Input() never returns when InteractiveShellEmbed is used?

[gigaj0ule]

I'm pretty stuck on this one here...

When I use an instance of InteractiveShellEmbed, if Input() is called from another thread, the program will freeze. Not even CTRL-C can break it!

It seems to be the case that Stdin is somehow bound by the interactiveshell, and so input() never receives any data. Further, attempts to directly get data from Stdin with a readline call fail also. Sometimes, I am able to get characters, but never a newline character.

Is there a way to either,

• Call input() in the interactiveshell programatically? (sadly, run_cell on the instance, will also hang...)
• Detach Stdin temporarily from interactiveshell?
• Bind a service that captures a copy of Stdin and forwards it to something else?
• Use some secret input method I am not aware of :-)

I am willing to put in the work to fix this if someone can point me in the right direction!

[Carreau]

Thanks for the report; that might be due to prompt toolkit hijacking input; there is likely a context manager to get a stdin that works. I know there is with patch_stdout (for stdout) but I would have to figure out for stdin.

[reszelaz]

Hi,
I'm not sure but I think I hit the same problem, I could reproduce it using this simple script: ipython_input.py.txt, in the following way:

╰─>$ ipython                                                                                                                                                                                                                                                         (ipython) 
Python 3.9.4 | packaged by conda-forge | (default, May 10 2021, 22:13:33) 
Type 'copyright', 'credits' or 'license' for more information
IPython 7.24.1 -- An enhanced Interactive Python. Type '?' for help.

In [1]: load workspace/ipython_input.py

In [2]: # %load workspace/ipython_input.py
   ...: import threading
   ...: import time
   ...: 
   ...: 
   ...: def foo():
   ...:     print("foo() entering")
   ...:     input("Type sth:")
   ...:     print("foo() exiting")
   ...: 
   ...: 
   ...: def bar():
   ...:     print("bar() entering")
   ...:     th = threading.Thread(target=foo)
   ...:     th.start()
   ...:     time.sleep(3)
   ...:     print("thread is alive: %s" % th.is_alive())
   ...:     print("bar() exiting")
   ...:     return th
   ...: 
   ...: th = bar()
   ...: print("thread is alive: %s" % th.is_alive())
   ...: 
bar() entering
foo() entering
Type sth:thread is alive: True
bar() exiting
thread is alive: True

In [3]:

After executing it, IPython hangs.
When I run the same script in a Python console, it works well.