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26 .TH PTHREAD_SETNAME_NP 3 2013-04-02 "Linux" "Linux Programmer's Manual"
28 pthread_setname_np, pthread_getname_np \- set/get the name of a thread
31 .BR "#define _GNU_SOURCE" " /* See feature_test_macros(7) */"
32 .B #include <pthread.h>
33 .BI "int pthread_setname_np(pthread_t " thread ", const char *" name ");
34 .BI "int pthread_getname_np(pthread_t " thread ,
35 .BI " const char *" name ", size_t " len );
38 Compile and link with \fI\-pthread\fP.
40 By default, all the threads created using
42 inherit the program name.
44 .BR pthread_setname_np ()
45 function can be used to set a unique name for a thread,
46 which can be useful for debugging
47 multithreaded applications.
48 The thread name is a meaningful C language string, whose length is
49 restricted to 16 characters, including the terminating null byte.
52 argument specifies the thread whose name is to be changed;
54 specifies the new name.
57 .BR pthread_getname_np ()
58 function can be used to retrieve the name of the thread.
61 argument specifies the thread whose name is to be retrieved.
64 is used to return the thread name;
66 specifies the number of bytes available in
68 The buffer specified by
70 should be at least 16 characters in length.
71 The returned thread name in the output buffer will be null terminated.
73 On success, these functions return 0;
74 on error, they return a nonzero error number.
77 .BR pthread_setname_np ()
78 function can fail with the following error:
81 The length of the string specified pointed to by
83 exceeds the allowed limit.
86 .BR pthread_getname_np ()
87 function can fail with the following error:
90 The buffer specified by
94 is too small to hold the thread name.
96 If either of these functions fails to open
97 .IR /proc/self/task/[tid]/comm ,
98 then the call may fail with one of the errors described in
101 These functions first appeared in glibc in version 2.12.
103 These functions are nonstandard GNU extensions.
105 .BR pthread_setname_np ()
106 internally writes to the thread specific comm file under
109 .IR /proc/self/task/[tid]/comm .
110 .BR pthread_getname_np ()
111 retrieves it from the same location.
114 The program below demonstrates the use of
115 .BR pthread_setname_np ()
117 .BR pthread_getname_np ().
119 The following shell session shows a sample run of the program:
124 Created a thread. Default name is: a.out
125 The thread name after setting it is THREADFOO.
126 \fB^Z\fP # Suspend the program
128 .RB "$ " "ps H -C a.out -o 'pid tid cmd comm'"
130 5990 5990 ./a.out a.out
131 5990 5991 ./a.out THREADFOO
132 .RB "$ " "cat /proc/5990/task/5990/comm"
134 .RB "$ " "cat /proc/5990/task/5991/comm"
151 #define errExitEN(en, msg) \\
152 do { errno = en; perror(msg); exit(EXIT_FAILURE); \\
156 threadfunc(void *parm)
158 sleep(5); // allow main program to set the thread name
163 main(int argc, char **argv)
167 char thread_name[NAMELEN];
169 rc = pthread_create(&thread, NULL, threadfunc, NULL);
171 errExitEN(rc, "pthread_create");
173 rc = pthread_getname_np(thread, thread_name, NAMELEN);
175 errExitEN(rc, "pthread_getname_np");
177 printf("Created a thread. Default name is: %s\\n", thread_name);
178 rc = pthread_setname_np(thread, (argc > 1) ? argv[1] : "THREADFOO");
180 errExitEN(rc, "pthread_setname_np");
184 rc = pthread_getname_np(thread, thread_name,
185 (argc > 2) ? atoi(argv[1]) : NAMELEN);
187 errExitEN(rc, "pthread_getname_np");
188 printf("The thread name after setting it is %s.\\n", thread_name);
190 rc = pthread_join(thread, NULL);
192 errExitEN(rc, "pthread_join");
202 .BR pthread_create (3),