Re: big memory leak in GSString

[Pirmin Braun]

Am Tue, 8 Jan 2013 09:43:22 +0100
schrieb Fred Kiefer <address@hidden> :

> The behaviour in GNUstep is just as you describe, but this shouldn't lead to 
> a real memory leak. The original string still will get released when the 
> substrings get released. If the livespan of these strings should really be 
> different, the best you can do is to copy the substring and work with the 
> copy. This cuts the connection to the underlying parent.
> 

ok, tried this:
#import <Foundation/Foundation.h>

int
main(int argc, char **argv)
{
    NSString *s = @"fi-rst|sec-ond|thi-rd",*s1,*s2;
    NSArray *a,*a1;
    NSAutoreleasePool *pool =[NSAutoreleasePool new];

    a = [s componentsSeparatedByString:@"|"];
    s1 = [a objectAtIndex:0];

    NSLog(([NSString stringWithFormat:@"a %@ has retainCount of %i",s1,[s1 
retainCount]]));

    a1 = [s1 componentsSeparatedByString:@"-"];
    NSLog(([NSString stringWithFormat:@"b %@ has retainCount of %i",s1,[s1 
retainCount]]));

    s2 = [[a1 objectAtIndex:0]copy];
    [s2 retain];
    NSLog(([NSString stringWithFormat:@"c %@ has retainCount of %i",s1,[s1 
retainCount]]));

    [s1 retain];
    NSLog(([NSString stringWithFormat:@"after [s1 retain]: %@ has retainCount 
of %i",s1,[s1 retainCount]]));


    [pool release];

    NSLog(([[NSString alloc]initWithFormat:@"after [pool release]: %@ has 
retainCount of %i",s1,[s1 retainCount]]));

    exit (0);
    return 0;
}


result on GNUStep:
2013-01-08 15:21:24.808 TestTool[30229] a fi-rst has retainCount of 2
2013-01-08 15:21:24.809 TestTool[30229] b fi-rst has retainCount of 4
2013-01-08 15:21:24.809 TestTool[30229] c fi-rst has retainCount of 4
2013-01-08 15:21:24.809 TestTool[30229] after [s1 retain]: fi-rst has 
retainCount of 5
2013-01-08 15:21:24.809 TestTool[30229] after [pool release]: fi-rst has 
retainCount of 1

so this works;


then implemented a new NSString Category method for the real world App:
- (NSArray *)copiedComponentsSeparatedByString:(NSString *)s;
{
    NSArray *a = [self componentsSeparatedByString:s];
    NSMutableArray *ma = [NSMutableArray arrayWithCapacity:[a count]];
    int i,j;

    // deep copy of a
    for(i=0,j=[a count];i<j;i++){
        NSString *s1 = [[a oai:i]copy];

        [ma addObject:s1];
        [s1 release]; // s1 only retained by ma which is autoreleased
    }
    return [NSArray arrayWithArray:ma]; // immutable
}

but unfortunately no impact on memory consumption;
background of all this: when creating a certain object by parsing a string it 
takes 200 MB more than instantiating it out of an formerly archived instance 
using NSArchiver/NSUnarchiver 


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