[Gc] gc leaking?

Hans Boehm Hans.Boehm at hp.com
Tue Jun 22 20:30:03 PDT 2004


I don't recognize the code that your debug log refers to.  This is
line 235 in which file?

Thanks.

Hans

On Sun, 20 Jun 2004, Joseph Gebis wrote:

>
> I'm running gc 2.6 on a Xeon, uname -a gives:
> Linux x49 2.4.24-lustre.1.0.4-perfctr.2.6.6-mppe #1 SMP Wed Apr 21
> 21:17:28 PDT 2004 i686 GNU/Linux
>
>
> I installed the garbage collector to find some memory leaks
> in my program.  I #define'd GC_DEBUG in my source code, and
> called GC_MALLOC and GC_FREE directly (and never malloc or
> free).  Usually, when it found a leak, it would report it
> with something that looked like this:
>
> Leaked composite object at 0x80a6b78 (loop.c:16, sz=4)
>
> After fixing all of the leaks with source code refences (a
> job made much easier with GC -- thanks!), I was left with some leaks
> like this:
>
> Leaked composite object at start: 0x8083000, appr. length: 64
>
> (no source code reference).
>
> To try to discover the source of the leak, I ran gdb on my
> program.  It appears to me that that memory location
> is referring to some location interal to GC:
> ---
> 235       s = (struct Stream *)GC_MALLOC(sizeof(struct Stream));
> (gdb) p s
> $7 = (struct Stream *) 0x40196510
> (gdb) p *0x8083000
> Cannot access memory at address 0x8083000
> (gdb) n
> 236       if(s == NULL) {
> (gdb) p s
> $8 = (struct Stream *) 0x8081fb8
> (gdb) p *0x8083000
> $9 = 0
> ---
>
> To check if my program did have a memory leak, I compiled a
> version of my program without GC (using regular malloc and
> free), that repeatedly loops over the main body of allocating
> and freeing memory structures.  No matter how long I let
> that run, it does not grow in memory size.  My program is
> single-threaded.
>
> I guess I have a few questions:
> 1) Is this a leak in GC, or is it really a leak in my program
>    that I'm somehow missing?
> 2) If it is a leak in my program, why aren't source code references
>    printed for these leaks, while they were for my other leaks?
>
>
> Thank you.
>
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