { errno = en; perror(msg); \
85 exit(EXIT_FAILURE); } while (0)
86 static void
88 display_pthread_attr(pthread_attr_t *attr)
89 {
90 int s;
91 size_t stacksize;
92 size_t guardsize;
93 int policy;
94 struct sched_param schedparam;
95 int detachstate;
96 int inheritsched;
97 s = pthread_attr_getstacksize(attr, &stacksize);
99 if (s != 0)
100 errExitEN(s, "pthread_attr_getstacksize");
101 printf("Stack size: %zd\n", stacksize);
102 s = pthread_attr_getguardsize(attr, &guardsize);
104 if (s != 0)
105 errExitEN(s, "pthread_attr_getguardsize");
106 printf("Guard size: %zd\n", guardsize);
107 s = pthread_attr_getschedpolicy(attr, &policy);
109 if (s != 0)
110 errExitEN(s, "pthread_attr_getschedpolicy");
111 printf("Scheduling policy: %s\n",
112 (policy == SCHED_FIFO) ? "SCHED_FIFO" :
113 (policy == SCHED_RR) ? "SCHED_RR" :
114 (policy == SCHED_OTHER) ? "SCHED_OTHER" : "[unknown]");
115 s = pthread_attr_getschedparam(attr, &schedparam);
117 if (s != 0)
118 errExitEN(s, "pthread_attr_getschedparam");
119 printf("Scheduling priority: %d\n", schedparam.sched_priority);
120 s = pthread_attr_getdetachstate(attr, &detachstate);
122 if (s != 0)
123 errExitEN(s, "pthread_attr_getdetachstate");
124 printf("Detach state: %s\n",
125 (detachstate == PTHREAD_CREATE_DETACHED) ? "DETACHED" :
126 (detachstate == PTHREAD_CREATE_JOINABLE) ? "JOINABLE" :
127 "???");
128 s = pthread_attr_getinheritsched(attr, &inheritsched);
130 if (s != 0)
131 errExitEN(s, "pthread_attr_getinheritsched");
132 printf("Inherit scheduler: %s\n",
133 (inheritsched == PTHREAD_INHERIT_SCHED) ? "INHERIT" :
134 (inheritsched == PTHREAD_EXPLICIT_SCHED) ? "EXPLICIT" :
135 "???");
136 }
137 int
139 main(int argc, char *argv[])
140 {
141 int s;
142 pthread_attr_t attr;
143 s = pthread_getattr_default_np(&attr);
145 if (s != 0)
146 errExitEN(s, "pthread_getattr_default_np");
147 display_pthread_attr(&attr);
149 exit(EXIT_SUCCESS);
151 }
152
154 pthread_attr_getaffinity_np(3), pthread_attr_getdetachstate(3),
155 pthread_attr_getguardsize(3), pthread_attr_getinheritsched(3),
156 pthread_attr_getschedparam(3), pthread_attr_getschedpolicy(3),
157 pthread_attr_getscope(3), pthread_attr_getstack(3),
158 pthread_attr_getstackaddr(3), pthread_attr_getstacksize(3),
159 pthread_attr_init(3), pthread_create(3), pthreads(7)
160
162 This page is part of release 5.12 of the Linux man-pages project. A
163 description of the project, information about reporting bugs, and the
164 latest version of this page, can be found at
165 https://www.kernel.org/doc/man-pages/.
166Linux 2021-03-22 PTHREAD_GETATTR_DEFAULT_NP(3)