[bugs #8374] NSNotificationCenter can deadlock

[Willem Rein Oudshoorn]

This mail is an automated notification from the bugs tracker
 of the project: GNUstep.




/**************************************************************************/
[bugs #8374] Full Item Snapshot:

URL: <http://savannah.gnu.org/bugs/?func=detailitem&item_id=8374>
Project: GNUstep
Submitted by: Willem Rein Oudshoorn
On: Tue 03/30/04 at 13:13

Category:  Base/Foundation
Severity:  3 - Ordinary
Item Group:  Bug
Resolution:  None
Assigned to:  None
Status:  Open


Summary:  NSNotificationCenter can deadlock

Original Submission:  There is a lock protecting the list of notifications.  
This lock is grabbed before sending the notifications and released after 
sending the notifications.  

This can lead to a deadlock when multiple threads are using the notification 
center.   The attached program shows in a very artificial situation how the 
deadlock can occur.  

I just spend 3 days figuring this out in a complicated situation involving 
multiple threads, DO and launched tasks.  
So it is not just a theoretical problem.

I have not looked deeply at it, but probably just
making a copy instead of maintaining the lock will solve it.
(But I have to look again.)


Wim Oudshoorn





File Attachments
-------------------

-------------------------------------------------------
Date: Tue 03/30/04 at 13:13  Name: deadlocktest.tar.gz  Size: 837KB   By: wim
Example of NSNotificationCenter deadlock.  
http://savannah.gnu.org/bugs/download.php?item_id=8374&amp;item_file_id=1143






For detailed info, follow this link:
<http://savannah.gnu.org/bugs/?func=detailitem&item_id=8374>

_______________________________________________
  Message sent via/by Savannah
  http://savannah.gnu.org/