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[bug #6743] Distinct NSNumbers with the same value dealloc each other
From: |
nobody |
Subject: |
[bug #6743] Distinct NSNumbers with the same value dealloc each other |
Date: |
Tue, 25 Nov 2003 06:09:51 -0500 |
User-agent: |
Mozilla/5.0 (Windows; U; Windows NT 5.0; en-US; rv:1.5) Gecko/20031007 |
=================== BUG #6743: LATEST MODIFICATIONS ==================
http://savannah.gnu.org/bugs/?func=detailbug&bug_id=6743&group_id=99
Changes by: David Ayers <d.ayers@inode.at>
Date: Tue 11/25/2003 at 12:09 (Europe/Vienna)
------------------ Additional Follow-up Comments ----------------------------
Yes, that would be very good.
=================== BUG #6743: FULL BUG SNAPSHOT ===================
Submitted by: moseshall Project: GNUstep
Submitted on: Tue 11/25/2003 at 04:06
Category: Base/Foundation Severity: 5 - Major
Bug Group: Bug Resolution: None
Assigned to: None Status: Open
Summary: Distinct NSNumbers with the same value dealloc each other
Original Submission: Distinct NSNumbers with the *same value* can dealloc each
other. The following code snippet crashes gnustep-base 1.7.3 possibly because
of NSNumber caching. If I don't call [n1 release] there is no crash. If this is
due to caching strategy, then it can make NSNumber very fragile when numbers
are expected to persist as long as retained.
#include <Foundation/Foundation.h>
int main (int argc, const char *argv[], const char *env[])
{
NSNumber* n1 = [NSNumber numberWithLong:1];
NSNumber* n2 = [NSNumber numberWithLong:1];
NSLog(@"%@(%d)n", n1, [n1 retainCount]);
NSLog(@"%@(%d)n", n2, [n2 retainCount]);
[n1 release]; //<--problem here
// The next line crashes. n2 has gone away!
NSLog(@"%@(%d)n", n2, [n2 retainCount]);
return 0;
}
Thanks for your attention.
Brian 'Moses' Hall
moses@blugs.com
Follow-up Comments
*******************
-------------------------------------------------------
Date: Tue 11/25/2003 at 12:09 By: ayers
Yes, that would be very good.
-------------------------------------------------------
Date: Tue 11/25/2003 at 11:40 By: CaS
What I was thinking of was making the cached numbers members of some new
subclass where -dealloc had been overridden to raise an exception. So there
would be no runtime overhead on dealloc of a non-cached number.
-------------------------------------------------------
Date: Tue 11/25/2003 at 11:17 By: ayers
In principal I agree, but it depends on the cost. I'm not sure how much the
hit would be, but expect numbers to be created and destroyed often in GDL2
based applications. So if each dealloc resulted in a hash look up... well,
depending on the implementation, I guess we may need to test it.
-------------------------------------------------------
Date: Tue 11/25/2003 at 09:00 By: CaS
I think raising an exception upon an attempt to deallocate a cached NSNumber
would be a nice feature.
-------------------------------------------------------
Date: Tue 11/25/2003 at 07:24 By: CaS
There is a bug in the test program ... it releases an object it does not own,
so a crash does not seem unreasonable (in the general case releasing objects
you don't own is bound to cause crashes).
Is the report a suggestion that the library should be changed to crash
elsewhere, or to have code added to watch for this case and raise an exception
or something similar, or perhaps to simply ignore the extra release and keep on
going?
CC list is empty
No files currently attached
For detailed info, follow this link:
http://savannah.gnu.org/bugs/?func=detailbug&bug_id=6743&group_id=99
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- [bug #6743] Distinct NSNumbers with the same value dealloc each other, nobody, 2003/11/24
- [bug #6743] Distinct NSNumbers with the same value dealloc each other, nobody, 2003/11/25
- [bug #6743] Distinct NSNumbers with the same value dealloc each other, nobody, 2003/11/25
- [bug #6743] Distinct NSNumbers with the same value dealloc each other, nobody, 2003/11/25
- [bug #6743] Distinct NSNumbers with the same value dealloc each other,
nobody <=
- [bug #6743] Distinct NSNumbers with the same value dealloc each other, nobody, 2003/11/25
- [bug #6743] Distinct NSNumbers with the same value dealloc each other, nobody, 2003/11/25
- [bug #6743] Distinct NSNumbers with the same value dealloc each other, nobody, 2003/11/25
- [bug #6743] Distinct NSNumbers with the same value dealloc each other, nobody, 2003/11/25