`_remote_debugging`: dead code, unnecessary gc state read

[maurycy]

Bug report

Bug description:

I'm benchmarking sampling.profiler and I realized unwind_stack_for_thread issues _Py_RemoteDebug_PagedReadRemoteMemory on every sample and on every thread.

cpython/Modules/_remote_debugging/threads.c

Lines 317 to 328 in 665b7df

	// Read GC collecting state from the interpreter (before any skip checks)
	uintptr_t interp_addr = GET_MEMBER(uintptr_t, ts, unwinder->debug_offsets.thread_state.interp);
	// Read the GC runtime state from the interpreter state
	uintptr_t gc_addr = interp_addr + unwinder->debug_offsets.interpreter_state.gc;
	char gc_state[SIZEOF_GC_RUNTIME_STATE];
	if (_Py_RemoteDebug_PagedReadRemoteMemory(&unwinder->handle, gc_addr, unwinder->debug_offsets.gc.size, gc_state) < 0) {
	set_exception_cause(unwinder, PyExc_RuntimeError, "Failed to read GC state");
	goto error;
	}
	STATS_INC(unwinder, memory_reads);
	STATS_ADD(unwinder, memory_bytes_read, unwinder->debug_offsets.gc.size);

seems it should've been removed with 274a26c.

The result is not used, it pollutes the stats and there's a risk of failing over data that's not even used?

CPython versions tested on:

CPython main branch

Operating systems tested on:

macOS

Linked PRs

• gh-148989: _remote_debugging: Remove dead code, unnecessary gc state read #148990

[maurycy]

Fixed by #148990, done.