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26 .TH PTHREAD_SETNAME_NP 3 2019-03-06 "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 " 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 (\(aq\e0\(aq).
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 For an explanation of the terms used in this section, see
109 Interface Attribute Value
111 .BR pthread_setname_np (),
112 .BR pthread_getname_np ()
113 T} Thread safety MT-Safe
117 These functions are nonstandard GNU extensions;
118 hence the suffix "_np" (nonportable) in the names.
120 .BR pthread_setname_np ()
121 internally writes to the thread-specific
126 .IR /proc/self/task/[tid]/comm .
127 .BR pthread_getname_np ()
128 retrieves it from the same location.
131 The program below demonstrates the use of
132 .BR pthread_setname_np ()
134 .BR pthread_getname_np ().
136 The following shell session shows a sample run of the program:
141 Created a thread. Default name is: a.out
142 The thread name after setting it is THREADFOO.
143 \fB^Z\fP # Suspend the program
145 .RB "$ " "ps H -C a.out -o 'pid tid cmd comm'"
147 5990 5990 ./a.out a.out
148 5990 5991 ./a.out THREADFOO
149 .RB "$ " "cat /proc/5990/task/5990/comm"
151 .RB "$ " "cat /proc/5990/task/5991/comm"
168 #define errExitEN(en, msg) \e
169 do { errno = en; perror(msg); exit(EXIT_FAILURE); \e
173 threadfunc(void *parm)
175 sleep(5); // allow main program to set the thread name
180 main(int argc, char **argv)
184 char thread_name[NAMELEN];
186 rc = pthread_create(&thread, NULL, threadfunc, NULL);
188 errExitEN(rc, "pthread_create");
190 rc = pthread_getname_np(thread, thread_name, NAMELEN);
192 errExitEN(rc, "pthread_getname_np");
194 printf("Created a thread. Default name is: %s\en", thread_name);
195 rc = pthread_setname_np(thread, (argc > 1) ? argv[1] : "THREADFOO");
197 errExitEN(rc, "pthread_setname_np");
201 rc = pthread_getname_np(thread, thread_name,
202 (argc > 2) ? atoi(argv[1]) : NAMELEN);
204 errExitEN(rc, "pthread_getname_np");
205 printf("The thread name after setting it is %s.\en", thread_name);
207 rc = pthread_join(thread, NULL);
209 errExitEN(rc, "pthread_join");
219 .BR pthread_create (3),