1PTHREAD_SETNAME_NP(3) Linux Programmer's Manual PTHREAD_SETNAME_NP(3)
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6 pthread_setname_np, pthread_getname_np - set/get the name of a thread
7
9 #define _GNU_SOURCE /* See feature_test_macros(7) */
10 #include <pthread.h>
11 int pthread_setname_np(pthread_t thread, const char *name);
12 int pthread_getname_np(pthread_t thread,
13 char *name, size_t len);
14 Compile and link with -pthread.
16
18 By default, all the threads created using pthread_create() inherit the
19 program name. The pthread_setname_np() function can be used to set a
20 unique name for a thread, which can be useful for debugging multi‐
21 threaded applications. The thread name is a meaningful C language
22 string, whose length is restricted to 16 characters, including the ter‐
23 minating null byte ('\0'). The thread argument specifies the thread
24 whose name is to be changed; name specifies the new name.
25 The pthread_getname_np() function can be used to retrieve the name of
27 the thread. The thread argument specifies the thread whose name is to
28 be retrieved. The buffer name is used to return the thread name; len
29 specifies the number of bytes available in name. The buffer specified
30 by name should be at least 16 characters in length. The returned
31 thread name in the output buffer will be null terminated.
32
34 On success, these functions return 0; on error, they return a nonzero
35 error number.
36
38 The pthread_setname_np() function can fail with the following error:
39 ERANGE The length of the string specified pointed to by name exceeds
41 the allowed limit.
42 The pthread_getname_np() function can fail with the following error:
44 ERANGE The buffer specified by name and len is too small to hold the
46 thread name.
47 If either of these functions fails to open /proc/self/task/[tid]/comm,
49 then the call may fail with one of the errors described in open(2).
50
52 These functions first appeared in glibc in version 2.12.
53
55 For an explanation of the terms used in this section, see
56 attributes(7).
57 ┌──────────────────────┬───────────────┬─────────┐
59 │Interface │ Attribute │ Value │
60 ├──────────────────────┼───────────────┼─────────┤
61 │pthread_setname_np(), │ Thread safety │ MT-Safe │
62 │pthread_getname_np() │ │ │
63 └──────────────────────┴───────────────┴─────────┘
64
66 These functions are nonstandard GNU extensions; hence the suffix "_np"
67 (nonportable) in the names.
68
70 pthread_setname_np() internally writes to the thread-specific comm file
71 under the /proc filesystem: /proc/self/task/[tid]/comm. pthread_get‐
72 name_np() retrieves it from the same location.
73
75 The program below demonstrates the use of pthread_setname_np() and
76 pthread_getname_np().
77 The following shell session shows a sample run of the program:
79 $ ./a.out
81 Created a thread. Default name is: a.out
82 The thread name after setting it is THREADFOO.
83 ^Z # Suspend the program
84 [1]+ Stopped ./a.out
85 $ ps H -C a.out -o 'pid tid cmd comm'
86 PID TID CMD COMMAND
87 5990 5990 ./a.out a.out
88 5990 5991 ./a.out THREADFOO
89 $ cat /proc/5990/task/5990/comm
90 a.out
91 $ cat /proc/5990/task/5991/comm
92 THREADFOO
93 Program source
95 #define _GNU_SOURCE
97 #include <pthread.h>
98 #include <stdio.h>
99 #include <string.h>
100 #include <unistd.h>
101 #include <errno.h>
102 #include <stdlib.h>
103 #define NAMELEN 16
105 #define errExitEN(en, msg) \
107 do { errno = en; perror(msg); exit(EXIT_FAILURE); \
108 } while (0)
109 static void *
111 threadfunc(void *parm)
112 {
113 sleep(5); // allow main program to set the thread name
114 return NULL;
115 }
116 int
118 main(int argc, char **argv)
119 {
120 pthread_t thread;
121 int rc;
122 char thread_name[NAMELEN];
123 rc = pthread_create(&thread, NULL, threadfunc, NULL);
125 if (rc != 0)
126 errExitEN(rc, "pthread_create");
127 rc = pthread_getname_np(thread, thread_name, NAMELEN);
129 if (rc != 0)
130 errExitEN(rc, "pthread_getname_np");
131 printf("Created a thread. Default name is: %s\n", thread_name);
133 rc = pthread_setname_np(thread, (argc > 1) ? argv[1] : "THREADFOO");
134 if (rc != 0)
135 errExitEN(rc, "pthread_setname_np");
136 sleep(2);
138 rc = pthread_getname_np(thread, thread_name,
140 (argc > 2) ? atoi(argv[1]) : NAMELEN);
141 if (rc != 0)
142 errExitEN(rc, "pthread_getname_np");
143 printf("The thread name after setting it is %s.\n", thread_name);
144 rc = pthread_join(thread, NULL);
146 if (rc != 0)
147 errExitEN(rc, "pthread_join");
148 printf("Done\n");
150 exit(EXIT_SUCCESS);
151 }
152
154 prctl(2), pthread_create(3), pthreads(7)
155
157 This page is part of release 5.04 of the Linux man-pages project. A
158 description of the project, information about reporting bugs, and the
159 latest version of this page, can be found at
160 https://www.kernel.org/doc/man-pages/.
161Linux 2019-03-06 PTHREAD_SETNAME_NP(3)