PTHREAD_SETNAME_NP(3) Linux Programmer's Manual PTHREAD_SETNAME_NP(3)
NAME
pthread_setname_np, pthread_getname_np - set/get the name of a thread
SYNOPSIS
#define _GNU_SOURCE /* See feature_test_macros(7) */
#include <pthread.h>
int pthread_setname_np(pthread_t thread, const char *name);
int pthread_getname_np(pthread_t thread,
char *name, size_t len);
Compile and link with -pthread.
DESCRIPTION
By default, all the threads created using pthread_create() inherit the
program name. The pthread_setname_np() function can be used to set a
unique name for a thread, which can be useful for debugging multi-
threaded applications. The thread name is a meaningful C language
string, whose length is restricted to 16 characters, including the ter-
minating null byte ('\0'). The thread argument specifies the thread
whose name is to be changed; name specifies the new name.
The pthread_getname_np() function can be used to retrieve the name of
the thread. The thread argument specifies the thread whose name is to
be retrieved. The buffer name is used to return the thread name; len
specifies the number of bytes available in name. The buffer specified
by name should be at least 16 characters in length. The returned
thread name in the output buffer will be null terminated.
RETURN VALUE
On success, these functions return 0; on error, they return a nonzero
error number.
ERRORS
The pthread_setname_np() function can fail with the following error:
ERANGE The length of the string specified pointed to by name exceeds
the allowed limit.
The pthread_getname_np() function can fail with the following error:
ERANGE The buffer specified by name and len is too small to hold the
thread name.
If either of these functions fails to open /proc/self/task/[tid]/comm,
then the call may fail with one of the errors described in open(2).
VERSIONS
These functions first appeared in glibc in version 2.12.
ATTRIBUTES
For an explanation of the terms used in this section, see at-
tributes(7).
+----------------------+---------------+---------+
|Interface | Attribute | Value |
+----------------------+---------------+---------+
|pthread_setname_np(), | Thread safety | MT-Safe |
|pthread_getname_np() | | |
+----------------------+---------------+---------+
CONFORMING TO
These functions are nonstandard GNU extensions; hence the suffix "_np"
(nonportable) in the names.
NOTES
pthread_setname_np() internally writes to the thread-specific comm file
under the /proc filesystem: /proc/self/task/[tid]/comm. pthread_get-
name_np() retrieves it from the same location.
EXAMPLES
The program below demonstrates the use of pthread_setname_np() and
pthread_getname_np().
The following shell session shows a sample run of the program:
$ ./a.out
Created a thread. Default name is: a.out
The thread name after setting it is THREADFOO.
^Z # Suspend the program
[1]+ Stopped ./a.out
$ ps H -C a.out -o 'pid tid cmd comm'
PID TID CMD COMMAND
5990 5990 ./a.out a.out
5990 5991 ./a.out THREADFOO
$ cat /proc/5990/task/5990/comm
a.out
$ cat /proc/5990/task/5991/comm
THREADFOO
Program source
#define _GNU_SOURCE
#include <pthread.h>
#include <stdio.h>
#include <string.h>
#include <unistd.h>
#include <errno.h>
#include <stdlib.h>
#define NAMELEN 16
#define errExitEN(en, msg) \
do { errno = en; perror(msg); exit(EXIT_FAILURE); \
} while (0)
static void *
threadfunc(void *parm)
{
sleep(5); // allow main program to set the thread name
return NULL;
}
int
main(int argc, char **argv)
{
pthread_t thread;
int rc;
char thread_name[NAMELEN];
rc = pthread_create(&thread, NULL, threadfunc, NULL);
if (rc != 0)
errExitEN(rc, "pthread_create");
rc = pthread_getname_np(thread, thread_name, NAMELEN);
if (rc != 0)
errExitEN(rc, "pthread_getname_np");
printf("Created a thread. Default name is: %s\n", thread_name);
rc = pthread_setname_np(thread, (argc > 1) ? argv[1] : "THREADFOO");
if (rc != 0)
errExitEN(rc, "pthread_setname_np");
sleep(2);
rc = pthread_getname_np(thread, thread_name,
(argc > 2) ? atoi(argv[1]) : NAMELEN);
if (rc != 0)
errExitEN(rc, "pthread_getname_np");
printf("The thread name after setting it is %s.\n", thread_name);
rc = pthread_join(thread, NULL);
if (rc != 0)
errExitEN(rc, "pthread_join");
printf("Done\n");
exit(EXIT_SUCCESS);
}
SEE ALSO
prctl(2), pthread_create(3), pthreads(7)
COLOPHON
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description of the project, information about reporting bugs, and the
latest version of this page, can be found at
https://www.kernel.org/doc/man-pages/.
Linux 2020-06-09 PTHREAD_SETNAME_NP(3)