[projects] tree crashes/hangs app on Vista

[GoogleCodeExporter]

To reproduce the crash (happens on delete):

1. open an empty project
2. create "untitled folder"
3. create "untitled folder"\"untitled folder"
4. delete "untitled folder"\"untitled folder"
5. delete "untitled folder"
6. crash 
NOTE: tested with old and new recycler module.

To reproduce the hang (happens with no apparent trigger)

1. open a project
2. start creating folder, subfolders and files
3. click on them
4. repeat until app hangs. Sometimes it takes a couple of clicks, sometimes
it doesn't happen.
5. Maybe related: when you create a new folder (on Vista), the tree doesn't
refreshes (no [+] to the right of the parent node) until you click
somewhere (or change the focus to another application)

I attach some trivial trace I took "instrumenting" the code with prints. 
I think I got the point where the app crashes (I reproduced an identical
trace 3 times). The trace taken when the app hangs, instead, it's not
really useful. I attach it just FYI.

Original issue reported on code.google.com by rudi.pet...@gmail.com on 2 Feb 2009 at 10:23

Attachments:

• trace-crash-after-delete.txt
• trace-hang-nodelete.txt

[GoogleCodeExporter]

hello, is this the same as issue 88 or is there something differen't about this 
one?

Original comment by CodyPrec...@gmail.com on 3 Feb 2009 at 1:27

[GoogleCodeExporter]

Hello. Different one. That one (88) happened on XP. This one (these two 
actually)
happens on Vista  and the crash here is a real crash (python.exe crash, editra 
killed
by the OS) with no traceback. 

Maybe the issues are correlated. I'll check at home on Vista with the update 
you made
today.

Original comment by rudi.pet...@gmail.com on 3 Feb 2009 at 2:35

[GoogleCodeExporter]

No, the issue persists on Vista. 

1. open an empty project
2. create "untitled folder"
3. create "untitled folder"\"untitled folder"
4. delete "untitled folder"\"untitled folder"
5. delete "untitled folder"
6. python.exe crash (status code: 0xC0000005, that is access violation)

The trace shows that tree.delete(node) in OnsyncNode is the offending 
instruction
(100% reproducible on VISTA)

C:\Users\rd\src\editra>python launcher.py
BEGIN onPopupNewFolder
BEGIN OnSyncNode
END OnSyncNode
BEGIN onPopupNewFolder
BEGIN OnSyncNode
END OnSyncNode
BEGIN OnSyncNode
END OnSyncNode
BEGIN OnSyncNode
END OnSyncNode
delete(). selections = [(<wx._controls.TreeItemId; proxy of <Swig Object of type
'wxTreeItemId *' at 0x5081dc8> >
, u'C:\\Users\\rd\\Desktop\\vistaproj\\Untitled Folder\\Untitled Folder')], 
thread
start with target  delete...
BEGIN delete()
BEGIN OnSyncNode
END OnSyncNode
BEGIN OnSyncNode
OnSyncNode(): for item in deleted, deleted = [u'Untitled Folder'], item = 
Untitled Folder
OnSyncNode(): self.tree.ItemHasChildren(node)
OnSyncNode() calling: "tree.delete(node)"
OnSyncNode() called: "tree.delete(node)"
END OnSyncNode
getMTime Error: [Error 3] The system cannot find the path specified:
u'C:\\Users\\rd\\Desktop\\vistaproj\\Untitle
d Folder\\Untitled Folder\\*.*'
BEGIN OnSyncNode
END OnSyncNode
BEGIN OnSyncNode
END OnSyncNode
delete(). selections = [(<wx._controls.TreeItemId; proxy of <Swig Object of type
'wxTreeItemId *' at 0x515be88> >
, u'C:\\Users\\rd\\Desktop\\vistaproj\\Untitled Folder')], thread start with 
target 
delete...
BEGIN delete()
BEGIN OnSyncNode
OnSyncNode(): for item in deleted, deleted = [u'Untitled Folder'], item = 
Untitled Folder
OnSyncNode(): self.tree.ItemHasChildren(node)
OnSyncNode() calling: "tree.delete(node)"
getMTime Error: [Error 3] The system cannot find the path specified:
u'C:\\Users\\rd\\Desktop\\vistaproj\\Untitled Folder\\*.*'
getMTime Error: [Error 3] The system cannot find the path specified:
u'C:\\Users\\rd\\Desktop\\vistaproj\\Untitled Folder\\Untitled Folder\\*.*'

C:\Users\rd\src\editra>

Isnt't deleting the node from the wrong thread?

