Making the exceptions pickleable

[randrej]

I'm often using httpx with multiprocessing queues and such, and whenever httpx throws I get an exception similar to this one. Adding proper __reduce__ methods to the exceptions, like explained here would mitigate this issue completely.

Here's a concrete example of the error occurring:

Traceback (most recent call last):
  File "/usr/local/lib/python3.9/concurrent/futures/process.py", line 384, in wait_result_broken_or_wakeup
    result_item = result_reader.recv()
  File "/usr/local/lib/python3.9/multiprocessing/connection.py", line 256, in recv
    return _ForkingPickler.loads(buf.getbuffer())
TypeError: __init__() missing 1 required keyword-only argument: 'request'

I'm offering to contribute this functionality if the maintainers are willing to merge it.

[achille-roussel]

Hello!

I'm chiming in to support a resolution of this issue, httpx is a popular package and we often end up with pickle errors when exceptions are serialized.

I'm happy to send a pull request to address if there is consensus.

[achille-roussel]

A pull request was opened to address the issue #3108

[camillol]

@tomchristie could you take another look at #3108? Looks like it addressed all comments.