.\" Copyright (C) 2012 Chandan Apsangi <chandan.jc@gmail.com>
+.\" and Copyright (C) 2013 Michael Kerrisk <mtk.manpages@gmail.com>
.\"
+.\" %%%LICENSE_START(VERBATIM)
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.\" manual provided the copyright notice and this permission notice are
.\" preserved on all copies.
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-.TH PTHREAD_SETNAME_NP 3 2013-02-04 "Linux" "Linux Programmer's Manual"
+.TH PTHREAD_SETNAME_NP 3 2019-03-06 "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 );
+.BI "int pthread_setname_np(pthread_t " thread ", const char *" name ");
+.BI "int pthread_getname_np(pthread_t " thread ,
+.BI " char *" name ", size_t " len );
.fi
-.sp
+.PP
Compile and link with \fI\-pthread\fP.
.SH DESCRIPTION
By default, all the threads created using
inherit the program name.
The
.BR pthread_setname_np ()
-fuction can be used to set a unique name for a thread,
+function can be used to set a unique name for a thread,
which can be useful for debugging
-multi-threaded applications.
+multithreaded applications.
The thread name is a meaningful C language string, whose length is
-restricted to 16 characters, including the terminating null byte.
-
+restricted to 16 characters, including the terminating null byte (\(aq\e0\(aq).
+The
+.I thread
+argument specifies the thread whose name is to be changed;
+.I name
+specifies the new name.
+.PP
The
.BR pthread_getname_np ()
function can be used to retrieve the name of the thread.
+The
+.I thread
+argument specifies the thread whose name is to be retrieved.
+The buffer
+.I name
+is used to return the thread name;
+.I len
+specifies the number of bytes available in
+.IR name .
The buffer specified by
.I name
-must be at least 16 characters in length.
+should 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
+The
+.BR pthread_setname_np ()
+function can fail with the following error:
.TP
.B ERANGE
-.RB ( pthread_setname_np ())
The length of the string specified pointed to by
.I name
exceeds the allowed limit.
.PP
+The
+.BR pthread_getname_np ()
+function can fail with the following error:
+.TP
+.B ERANGE
+The buffer specified by
+.I name
+and
+.I len
+is too small to hold the thread name.
+.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 VERSIONS
+These functions first appeared in glibc in version 2.12.
+.SH ATTRIBUTES
+For an explanation of the terms used in this section, see
+.BR attributes (7).
+.TS
+allbox;
+lbw21 lb lb
+l l l.
+Interface Attribute Value
+T{
+.BR pthread_setname_np (),
+.BR pthread_getname_np ()
+T} Thread safety MT-Safe
+.TE
+.sp 1
+.SH CONFORMING TO
+These functions are nonstandard GNU extensions;
+hence the suffix "_np" (nonportable) in the names.
.SH NOTES
.BR pthread_setname_np ()
-internally writes to the thread specific comm file under
+internally writes to the thread-specific
+.I comm
+file under the
.IR /proc
filesystem:
.IR /proc/self/task/[tid]/comm .
.BR pthread_getname_np ()
-retreives it from the same location.
-
-.SH EXAMPLE
+retrieves it from the same location.
+.SH EXAMPLES
.PP
The program below demonstrates the use of
.BR pthread_setname_np ()
and
.BR pthread_getname_np ().
-
+.PP
The following shell session shows a sample run of the program:
+.PP
.in +4n
-.nf
-
+.EX
.RB "$" " ./a.out"
Created a thread. Default name is: a.out
The thread name after setting it is THREADFOO.
-Done
-.fi
+\fB^Z\fP # Suspend the program
+[1]+ Stopped ./a.out
+.RB "$ " "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
+.RB "$ " "cat /proc/5990/task/5990/comm"
+a.out
+.RB "$ " "cat /proc/5990/task/5991/comm"
+THREADFOO
+.EE
.in
-
.SS Program source
\&
-.nf
+.EX
#define _GNU_SOURCE
#include <pthread.h>
#include <stdio.h>
#define NAMELEN 16
-#define errExitEN(en, msg) \\
- do { errno = en; perror(msg); exit(EXIT_FAILURE); \\
+#define errExitEN(en, msg) \e
+ do { errno = en; perror(msg); exit(EXIT_FAILURE); \e
} while (0)
-static void *threadfunc(void *parm)
+static void *
+threadfunc(void *parm)
{
sleep(5); // allow main program to set the thread name
return NULL;
}
-int main(int argc, char **argv)
+int
+main(int argc, char **argv)
{
pthread_t thread;
int rc;
if (rc != 0)
errExitEN(rc, "pthread_getname_np");
- printf("Created a thread. Default name is: %s\\n", thread_name);
+ printf("Created a thread. Default name is: %s\en", 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);
+
+ 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);
-
+ printf("The thread name after setting it is %s.\en", thread_name);
+
rc = pthread_join(thread, NULL);
if (rc != 0)
errExitEN(rc, "pthread_join");
-
- printf("Done\\n");
+
+ printf("Done\en");
exit(EXIT_SUCCESS);
}
-
-.fi
+.EE
.SH SEE ALSO
.ad l
.nh
projects / thirdparty / man-pages.git / blobdiff