[Patches] [ python-Patches-1524639 ] Fix Tkinter Tcl-commands memory-leaks

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Patches item #1524639, was opened at 2006-07-18 18:00
Message generated for change (Comment added) made by loewis
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Category: Tkinter
Group: Python 2.5
Status: Open
Resolution: None
Priority: 5
Submitted By: Graham Horler (grahamh)
Assigned to: Martin v. Löwis (loewis)
Summary: Fix Tkinter Tcl-commands memory-leaks

Initial Comment:
Fix 8 memory-leaks by cleaning up created Tcl commands
automatically.

I attach a patch against Tkinter 47021.

=== Long explanation ===

I was bitten by a memory leak in Tkinter - 25MB per day
on a long-running process.  A net search found a couple
unrelated Tkinter leaks, and gave me some clues. 
Investigation using the tracing feature in tkleak.py
(see link) found the bug.

I searched for more similar leaks, and fixed them too.

The reasoning for patch #1121234 gives the reason for
the changes to _register() and deletecommand().

See http://www.uk.debian.org/~graham/python/tkleak.py
for my leak tracing and test script.


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>Comment By: Martin v. Löwis (loewis)
Date: 2006-07-24 08:15

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The patch looks wrong. Why are you deleting the _tkcommands
of the master widget if the variable is deleted? The master
could live much longer, and the commands might still be needed.

What is the purpose of the changes to trace_variable? You
are supposed to invoke trace_vdelete to release the callback.

Why are you catching TclError in so many cases? Under what
circumstances can you even get an error?

I think I would prefer if this patch was split into many
individual ones, each one fixing only a single bug (assuming
there are multiple bugs in Tkinter).

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Comment By: Graham Horler (grahamh)
Date: 2006-07-19 12:33

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I fixed a bug in the original patch: when destroying a
window which had Variable instances attached which in turn
had trace commands bound, Tkinter.py was trying to delete
the commands twice, as the command was mentioned in Variable
instance _tclCommands and _root()._tcl_Commands.

Also fixed 4 more leaks occurring when TclError is raised
after a callback has been created.

I have added 6 tests to tkleak.py to test the additional 4
fixes.

The patch is against 50704, hope it helps.

Thanks for your hard work, and for accepting my other
Tkinter.py patch.


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Comment By: Graham Horler (grahamh)
Date: 2006-07-18 18:18

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The python version I am using in production is 2.1 (for
historical reasons), however the memory leak bugs are in 2.1
through to 2.5.

I can generate a patch against any of the older versions
(e.g. 2.4) if anyone is interested.


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