How to set the name of a thread in Linux pthreads?

Question

Is there any way of setting the name of a thread in Linux?

My main purpose is it would be helpful while debugging, and also nice if that name was exposed through e.g

Answer 1

As of glibc v2.12, you can use pthread_setname_np and pthread_getname_np to set/get the thread name.

These interfaces are available on a few other POSIX systems (BSD, QNX, Mac) in various slightly different forms.

Setting the name will be something like this:

#include   // or maybe  for some OSes

// Linux
int pthread_setname_np(pthread_t thread, const char *name);

// NetBSD: name + arg work like printf(name, arg)
int pthread_setname_np(pthread_t thread, const char *name, void *arg);

// FreeBSD & OpenBSD: function name is slightly different, and has no return value
void pthread_set_name_np(pthread_t tid, const char *name);

// Mac OS X: must be set from within the thread (can't specify thread ID)
int pthread_setname_np(const char*);

And you can get the name back:

#include   // or  ?

// Linux, NetBSD:
int pthread_getname_np(pthread_t th, char *buf, size_t len);
// some implementations don't have a safe buffer (see MKS/IBM below)
int pthread_getname_np(pthread_t thread, const char **name);
int pthread_getname_np(pthread_t thread, char *name);

// FreeBSD & OpenBSD: dont' seem to have getname/get_name equivalent?
// but I'd imagine there's some other mechanism to read it directly for say gdb

// Mac OS X:
int pthread_getname_np(pthread_t, char*, size_t);

As you can see it's not completely portable between POSIX systems, but as far as I can tell across linux it should be consistent. Apart from Mac OS X (where you can only do it from within the thread), the others are at least simple to adapt for cross-platform code.

Sources:

• glibc NEWS (mentions new interfaces in 2.12)
• glibc nptl/ChangeLog (mentions new interfaces in 2.12)
• MKS setname / getname
• IBM setname / getname
• Mac OS X from /Developer/SDKs/MacOSX10.7.sdk/usr/include/pthread.h
• QNX setname / getname
• FreeBSD setname / no getname as far as i can see
• OpenBSD setname / no getname as far as i can see
• NetBSD setname / getname