set socket as inheritable

[PoncinMatthieu]

Setting the client socket as inheritable would fix issues with the debugger when the application creates a child process with os.execv. This behavior used to work prior to python 3.4, since python 3.4, sockets are by default not inheritable.
Link to the relevant python doc: https://docs.python.org/3/library/os.html#fd-inheritance

More specifically, this fix will allow us to debug bazel programs with the bazel intellij plugin. Thread here: bazelbuild/intellij#402

Edit: tests are failing but I'm not sure why, I'd be grateful if anyone could help with fixing those and merging the PR.

[fabioz]

Humm, something else seems off... by default when a new process is spawned, a new connection from the debugger to the client should be done instead of reusing a socket (so, I'm surprised making it inheritable actually works at all).

Do you know why that makes it work? Do you think it'd be possible to have a test-case which reproduces the issue (without Bazel in the middle?)

Note: the (few) failing tests are due to one unrelated issue (GitHub is having some issues on providing gdb which is needed for these tests).

[PoncinMatthieu]

ok I will try to reproduce it without Bazel in the middle and with the latest versions. If I manage to do so, I will look into writing a test case.

I've been using an older version of the debugger (as the latest version from main didn't work with the version of intellij compatible with the bazel plugin)

bazel: 3.7.0
intellij: 2020.1.4
intellij bazel plugin: 2020.10.19.0.3
pydevd: this branch is based on the tag 1.7.1, newer versions didn't work with intellij

so I wonder if it's possible the new connection behavior you described was added after 1.7.1 ?

I am not sure also if the debugger that is bundled with intellij is the exact same one on this repo, this was the procudure I used, let me know if that's complete non-sense:

cd ~/Library/Application\ Support/JetBrains/IntelliJIdea2020.1/plugins/python/helpers/
mv pydev pydev_save
git clone git@github.com:PoncinMatthieu/PyDev.Debugger.git pydev

[fabioz]

Humm, that seems a bit dangerous... I think Intellij has a fork which they update from time to time with this one. I don't know if they made any change on their own repo which they haven't upstreamed (which could potentially break their client implementation).

[PoncinMatthieu]

@fabioz I am indeed able to reproduce this.

Here is a minimal file to reproduce it with:

import sys, os

print("running main")
if len(sys.argv) == 1:
    os.execv(sys.executable, [sys.executable] + sys.argv + ["1"])

I will get this output with the patch:

running main
running main

Process finished with exit code 0

However without the patch I get always a keyboard interrupt:

running main
Failed to import the site module
Traceback (most recent call last):
  File "/Users/ponpon/.pyenv/versions/3.6.5/lib/python3.6/site.py", line 544, in <module>
    main()
  File "/Users/ponpon/.pyenv/versions/3.6.5/lib/python3.6/site.py", line 527, in main
    known_paths = venv(known_paths)
  File "/Users/ponpon/.pyenv/versions/3.6.5/lib/python3.6/site.py", line 464, in venv
    addsitepackages(known_paths, [sys.prefix])
  File "/Users/ponpon/.pyenv/versions/3.6.5/lib/python3.6/site.py", line 328, in addsitepackages
    addsitedir(sitedir, known_paths)
  File "/Users/ponpon/.pyenv/versions/3.6.5/lib/python3.6/site.py", line 207, in addsitedir
    addpackage(sitedir, name, known_paths)
  File "/Users/ponpon/.pyenv/versions/3.6.5/lib/python3.6/site.py", line 168, in addpackage
    exec(line)
  File "<string>", line 1, in <module>
KeyboardInterrupt

Process finished with exit code 1

The second process always receives a KeyboardInterrupt when the socket isn't set as inheritable.

I'm testing on OSX, the following showed the same results:

• latest Intellij (2020.3.2) + python 3.6.5 + intellij bundled pydevd
• latest Intellij (2020.3.2) + python 3.9.1 + intellij bundled pydevd
• latest Eclipse (2020-12) + python 3.9.1 + latest pydevd from http://www.pydev.org/updates (8.1.0.202012051215)
  Without patching the debugger and setting the socket as inheritable, I will get a single line running main.

However when I switch to python 3.3.7, it works as intended, printing 2 lines and confirming the regression from python 3.4.

[PoncinMatthieu]

I now tried to create a test case for it, but I am now stuck. The test fail as it is not breaking a second time on the same line during the second execution of the program. I'm not sure what I am missing, any pointers? Should the writer be reconnected somehow?