Long delay when using undo/redo in eclipse with Cygwin/X

Long delay when using undo/redo in eclipse with Cygwin/X

[Matt D.]

I'm not sure if this is the appropriate place to direct this question. 
Although the only case where I experience this is in eclipse, it only 
occurs when connecting to a remote X server.

When using ctrl-z (undo) and ctrl-shift-z (redo) in eclipse there is a 
significant delay in the X session where it appears to 'hang' for 
several seconds. Holding down ctrl-z causes the hangs to queue and can 
be seen by the carrot only being updated when the text area is clicked 
in between each hang.

The delay does NOT occur when eclipse is run locally on the machine; it 
only occurs with a remote X session. The X session is done over LAN so 
there is plenty of bandwidth available.

A delay does NOT occur when doing large amounts of drawing in the text 
area, such as ctrl-a (select-all), very large cuts (ctrl-x), or pasts 
(ctrl-v).

The delay does not appear to have any correlation to the size of the 
task being undone/redone. Undo on a single character has the same long 
delay as using undo after deleting everything in a source file.

The delay still occurs when using undo from the edit menu or after 
having been rebound to another key (ctrl-r for example).

Any suggestions?

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Re: Long delay when using undo/redo in eclipse with Cygwin/X

[Jon TURNEY]

On 12/06/2013 23:33, Matt D. wrote:
> I'm not sure if this is the appropriate place to direct this question.
> Although the only case where I experience this is in eclipse, it only occurs
> when connecting to a remote X server.
> 
> When using ctrl-z (undo) and ctrl-shift-z (redo) in eclipse there is a
> significant delay in the X session where it appears to 'hang' for several
> seconds. Holding down ctrl-z causes the hangs to queue and can be seen by the
> carrot only being updated when the text area is clicked in between each hang.
> 
> The delay does NOT occur when eclipse is run locally on the machine; it only
> occurs with a remote X session. The X session is done over LAN so there is
> plenty of bandwidth available.
> 
> A delay does NOT occur when doing large amounts of drawing in the text area,
> such as ctrl-a (select-all), very large cuts (ctrl-x), or pasts (ctrl-v).
> 
> The delay does not appear to have any correlation to the size of the task
> being undone/redone. Undo on a single character has the same long delay as
> using undo after deleting everything in a source file.
> 
> The delay still occurs when using undo from the edit menu or after having been
> rebound to another key (ctrl-r for example).
> 
> Any suggestions?

There are a couple of things you might try to isolate the problem:

- try running the X server with -noclipboard to rule out any interaction with
the Windows clipboard integration.
- try a remote X server running on Linux, not Windows

If it behaves the same in both those cases, it looks like something Eclipse is
doing (perhaps requiring excessive round-trips to the server) and a wireshark
capture might be informative.

-- 
Jon TURNEY
Volunteer Cygwin/X X Server maintainer

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