Hi Victor
Thanks for your reply. Indeed, upon further investigation, I have realised
changing the value of thread_id is not wise as there are other methods that
expect this field to be a pthread_t. I have opened issue
https://bugs.python.org/issue43879https://bugs.python.org/issue43879 to
have the new field added. I'm happy to do the work myself if it gets
accepted.
Cheers,
Gabriele
On Sat, 17 Apr 2021, 11:07 Victor Stinner, <vstin...@python.org> wrote:
> Hi,
>
> There are two reasons:
>
> * PyThread_get_thread_native_id() was only added recently (Python 3.8)
> * PyThread_get_thread_native_id() is not portable and not available on
> all platforms: the function is only declared if the
> PY_HAVE_THREAD_NATIVE_ID macro is defined.
>
> Maybe PyThreadState.thread_id could use
> PyThread_get_thread_native_id() if avaialble, or
> PyThread_get_thread_ident() otherwise. But that sounds like an
> incompatible change.
>
> Another approach would be to add a *new* structure member, like
> thread_native_id. It would not exist if the PY_HAVE_THREAD_NATIVE_ID
> macro is not defined.
>
>
> Include/pythread.h:
>
> #if defined(__APPLE__) || defined(__linux__) || defined(__FreeBSD__)
> || defined(__OpenBSD__) || defined(__NetBSD__) || defined(_WIN32) ||
> defined(_AIX)
> #define PY_HAVE_THREAD_NATIVE_ID
> PyAPI_FUNC(unsigned long) PyThread_get_thread_native_id(void);
> #endif
>
>
> thread_pthread.h implementation:
>
> unsigned long
> PyThread_get_thread_native_id(void)
> {
> if (!initialized)
> PyThread_init_thread();
> #ifdef __APPLE__
> uint64_t native_id;
> (void) pthread_threadid_np(NULL, &native_id);
> #elif defined(__linux__)
> pid_t native_id;
> native_id = syscall(SYS_gettid);
> #elif defined(__FreeBSD__)
> int native_id;
> native_id = pthread_getthreadid_np();
> #elif defined(__OpenBSD__)
> pid_t native_id;
> native_id = getthrid();
> #elif defined(_AIX)
> tid_t native_id;
> native_id = thread_self();
> #elif defined(__NetBSD__)
> lwpid_t native_id;
> native_id = _lwp_self();
> #endif
> return (unsigned long) native_id;
> }
>
> Victor
> --
> Night gathers, and now my watch begins. It shall not end until my death.
>
>
> On Fri, Apr 16, 2021 at 10:47 PM Gabriele <phoenix1...@gmail.com> wrote:
> >
> > Hi all.
> >
> > My apologies if this is a topic that's been discussed already, but I
> > wasn't able to locate anything in the archive on the subject. I was
> > wondering if there's a fundamental reason for using
> > PyThread_get_thread_ident instead of PyThread_get_thread_native_id for
> > the value of the thread_id field of the PyThreadState object.
> >
> > The reason why I'm asking is that I would like to have easy access to
> > the native TID on Linux to identify the /proc/stat file associated
> > with the thread from an external process. At the moment I have to
> > resort to calling process_vm_readv to copy the struct pthread over to
> > local VM and then guess where the tid field might be. So, if there's
> > no fundamental reason for thread_id to be PyThread_get_thread_ident, I
> > would like to propose to change it to PyThread_get_thread_native_id
> > instead.
> >
> > Thanks,
> > Gabriele
> >
> > --
> > "Egli è scritto in lingua matematica, e i caratteri son triangoli,
> > cerchi, ed altre figure
> > geometriche, senza i quali mezzi è impossibile a intenderne umanamente
> parola;
> > senza questi è un aggirarsi vanamente per un oscuro laberinto."
> >
> > -- G. Galilei, Il saggiatore.
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