pthread_getattr_default_np(3)

1pthread_getattr_default_np(3L)ibrary Functions Manuaplthread_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

LIBRARY

10       POSIX threads library (libpthread, -lpthread)
11

SYNOPSIS

13       #define _GNU_SOURCE             /* See feature_test_macros(7) */
14       #include <pthread.h>
15
16       int pthread_getattr_default_np(pthread_attr_t *attr);
17       int pthread_setattr_default_np(const pthread_attr_t *attr);
18

DESCRIPTION

20       The pthread_setattr_default_np() function sets the  default  attributes
21       used for creation of a new thread—that is, the attributes that are used
22       when pthread_create(3) is called with a second argument that  is  NULL.
23       The  default attributes are set using the attributes supplied in *attr,
24       a previously initialized thread attributes object.  Note the  following
25       details about the supplied attributes object:
26
27       •  The attribute settings in the object must be valid.
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29       •  The stack address attribute must not be set in the object.
30
31       •  Setting  the  stack  size  attribute to zero means leave the default
32          stack size unchanged.
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34       The pthread_getattr_default_np() function initializes  the  thread  at‐
35       tributes object referred to by attr so that it contains the default at‐
36       tributes used for thread creation.
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ERRORS

39       EINVAL (pthread_setattr_default_np()) One of the attribute settings  in
40              attr is invalid, or the stack address attribute is set in attr.
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42       ENOMEM (pthread_setattr_default_np()) Insufficient memory.
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ATTRIBUTES

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

STANDARDS

56       GNU; hence the suffix "_np" (nonportable) in their names.
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HISTORY

59       glibc 2.18.
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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 <err.h>
79       #include <errno.h>
80       #include <pthread.h>
81       #include <stdio.h>
82       #include <stdlib.h>
83
84       static void
85       display_pthread_attr(pthread_attr_t *attr)
86       {
87           int s;
88           size_t stacksize;
89           size_t guardsize;
90           int policy;
91           struct sched_param schedparam;
92           int detachstate;
93           int inheritsched;
94
95           s = pthread_attr_getstacksize(attr, &stacksize);
96           if (s != 0)
97               errc(EXIT_FAILURE, s, "pthread_attr_getstacksize");
98           printf("Stack size:          %zd\n", stacksize);
99
100           s = pthread_attr_getguardsize(attr, &guardsize);
101           if (s != 0)
102               errc(EXIT_FAILURE, s, "pthread_attr_getguardsize");
103           printf("Guard size:          %zd\n", guardsize);
104
105           s = pthread_attr_getschedpolicy(attr, &policy);
106           if (s != 0)
107               errc(EXIT_FAILURE, s, "pthread_attr_getschedpolicy");
108           printf("Scheduling policy:   %s\n",
109                  (policy == SCHED_FIFO) ? "SCHED_FIFO" :
110                  (policy == SCHED_RR) ? "SCHED_RR" :
111                  (policy == SCHED_OTHER) ? "SCHED_OTHER" : "[unknown]");
112
113           s = pthread_attr_getschedparam(attr, &schedparam);
114           if (s != 0)
115               errc(EXIT_FAILURE, s, "pthread_attr_getschedparam");
116           printf("Scheduling priority: %d\n", schedparam.sched_priority);
117
118           s = pthread_attr_getdetachstate(attr, &detachstate);
119           if (s != 0)
120               errc(EXIT_FAILURE, s, "pthread_attr_getdetachstate");
121           printf("Detach state:        %s\n",
122                  (detachstate == PTHREAD_CREATE_DETACHED) ? "DETACHED" :
123                  (detachstate == PTHREAD_CREATE_JOINABLE) ? "JOINABLE" :
124                  "???");
125
126           s = pthread_attr_getinheritsched(attr, &inheritsched);
127           if (s != 0)
128               errc(EXIT_FAILURE, s, "pthread_attr_getinheritsched");
129           printf("Inherit scheduler:   %s\n",
130                  (inheritsched == PTHREAD_INHERIT_SCHED) ? "INHERIT" :
131                  (inheritsched == PTHREAD_EXPLICIT_SCHED) ? "EXPLICIT" :
132                  "???");
133       }
134
135       int
136       main(void)
137       {
138           int s;
139           pthread_attr_t attr;
140
141           s = pthread_getattr_default_np(&attr);
142           if (s != 0)
143               errc(EXIT_FAILURE, s, "pthread_getattr_default_np");
144
145           display_pthread_attr(&attr);
146
147           exit(EXIT_SUCCESS);
148       }
149