Skip to content

gh-137400: Stop the world when swapping profile functions #137472

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

Closed
godlygeek wants to merge 2 commits into from
Closed

gh-137400: Stop the world when swapping profile functions #137472

Changes from 1 commit
Commits
Show all changes
2 commits
Select commit Hold shift + click to select a range
f29f878
gh-137400: Stop the world when swapping profile functions
godlygeek Aug 6, 2025
ba36824
Add news entry
godlygeek Aug 6, 2025
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
Next Next commit
gh-137400: Stop the world when swapping profile functions 
One thread's profile function or profile object can be changed from
another thread, for instance by `sys._setprofileallthreads`. This can
lead to crashes unless the two threads are synchronized. We need
a stop-the-world to ensure that the thread whose profile function or
profile object is being changed is in a state where it's not in the
middle of using either of those pointers.

Signed-off-by: Matt Wozniski <mwozniski@bloomberg.net>
  • Loading branch information
@godlygeek
godlygeek committed Aug 6, 2025
commit f29f87872941ac061ef64034373730683e0203fb
8 changes: 7 additions & 1 deletion Python/legacy_tracing.c
View file
Open in desktop
Original file line number Diff line number Diff line change
Expand Up @@ -484,13 +484,19 @@ setup_profile(PyThreadState *tstate, Py_tracefunc func, PyObject *arg, PyObject
}
}

_PyEval_StopTheWorld(tstate->interp);

int delta = (func != NULL) - (tstate->c_profilefunc != NULL);
tstate->c_profilefunc = func;
*old_profileobj = tstate->c_profileobj;
tstate->c_profileobj = Py_XNewRef(arg);
tstate->interp->sys_profiling_threads += delta;
assert(tstate->interp->sys_profiling_threads >= 0);
return tstate->interp->sys_profiling_threads;
Py_ssize_t ret = tstate->interp->sys_profiling_threads;

_PyEval_StartTheWorld(tstate->interp);

return ret;
}

int
Expand Down
Loading