Client connections always time out after 5 minutes by default, and this is not documented

[Lx]

• Python version: 3.10.4
• Operating System: macOS 12.4 (21F79)
• aiohttp version: 3.8.1

This is related to #2 but is not a duplicate as it concerns documentation, and the previous issue was closed before the circumstances of the timeout were fully understood.

Description

1. Regardless of keep-alive activity, the default usage of sse_client.EventSource as given in the README times out after 5 minutes:

   async with sse_client.EventSource(
       'https://stream.wikimedia.org/v2/stream/recentchange'
   ) as event_source:
       ...

2. There is no documentation in the README to state that this will occur.

Resolution

Ideally one of two things would resolve this issue:

1. Remove the default timeout, which is what aiosseclient does.

2. If there is sufficient* justification to keep the timeout, then document the justification and the workaround in the README:

   Timeouts

   Note that aiohttp requests have a default timeout of 5 minutes, inclusive of all traffic—that is, all aiohttp-sse-client requests will unconditionally time out after 5 minutes regardless of activity. This default has been retained in aiohttp-sse-client because ...

   To prevent this behaviour, disable the timeout by passing a timeout argument to the underlying request call:

   async with sse_client.EventSource(
       'https://stream.wikimedia.org/v2/stream/recentchange',
       timeout=None,
   ) as event_source:
       ...

   • It's important to note that this default timeout fires unconditionally, even if keep-alive activity occurs, and exists in aiohttp because it is a sensible default for normal traffic (not long-running SSE traffic).

[Lx]

A third option, which would probably be the best of both worlds, is to set a default aiohttp.ClientTimeout instance that has no total timeout but still provides a reasonable default timeout value for sock_connect only.

This option satisfies the maintainer's desire to keep a default timeout, but makes the timeout sensible for SSE traffic.