1PTHREAD_GETATTR_DEFAULT_NP(3L)inux Programmer's ManuPaTlHREAD_GETATTR_DEFAULT_NP(3)
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NAME

6       pthread_getattr_default_np,  pthread_setattr_default_np,  -  get or set
7       default thread-creation attributes
8

SYNOPSIS

10       #define _GNU_SOURCE             /* See feature_test_macros(7) */
11       #include <pthread.h>
12
13       int pthread_getattr_default_np(pthread_attr_t *attr);
14       int pthread_setattr_default_np(pthread_attr_t *attr);
15
16       Compile and link with -pthread.
17

DESCRIPTION

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
26       *  The attribute settings in the object must be valid.
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28       *  The stack address attribute must not be set in the object.
29
30       *  Setting  the  stack  size  attribute to zero means leave the default
31          stack size unchanged.
32
33       The  pthread_getattr_default_np()  function  initializes   the   thread
34       attributes  object  referred to by attr so that it contains the default
35       attributes used for thread creation.
36

ERRORS

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
41       ENOMEM (pthread_setattr_default_np()) Insufficient memory.
42

VERSIONS

44       These functions are available in glibc since version 2.18.
45

ATTRIBUTES

47       For   an   explanation   of   the  terms  used  in  this  section,  see
48       attributes(7).
49
50       ┌───────────────────────────────┬───────────────┬─────────┐
51Interface                      Attribute     Value   
52       ├───────────────────────────────┼───────────────┼─────────┤
53pthread_getattr_default_np(),  │ Thread safety │ MT-Safe │
54pthread_setattr_default_np()   │               │         │
55       └───────────────────────────────┴───────────────┴─────────┘

CONFORMING TO

57       These  functions are nonstandard GNU extensions; hence the suffix "_np"
58       (nonportable) in their names.
59

EXAMPLES

61       The  program  below  uses  pthread_getattr_default_np()  to  fetch  the
62       default  thread-creation  attributes and then displays various settings
63       from the returned thread attributes object.  When running the  program,
64       we see the following output:
65
66           $ ./a.out
67           Stack size:          8388608
68           Guard size:          4096
69           Scheduling policy:   SCHED_OTHER
70           Scheduling priority: 0
71           Detach state:        JOINABLE
72           Inherit scheduler:   INHERIT
73
74   Program source
75
76       #define _GNU_SOURCE
77       #include <pthread.h>
78       #include <stdio.h>
79       #include <stdlib.h>
80       #include <errno.h>
81
82       #define errExitEN(en, msg) \
83                               do { errno = en; perror(msg); \
84                                    exit(EXIT_FAILURE); } while (0)
85
86       static void
87       display_pthread_attr(pthread_attr_t *attr)
88       {
89           int s;
90           size_t stacksize;
91           size_t guardsize;
92           int policy;
93           struct sched_param schedparam;
94           int detachstate;
95           int inheritsched;
96
97           s = pthread_attr_getstacksize(attr, &stacksize);
98           if (s != 0)
99               errExitEN(s, "pthread_attr_getstacksize");
100           printf("Stack size:          %zd\n", stacksize);
101
102           s = pthread_attr_getguardsize(attr, &guardsize);
103           if (s != 0)
104               errExitEN(s, "pthread_attr_getguardsize");
105           printf("Guard size:          %zd\n", guardsize);
106
107           s = pthread_attr_getschedpolicy(attr, &policy);
108           if (s != 0)
109               errExitEN(s, "pthread_attr_getschedpolicy");
110           printf("Scheduling policy:   %s\n",
111                   (policy == SCHED_FIFO) ? "SCHED_FIFO" :
112                   (policy == SCHED_RR) ? "SCHED_RR" :
113                   (policy == SCHED_OTHER) ? "SCHED_OTHER" : "[unknown]");
114
115           s = pthread_attr_getschedparam(attr, &schedparam);
116           if (s != 0)
117               errExitEN(s, "pthread_attr_getschedparam");
118           printf("Scheduling priority: %d\n", schedparam.sched_priority);
119
120           s = pthread_attr_getdetachstate(attr, &detachstate);
121           if (s != 0)
122               errExitEN(s, "pthread_attr_getdetachstate");
123           printf("Detach state:        %s\n",
124                   (detachstate == PTHREAD_CREATE_DETACHED) ? "DETACHED" :
125                   (detachstate == PTHREAD_CREATE_JOINABLE) ? "JOINABLE" :
126                   "???");
127
128           s = pthread_attr_getinheritsched(attr, &inheritsched);
129           if (s != 0)
130               errExitEN(s, "pthread_attr_getinheritsched");
131           printf("Inherit scheduler:   %s\n",
132                   (inheritsched == PTHREAD_INHERIT_SCHED) ? "INHERIT" :
133                   (inheritsched == PTHREAD_EXPLICIT_SCHED) ? "EXPLICIT" :
134                   "???");
135       }
136
137       int
138       main(int argc, char *argv[])
139       {
140           int s;
141           pthread_attr_t attr;
142
143           s = pthread_getattr_default_np(&attr);
144           if (s != 0)
145               errExitEN(s, "pthread_getattr_default_np");
146
147           display_pthread_attr(&attr);
148
149           exit(EXIT_SUCCESS);
150       }
151

SEE ALSO

153       pthread_attr_getaffinity_np(3), pthread_attr_getdetachstate(3),
154       pthread_attr_getguardsize(3), pthread_attr_getinheritsched(3),
155       pthread_attr_getschedparam(3), pthread_attr_getschedpolicy(3),
156       pthread_attr_getscope(3), pthread_attr_getstack(3),
157       pthread_attr_getstackaddr(3), pthread_attr_getstacksize(3),
158       pthread_attr_init(3), pthread_create(3), pthreads(7)
159

COLOPHON

161       This page is part of release 5.07 of the Linux man-pages project.  A
162       description of the project, information about reporting bugs, and the
163       latest version of this page, can be found at
164       https://www.kernel.org/doc/man-pages/.
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168Linux                             2020-06-09     PTHREAD_GETATTR_DEFAULT_NP(3)
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