SynEdit with memory leak?

[JRadke 0]

I use SynEdit as replacement for TMemo to list permanent incoming data. To prevent a memory overflow I limit the number of rows like this:

Synedit1.Lines.Add('My new data...');
if SynEdit1.Lines.Count > 150 then SynEdit1.Lines.Delete(0);

This will limit the number of rows to 150, but the allocated memory is not released by the Delete command (checked with memoryManager), so at some point I get a memory overflow.

This behaviour happens since upgrading from Delphi 10.4 to Delphi 11 and SynEdit respectively (2022.03-11).

 

[pyscripter 694]

Assuming you are using the Turbopack Synedit:

 

Changes to the text buffer are undoable.   So just calling Delete does not clear all related memory.    You need to do one of:

• call ClearUndo every now and then to release the undo/redo memory.
• Set MaxUndo to some number to limit the undoable actions.  The default is 0 (unlimited undo/redo).
• call LockUndo/Unlock undo to prevent actions being added to the undo/redo stack (the most efficient).

If you still get a memory overflow then this is a bug that you should report.

 

Edited August 1, 2022 by pyscripter

[MarkShark 27]

My testing with MaxUndo = 1 (to most closely match a TMemo) doesn't show any leaks.  I've also tested the other scenarios with no leak issues that I could detect.  It's very true that the default settings can chew through a lot of memory for the undo stuff, so in the case of a log like this you must limit or manage the undo.  On a related note:  Am I correct that LockUndo/UnlockUndo must always be followed by a ClearUndo in order to keep everything in sync?  I wasn't' sure if that happened automatically or perhaps is just not an issue.

 

-Mark

 

@pyscripter

I'm very impressed by how few issues there have been for such a major rewrite!  Well done!

 

[pyscripter 694]

You can use LockUndo to disable Undo altogether.

LockUndo/UnlockUndo is also useful when you read a file or initially setup a text buffer.  If the Undo buffer is not empty then you would want to call ClearUndo before or after.

Edited August 1, 2022 by pyscripter

[JRadke 0]

Thank you for the answers.
The consideration of the undo/redo memory seems plausible to me, I will try that out.

 

-Jürgen