[ python-Bugs-1442493 ] IDLE shell window gets very slow when displaying long lines

Wed Jul 26 19:56:46 CEST 2006

Bugs item #1442493, was opened at 2006-03-03 16:45
Message generated for change (Comment added) made by taleinat
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Category: IDLE
Group: Python 2.4
Status: Open
Resolution: Wont Fix
Priority: 5
Submitted By: Heiko Selber (drhok)
Assigned to: Nobody/Anonymous (nobody)
Summary: IDLE shell window gets very slow when displaying long lines

Initial Comment:
I wrote a little python script that prints a large 
dictionary to stdout (simply using 'print 
mydictionary').

In fact, the type is irrelevant, what matters is that 
the resulting output had approx. 200,000 characters.

The shell prints the dictionary into a single line, 
which causes the window to be almost non-responding, 
e.g. when I try to scroll the window.

Even on a high-end PC it takes a minute or even 
longer to react to anything.

I use Python 2.4.2 on Windows XP SP2.

I am aware that it is not exactly wise to print such 
large objects, but I usually print return values to 
stdout when I debug a script, and I do not always 
expect an object to be that large.

The average text editor handles such long lines much 
better.

A quick workaround might be to break very long lines 
automagically (perhaps at around column 1000).

PS: I already observed the bug some years ago. I 
think I even submitted it to python or idlefork a 
long time ago but I was unable to find it in the 
buglist.

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Comment By: Tal Einat (taleinat)
Date: 2006-07-26 20:56

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The Squeezer extension works like a charm! It's also been
thoroughly tested by tens of users over the past several years.

Why not include it as one of the default extensions, and
have it enabled by default?

BTW I have a tweaked version of Squeezer (I fixed the line
counting code), if you're interested.

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Comment By: Kurt B. Kaiser (kbk)
Date: 2006-03-29 22:52

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It's not that I don't consider it an issue, but I can't
do anything to improve the performance of the Tk text
widget.  IDLE is pure Python.

One thing that comes to mind is to set a maximum line 
length.  If the line exceeds that, print line(:(MAX -100)
+ '...' + line(:-100)  instead of printing the whole thing
which no one wants to look at anyway.

Another thing I've wanted to do is provide the ability
to clear the shell window when it gets too full, w/o
restarting IDLE.

Yes, you might ask the tkinter guys on their mail list,
I'd be interested in hearing their reply.

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Comment By: Josiah Carlson (josiahcarlson)
Date: 2006-03-29 22:35

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You can close the window which includes the Shell that has
the huge output, or even reduce the priority of your Idle
shell (you can make it automatic by mucking about with the
shortcut; see the 'start' command).

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Comment By: Heiko Selber (drhok)
Date: 2006-03-29 22:19

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Hi kbk,

well, my use case is debugging. I write a script and run it
with IDLE. It doesn't behave as expected, so I insert a
print statement. Next time I run it, IDLE hangs. Oops, it
was a long array; it should have been an int. Line too long.
Duh.

OK, I wait through it, correct the bug, run it again. What
happens? IDLE hangs again, trying to scroll a long line (of
the previous run).

Never mind, I can always kill the process... Dammit, I
can't! It eats 100% CPU; task manager doesn't respond.

IMHO his takes away one of python's strengths, which is
making quick hacks really quick.

Would you suggest redirecting this issue to tkinter? You
don't seem to consider this an issue at all.

I will give squeezer a try. Or maybe PyDev?

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Comment By: Kurt B. Kaiser (kbk)
Date: 2006-03-29 01:08

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This is a known problem with Tk/Tcl/tkinter - large output 
scrolls slowly. It's not something that can be fixed in IDLE.  I 
tried it on Arch Linux - IDLE 2.5a0 - Tk 8.4.  250,000 character 
output not too bad , 25 sec, but 10,000 lines of 25 char takes 
over twice that long, so breaking the lines doesn't help.

I don't see any response problem once the output completes.  The 
situation is exponentially worse at 500,000 char.

What is your use case?  IDLE is designed to be an IDE.  Why 
output such massive data?

You may be interested in Squeezer, a Noam Raphael extension to 
IDLEfork.

http://sourceforge.net/tracker/index.php?
func=detail&aid=704316&group_id=9579&atid=309579

I haven't tried it myself, but it might be what you're looking 
for.

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Comment By: Josiah Carlson (josiahcarlson)
Date: 2006-03-10 22:18

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Generally speaking, most wrapping text controls have issues
with wrapping long lines.  It would seem reasonable to get
the width of the text control in characters, and manually
wrap all incoming lines regardless.  If the existance or not
of real line endings are important, one could mark which
lines are manually wrapped and remove the line endings on
copy (edit->copy, ctrl+c, etc.).

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Comment By: Terry J. Reedy (tjreedy)
Date: 2006-03-10 01:45

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I verified this with print 100000*'a', also XP (home) sp2.
The sluggishness continued after getting the prompt back 
and trying to do something simple, like 2+2, taking maybe 
1/2 minute to print 4 and then the >>> prompt again.
The sluggishness *also* continued after restarting the 
shell (^F6).  This indicates that the problem is with the 
window, not with IDLE.  Hope someone can try same on *nix 
system to see if general with TKinter or specific to Win 
systems.

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