On 5/6/2018 10:03 AM, Chris Angelico wrote:
On Sun, May 6, 2018 at 6:54 PM, Terry Reedy <tjre...@udel.edu> wrote:
Is it ALL of Tkinter that fails in threaded mode?
No. It is non-threaded tcl that fails in threaded mode, along with
tkinter's attempt to make non-thread tcl work anyway. There are at least
two different cases.
Ivan has clarified the following.
1. Tcl has a 'threads' compile switch.
2. The default changed from 'off' for 8.5 and before to 'on' for 8.6.
3. When compiled with thread support, the resulting library file has t
suffix.
Okay, that makes a HUGE difference. Thank you for clarifying. So, in
theory, threads SHOULD be supported, which means that bug reports of
the nature of "this fails in threaded mode" are 100% valid.
If the reported code does not have bugs, including thread deadlock and
shutdown bugs, which are non-trivial to avoid, yes.
I dug up more information. Though he did not say so, Ivan's first
issue, https://bugs.python.org/issue33257, reopens and continues
https://bugs.python.org/issue11077, using a slightly modified version of
the original ballistic launch example. Ivan added discussion of the tcl
thread-support compile switch, which was not mentioned in the original.
Ditto for a patch.
The originator of the original, Scott M., taught new programmers how to
display data from multiple sources, some blocking. It seemed most
natural to him and students to use threads to access sources and use the
documented widget.method(*args) APIs to display data, rather than have
to invent a protocol to pass such calls through a queue. See the
initial message.
In that older issue, I mentioned, as I did in response to Ivan, that
'thread' does not appear in the tkinter docs. Martin Löwis replied
"My claim is that Tkinter is thread-safe as it stands. A lot of thought
has been put into making Tkinter thread-safe, so if there is any claim
to the contrary, we would need more details: what exact Python version
is being used, what exact operating system is being used, what exact
code is run, and what exact output is produced."
and later said "It's supported on Unix since 1.5.1, and on Windows since
2.3."
If it were up to me, I would deprecate non-threaded mode immediately,
Given that 99% of tkinter users do not need threaded tcl, why cut some
of them off? When tkinter is import and a root is created, tkinter
cannot know whether the user is going to later make failing calls from
threads. Tkinter has traditional been slow to remove support of old
versions; it still supports 8.4. It will eventually become a moot
point, at least on Windows, as current Windows installers install
threaded tcl. I presume the same is true for the new Mac installers. I
have no idea what people have on linux.
--
Terry Jan Reedy
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