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(const 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  at‐
34       tributes object referred to by attr so that it contains the default at‐
35       tributes used for thread creation.
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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.
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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 at‐
48       tributes(7).
49
50       ┌────────────────────────────────────────────┬───────────────┬─────────┐
51Interface                                   Attribute     Value   
52       ├────────────────────────────────────────────┼───────────────┼─────────┤
53pthread_getattr_default_np(),               │ Thread safety │ MT-Safe │
54pthread_setattr_default_np()                │               │         │
55       └────────────────────────────────────────────┴───────────────┴─────────┘
56

CONFORMING TO

58       These  functions are nonstandard GNU extensions; hence the suffix "_np"
59       (nonportable) in their names.
60

EXAMPLES

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
67           $ ./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
75   Program source
76
77       #define _GNU_SOURCE
78       #include <pthread.h>
79       #include <stdio.h>
80       #include <stdlib.h>
81       #include <errno.h>
82
83       #define errExitEN(en, msg) \
84                               do { errno = en; perror(msg); \
85                                    exit(EXIT_FAILURE); } while (0)
86
87       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
98           s = pthread_attr_getstacksize(attr, &stacksize);
99           if (s != 0)
100               errExitEN(s, "pthread_attr_getstacksize");
101           printf("Stack size:          %zd\n", stacksize);
102
103           s = pthread_attr_getguardsize(attr, &guardsize);
104           if (s != 0)
105               errExitEN(s, "pthread_attr_getguardsize");
106           printf("Guard size:          %zd\n", guardsize);
107
108           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
116           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
121           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
129           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
138       int
139       main(int argc, char *argv[])
140       {
141           int s;
142           pthread_attr_t attr;
143
144           s = pthread_getattr_default_np(&attr);
145           if (s != 0)
146               errExitEN(s, "pthread_getattr_default_np");
147
148           display_pthread_attr(&attr);
149
150           exit(EXIT_SUCCESS);
151       }
152

SEE ALSO

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

COLOPHON

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/.
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169Linux                             2021-03-22     PTHREAD_GETATTR_DEFAULT_NP(3)
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