Issue 33067: http.client no longer sends HTTP request in one TCP package

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This issue has been migrated to GitHub: https://github.com/python/cpython/issues/77248

classification

Title:	http.client no longer sends HTTP request in one TCP package
Type:	behavior	Stage:
Components:	Library (Lib)	Versions:	Python 3.8, Python 3.7, Python 3.6

process

Status:	open	Resolution:
Dependencies:		Superseder:
Assigned To:		Nosy List:	benjamin.peterson, christian.heimes, orsenthil
Priority:	normal	Keywords:	3.5regression

Created on 2018-03-13 12:06 by christian.heimes, last changed 2022-04-11 14:58 by admin.

Messages (1)
msg313743 - (view)	Author: Christian Heimes (christian.heimes) *	Date: 2018-03-13 12:06
https://bugs.python.org/issue23302 changed how http.client sends request. endheaders() no longer sends header and message body in one TCP package if the total payload is smaller than TCP max segment size. https://github.com/python/cpython/blob/3.5/Lib/http/client.py#L934-L936 uses two send calls to send header and body. This causes very simple HTTP servers in embedded devices to fail. Matthew Garrett noticed the bug, see https://twitter.com/mjg59/status/972985566387032064 / https://twitter.com/mjg59/status/973000950439817217 We should try to send requests as one TCP package again. TCP_CORK may do the trick. Or we should fix our custom implementation of send. It has multiple issues, e.g. a fixed buffer. The buffer size is suboptimal for small MTU and jumbo frames.

msg313743 - (view)

Author: Christian Heimes (christian.heimes) * (Python committer)

Date: 2018-03-13 12:06

https://bugs.python.org/issue23302 changed how http.client sends request. endheaders() no longer sends header and message body in one TCP package if the total payload is smaller than TCP max segment size. https://github.com/python/cpython/blob/3.5/Lib/http/client.py#L934-L936 uses two send calls to send header and body. This causes very simple HTTP servers in embedded devices to fail.

Matthew Garrett noticed the bug, see https://twitter.com/mjg59/status/972985566387032064 / https://twitter.com/mjg59/status/973000950439817217

We should try to send requests as one TCP package again. TCP_CORK may do the trick. Or we should fix our custom implementation of send. It has multiple issues, e.g. a fixed buffer. The buffer size is suboptimal for small MTU and jumbo frames.

History
Date	User	Action	Args
2022-04-11 14:58:58	admin	set	github: 77248
2018-03-13 17:40:23	orsenthil	set	nosy: + orsenthil
2018-03-13 12:06:43	christian.heimes	create