• Ben Hinkle (71/71) Aug 03 2005 Here's a useful hack for anyone using classes with "expensive" dtors. To...
• Sean Kelly (6/9) Aug 03 2005 Interesting idea. Expand the output a bit to mention class name on cons...
• Ben Hinkle (7/19) Aug 03 2005 It might be possible to hook into the LOGGING version in gcx that is use...

"Ben Hinkle" <bhinkle mathworks.com> writes:

Here's a useful hack for anyone using classes with "expensive" dtors. To 
help track dtor calls from the GC add the following lines at line 301 of 
src/phobos/internal/gc/gc.d (just inside new_finalizer)
 if (p && dummy == p) {
 ClassInfo **pc = cast(ClassInfo **)p;
 if (*pc) {
     for( ClassInfo c = **pc; c; c = c.base) {
            if (c.destructor) {
                printf("GC: ~%.*s(%p)\n",c.name,p);
                break;
            }
        }
    }
 }
and search through gcx.d for *finalizer and replace the null second 
arguments with p and recompile phobos.
Then when your program runs you can watch for any print statements to see 
just when your resources are getting cleaned up and if you need to worry 
about manually managing the resource. For example the test code

class Foo {
    byte[100000] big;
    ~this(){}
}
int main() {
    while(true) {
        printf("allocating\n");
        new Foo;
        printf("done allocating\n");
    }
    return 0;
}

produces on my machine

allocating
done allocating
allocating
done allocating
allocating
done allocating
allocating
done allocating
allocating
done allocating
allocating
done allocating
allocating
done allocating
allocating
GC: ~Foo(00892000)
GC: ~Foo(008AB000)
GC: ~Foo(008C4000)
GC: ~Foo(008DD000)
GC: ~Foo(008F6000)
GC: ~Foo(0090F000)
GC: ~Foo(00928000)
GC: ~Foo(0095A000)
done allocating
allocating
done allocating
allocating
done allocating

while if I explicitly delete in main

int main() {
    while(true) {
        printf("allocating\n");
        Foo x = new Foo;
        printf("done allocating\n");
        delete x;
    }
    return 0;
}

it no longer prints any GC traces. 

Sean Kelly <sean f4.ca> writes:

In article <dcqlg1$16jp$1 digitaldaemon.com>, Ben Hinkle says...
Here's a useful hack for anyone using classes with "expensive" dtors. To 
help track dtor calls from the GC add the following lines at line 301 of 
src/phobos/internal/gc/gc.d (just inside new_finalizer)

Interesting idea.  Expand the output a bit to mention class name on construction
plus the memory address the object is in for both and you could generate reports
from the output to see which objects are never destroyed.  Too bad there's no
easy way to get source file/line information in the display as well.


Sean

"Ben Hinkle" <bhinkle mathworks.com> writes:

"Sean Kelly" <sean f4.ca> wrote in message 
news:dcqn2s$17t2$1 digitaldaemon.com...
 In article <dcqlg1$16jp$1 digitaldaemon.com>, Ben Hinkle says...
Here's a useful hack for anyone using classes with "expensive" dtors. To
help track dtor calls from the GC add the following lines at line 301 of
src/phobos/internal/gc/gc.d (just inside new_finalizer)

 Interesting idea.  Expand the output a bit to mention class name on 
 construction
 plus the memory address the object is in for both and you could generate 
 reports
 from the output to see which objects are never destroyed.  Too bad there's 
 no
 easy way to get source file/line information in the display as well.

It might be possible to hook into the LOGGING version in gcx that is used 
for leak detection. I haven't recompiled with logging, though, so I don't 
know anything about it besides glancing through the code. It's true that it 
can be surprising what stuff hangs around from some non-obvious global 
reference.