Original comment by rudi.pet...@gmail.com on 3 Feb 2009 at 4:15

[GoogleCodeExporter]

No, the deletion is happening in an event handler, events are only processed on 
the 
main thread ( you can verify this by putting a 'print wx.Thread_IsMain()' ).

An access violation error would suggest that the c++ code underneith is trying 
to 
access some memory that has already been deleted or is otherwise corrupt. Here 
are a 
couple of issues that I can think of that may be at fault here.

1) Each directory node has a watcher thread attached to it. These should 
probably be 
stopped before deleting the node to prevent them from sending further sync 
events. 
As I can see from your trace the getMTime calls from the watcher thread(s) are 
are 
still running after the node has been removed.

2) The nodes that show up in the 'deleted' list of OnSyncNodes should probably 
be 
ordered to find which ones are parent->children and make sure they are deleted 
in 
the proper order. i.e) parent.DeleteChildren() first, then make sure we dont' 
try to 
delete any nodes that may have been under there.

I would think that this would already be the case but will need checking.

Cody

Original comment by CodyPrec...@gmail.com on 3 Feb 2009 at 4:31

• Changed state: Accepted

[GoogleCodeExporter]

Yes that thread seems to run forever. If you create a folder, delete it, and 
then
watch the trace, you'll see that it "stat" that file forever.
Anyway notice that the crash happens on tree.delete()

 ...
 OnSyncNode(): self.tree.ItemHasChildren(node) 
 OnSyncNode() calling: "tree.delete(node)"
  >> crash here <<
  >> kill app clicking on windows crash msgbox << 
 getMTime for C:\Users\rd\Desktop\vistaproj\Untitled Folder
 getMTime Error: [Error 3] The system cannot find the path specified:
u'C:\\Users\\rd\\Desktop\\vistaproj\\Untitled Folder\\*.*'

C:\Users\rd\src\editra>

Original comment by rudi.pet...@gmail.com on 3 Feb 2009 at 5:39

[GoogleCodeExporter]

Ok,

A simple test that you try then is to add a check for if the 'self.path' still 
exists at the top of the loop in WatcherThread.run and return if it does not, 
to 
stop the thread.

OnSyncNodes should probably also check to see if the 'parent' node is in 
the 'deleted' list. Then do something like the following if it is.

data = self.tree.GetPyData(parent)
if 'watcher' in data:
    data['watcher'].flag = False

This should force the thread to exit within the next second.

Cody

Original comment by CodyPrec...@gmail.com on 3 Feb 2009 at 6:09

[GoogleCodeExporter]

Yes checking the path in WatcherThread.run stops it. 
It seems I found a way to stop the crash happening. After reading this 9 months 
old
thread about a subtle bug on Vista related to tree selection and deletion:

http://thread.gmane.org/gmane.comp.lib.wxwidgets.devel/98918

I decided - out of any logic - I could call tree.UnselectNode on the node being
deleted, and this way it stops crashing. Maybe it's just luck, but these 
specific 
use-case cannot be reproduced after applying the patch.

I attach a patch but maybe should need some testing and be applied only on 
Vista (I
don't know if it can trigger some side-effects. I don't think so because you 
are to
deleting it anyway)

Original comment by rudi.pet...@gmail.com on 3 Feb 2009 at 8:54

[GoogleCodeExporter]

forgot the patch

Original comment by rudi.pet...@gmail.com on 3 Feb 2009 at 8:54

Attachments:

• issue89.patch

[GoogleCodeExporter]

Thanks,

applied. Except for the check in the thread. Now that I think about it this may 
need 
to be handled in the OnSync or OnCollapse handler so that the thread is 
properly 
deleted from the watchers map in the project pane. Will try to check in those 
changes tonight.

Cody

Original comment by CodyPrec...@gmail.com on 3 Feb 2009 at 10:58

• Changed state: Fixed
• Added labels: OpSys-Windows