Pytorch profiler not exporting any stack information?

I’m trying to export some stack information to generate flamegraphs by following this tutorial:

However, I can’t seem to get it work. Specifically, the generated file is always empty.

Here’s a snippet to reproduce:

#! /usr/bin/env python3
import torch
import torchvision.models as models
from torch.profiler import profile, record_function, ProfilerActivity

model = models.resnet18().cuda()
inputs = torch.randn(5, 3, 224, 224).cuda()

with profile(activities=[ProfilerActivity.CUDA], with_stack=True) as prof:

prof.export_stacks("stacks.txt", metric="self_cuda_time_total")

stacks.txt is always empty. Does anyone have suggestions on what I should do?