diff --git a/Misc/NEWS.d/next/Library/2026-06-13-04-11-00.gh-issue-151426.f2V67e.rst b/Misc/NEWS.d/next/Library/2026-06-13-04-11-00.gh-issue-151426.f2V67e.rst new file mode 100644 index 000000000000000..428302e5f847f36 --- /dev/null +++ b/Misc/NEWS.d/next/Library/2026-06-13-04-11-00.gh-issue-151426.f2V67e.rst @@ -0,0 +1,4 @@ +Fix impossible stack traces (callers and callees cross called, orphans and +incorrect lines) in the Tachyon profiler when caching frames, by snapshotting +the stack chunks before walking the frame chain on a cache miss. Patch by +Maurycy Pawłowski-Wieroński. diff --git a/Modules/_remote_debugging/frames.c b/Modules/_remote_debugging/frames.c index d73cd080dc477f3..e7d2a2764390261 100644 --- a/Modules/_remote_debugging/frames.c +++ b/Modules/_remote_debugging/frames.c @@ -580,6 +580,14 @@ collect_frames_with_cache( return full_hit < 0 ? -1 : 0; } + assert(ctx->chunks != NULL); + + if (ctx->chunks->count == 0) { + if (copy_stack_chunks(unwinder, ctx->thread_state_addr, ctx->chunks) < 0) { + PyErr_Clear(); + } + } + Py_ssize_t frames_before = PyList_GET_SIZE(ctx->frame_info); if (process_frame_chain(unwinder, ctx) < 0) {