man-pages/man3/pthread_setname_np.3

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.\" Copyright (C) 2012 Chandan Apsangi <chandan.jc@gmail.com>
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.TH PTHREAD_SETNAME_NP 3 2013-02-04 "Linux" "Linux Programmer's Manual"
.SH NAME
pthread_setname_np, pthread_getname_np \- set/get the name of a thread
.SH SYNOPSIS
.nf
.BR "#define _GNU_SOURCE" " /* See feature_test_macros(7) */"
.B #include <pthread.h>
.BI "int pthread_setname_np(pthread_t *" thread ", const char *" name ");
.BI "int pthread_getname_np(pthread_t *" thread ,
.BI " const char *" name ", size_t " len );
.fi
.sp
Compile and link with \fI\-pthread\fP.
.SH DESCRIPTION
By default, all the threads created using
.BR pthread_create ()
inherit the program name.
The
.BR pthread_setname_np ()
fuction 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 terminating null byte.
The
.BR pthread_getname_np ()
function can be used to retrieve the name of the thread.
The buffer specified by
.I name
must be at least 16 characters in length.
The returned thread name in the output buffer will be null terminated.
.SH RETURN VALUE
On success, these functions return 0;
on error, they return a nonzero error number.
.SH ERRORS
.TP
.B ERANGE
.RB ( pthread_setname_np ())
The length of the string specified pointed to by
.I name
exceeds the allowed limit.
.PP
If either of these functions fails to open
.IR /proc/self/task/[tid]/comm ,
then the call may fail with one of the errors described in
.BR open (2).
.SH NOTES
.BR pthread_setname_np ()
internally writes to the thread specific comm file under
.IR /proc
filesystem:
.IR /proc/self/task/[tid]/comm .
.BR pthread_getname_np ()
retreives it from the same location.
.SH EXAMPLE
.PP
The program below demonstrates the use of
.BR pthread_setname_np ()
and
.BR pthread_getname_np ().
The following shell session shows a sample run of the program:
.in +4n
.nf
.RB "$" " ./a.out"
Created a thread. Default name is: a.out
The thread name after setting it is THREADFOO.
Done
.fi
.in
.SS Program source
\&
.nf
#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, 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);
}
.fi
.SH SEE ALSO
.ad l
.nh
.BR prctl (2),
.BR pthread_create (3),
.BR pthreads (7)