Skip to content

gh-103323: Get the "Current" Thread State from a Thread-Local Variable #103324

New issue

Have a question about this project? Sign up for a free GitHub account to open an issue and contact its maintainers and the community.

Sign up for GitHub

By clicking “Sign up for GitHub”, you agree to our terms of service and privacy statement. We’ll occasionally send you account related emails.

Already on GitHub? Sign in to your account

Merged
ericsnowcurrently merged 12 commits into from
Apr 24, 2023
Merged

gh-103323: Get the "Current" Thread State from a Thread-Local Variable #103324

Show file tree
Hide file tree
Changes from 1 commit
Commits
Show all changes
12 commits
Select commit Hold shift + click to select a range
c4db85a
Add a thread_local macro.
ericsnowcurrently Jan 10, 2023
47a7094
tstate_current -> thread_local.
ericsnowcurrently Apr 6, 2023
cf22de1
Add _PyThraedState_GetCurrent().
ericsnowcurrently Apr 7, 2023
d4136d2
Add HAVE_THREAD_LOCAL.
ericsnowcurrently Apr 7, 2023
f8c6598
Support the faster approach, if available.
ericsnowcurrently Apr 7, 2023
9496df0
Do not fail if thread_local not supported.
ericsnowcurrently Apr 7, 2023
2c335a3
thread_local -> _Py_thread_local
ericsnowcurrently Apr 7, 2023
4af0ce7
Only define _Py_thread_local for the core runtime.
ericsnowcurrently Apr 7, 2023
3db4007
Fix pystate.c.
ericsnowcurrently Apr 7, 2023
d573053
Call _PyThreadState_GET() from _PyRuntimeState_GetThreadState().
ericsnowcurrently Apr 7, 2023
feb8ef5
Fix the error message.
ericsnowcurrently Apr 7, 2023
2332a2e
Add a NEWS entry.
ericsnowcurrently Apr 7, 2023
File filter

Filter by extension

Filter by extension
Conversations
Failed to load comments.
Loading
Jump to
Jump to file
Failed to load files.
Loading
Diff view
Diff view
Prev Previous commit
Next Next commit
Fix pystate.c.
  • Loading branch information
@ericsnowcurrently
ericsnowcurrently committed Apr 7, 2023
commit 3db400735ac2ce1a7814a2878fa3ec308e46dcfe
2 changes: 1 addition & 1 deletion Include/internal/pycore_pystate.h
View file
Open in desktop
Original file line number Diff line number Diff line change
Expand Up @@ -65,7 +65,7 @@ _Py_ThreadCanHandlePendingCalls(void)
and interpreter state */

#if defined(HAVE_THREAD_LOCAL) && !defined(Py_BUILD_CORE_MODULE)
extern thread_local PyThreadState *_Py_tss_tstate;
extern _Py_thread_local PyThreadState *_Py_tss_tstate;
#endif
PyAPI_DATA(PyThreadState *) _PyThreadState_GetCurrent(void);
Copy link
Copy Markdown
Member

@vstinner vstinner May 4, 2023

Choose a reason for hiding this comment

The reason will be displayed to describe this comment to others. Learn more.

What is the use case for this new _PyThreadState_GetCurrent() function? There is already PyThreadState_Get(). How is it different?

The API to get the current thread state is already complicated and has a complicated history: https://pythondev.readthedocs.io/pystate.html

Copy link
Copy Markdown
Member Author

@ericsnowcurrently ericsnowcurrently May 4, 2023

Choose a reason for hiding this comment

The reason will be displayed to describe this comment to others. Learn more.

It's there because I couldn't find a way to mix PyAPI_DATA with _Py_thread_local. Looks like that's the same issue you ran into in 2020.


Expand Down
31 changes: 24 additions & 7 deletions Python/pystate.c
View file
Open in desktop
Original file line number Diff line number Diff line change
Expand Up @@ -61,38 +61,55 @@ extern "C" {
*/


thread_local PyThreadState *_Py_tss_tstate = NULL;

PyThreadState *
_PyThreadState_GetCurrent(void)
{
return _Py_tss_tstate;
}
#ifdef HAVE_THREAD_LOCAL
_Py_thread_local PyThreadState *_Py_tss_tstate = NULL;
#endif

static inline PyThreadState *
current_fast_get(_PyRuntimeState *Py_UNUSED(runtime))
{
#ifdef HAVE_THREAD_LOCAL
return _Py_tss_tstate;
#else
// XXX Fall back to the PyThread_tss_*() API.
# error "no supported thread-local variable storage classifier"
#endif
}

static inline void
current_fast_set(_PyRuntimeState *Py_UNUSED(runtime), PyThreadState *tstate)
{
assert(tstate != NULL);
#ifdef HAVE_THREAD_LOCAL
_Py_tss_tstate = tstate;
#else
// XXX Fall back to the PyThread_tss_*() API.
# error "no supported thread-local variable storage classifier"
#endif
}

static inline void
current_fast_clear(_PyRuntimeState *Py_UNUSED(runtime))
{
#ifdef HAVE_THREAD_LOCAL
_Py_tss_tstate = NULL;
#else
// XXX Fall back to the PyThread_tss_*() API.
# error "no supported thread-local variable storage classifier"
#endif
}

#define tstate_verify_not_active(tstate) \
if (tstate == current_fast_get((tstate)->interp->runtime)) { \
_Py_FatalErrorFormat(__func__, "tstate %p is still current", tstate); \
}

PyThreadState *
_PyThreadState_GetCurrent(void)
{
return current_fast_get(&_PyRuntime);
}


//------------------------------------------------
// the thread state bound to the current OS thread
Expand Down