This is an issue in relation to python and the interpetter shell. If
the python shell is running something and it is not done then when the
user goes back the the document that was being editted emacs will
freeze. If the user hits C-g then a keyboard interupt is sent to the
interpeter and the action that was being run is canceled. If the user
has the misfortune of using the mouse to click into another window then
emacs will not be able to be recovered (haven't tested that last part
entirely but the easiest way is to get back to working is to 'sudo
killall emacs')
The issue seems to be with eldoc mode. If eldoc mode (or
global-eldoc-mode) is on then python.el tries to send something to the
interepter to get the definition of the symbol at the point and then
since something is running in the interpetter emacs will hang while
waiting for the interpetter to repond. This issue is most obvious in
emacs 25 because global-eldoc-mode is on by default. This causes loss of
data.
This bug is easily reproducable from emacs -Q.
- run emacs -Q
- Open a file /tmp/test.py (or any other python file)
- C-c C-p to start the interpetter (it does not matter if the interpetter
is dedicated or not)
- in the interpetter write an expression that will not terminate
e.g. while True: 2+2
e.g. (anything that plots in matplotlib)
- go back to /tmp/test.py and type anything.
- you will now be frozen
- type C-g to send a keyboard interupt to the interpetter
repeating these steps without global-eldoc-mode does not cause any
issues
The most obvious fix that I have found and use is to set
global-eldoc-mode to -1 on init.