Debugger times out at "Collecting data..."

I had the same question when i use pycharm2018.2 to debug my web application.

The project is a complex flask web server that combined with SocketIO.

When I made a debug breakpoint inside the code then pressed the debug button, it stopped at the breakpoint, but the variables didn't load. It just collected data data. I made some tweaks to the debugger settings in the end and this made it work. See the following image for the setting to change:

In case you landed here because you are using PyTorch (or any other deep learning library) and try to debug in PyCharm (torch 1.31, PyCharm 2019.2 in my case) but it's super slow:

Enable Gevent compatible in the Python Debugger settings as linkliu mayuyu pointed out. The problem might be caused due to debugging large deep learning models (BERT transformer in my case), but I'm not entirely sure about this.

I'm adding this answer as it's end of 2019 and this doesn't seem to be fixed yet. Further I think this is affecting many engineers using deep learning, so I hope my answer-formatting triggers their stackoverflow algorithm :-)

Note (June 2020):While adding the Gevent compatible allows you to debug PyTorch models, it will prevent you from debug your Flask application in PyCharm! My breakpoints were not working anymore and it took me a while to figure out that this flag is the reason for it. So make sure to enable it only on a per-project base.

I also had this issue when I was working on code using sympy and the Python module 'Lea' aiming to calculate probability distributions.

The action I took that resolved the timeout issue was to change the 'Variables Loading Policy' in the debug setting from the default 'Asynchronously' to 'Synchronously'.