PyOS_Readline uses single lock

[albertz]

BPO	12861
Nosy	@amauryfa, @vstinner, @albertz

^{Note: these values reflect the state of the issue at the time it was migrated and might not reflect the current state.}

Show more details

GitHub fields:

assignee = None
closed_at = <Date 2020-06-25.09:46:44.184>
created_at = <Date 2011-08-30.17:15:54.957>
labels = []
title = 'PyOS_Readline uses single lock'
updated_at = <Date 2020-06-25.09:46:44.182>
user = 'https://github.com/albertz'

bugs.python.org fields:

activity = <Date 2020-06-25.09:46:44.182>
actor = 'vstinner'
assignee = 'none'
closed = True
closed_date = <Date 2020-06-25.09:46:44.184>
closer = 'vstinner'
components = []
creation = <Date 2011-08-30.17:15:54.957>
creator = 'Albert.Zeyer'
dependencies = []
files = []
hgrepos = []
issue_num = 12861
keywords = []
message_count = 6.0
messages = ['143229', '143231', '143257', '143386', '143394', '372330']
nosy_count = 3.0
nosy_names = ['amaury.forgeotdarc', 'vstinner', 'Albert.Zeyer']
pr_nums = []
priority = 'normal'
resolution = 'out of date'
stage = 'resolved'
status = 'closed'
superseder = None
type = None
url = 'https://bugs.python.org/issue12861'
versions = ['Python 2.7']

[albertz]

In Parser/myreadline.c PyOS_Readline uses a single lock (_PyOS_ReadlineLock). I guess it is so that we don't have messed up stdin reads. Or are there other technical reasons?

However, it should work to call this function from multiple threads with different/independent sys_stdin / sys_stdout.

[albertz]

Ok, it seems that the Modules/readline.c implementation is also not really threadsafe... (Whereby, I think it should be.)

[albertz]

Even more problematic: The readline lib itself is absolutely not designed in a way to be used from multi threads at once.

[amauryfa]

Well, readline is supposed to be used with a console, and there is only one usually. Why would you want to use readline from multiple threads?

[albertz]

You might have opened several via openpty.

I am doing that here: https://github.com/albertz/PyTerminal

[vstinner]

No activity for 9 years, I close the issue as out of date.