openjdk,icedtea - Xmx option mandatory

[Roberto Mannai]

Hi
A quick update.

On 8/11/08, Mark Wielaard <mark at klomp.org> wrote:
> Hi Roberto,
> In one of your traces that you posted at:
> https://bugzilla.novell.com/show_bug.cgi?id=414462
> You see that the java launcher tries to allocate (mmap2)
> 603979776 bytes aka 576 MB on your machine, just before the failure,
> which you clearly don't have.

I started to debug the JVM, and the wrong result can be read into:
openjdk/hotspot/src/share/vm/memory/genCollectedHeap.cpp:193

When looping for three times, I have:
print total_reserved
         0
print total_reserved
  41287680 = 39,375 mb
print total_reserved
 603979776 = 576mb
print _n_gens
2

The lines are the following:
 for (int i = 0; i < _n_gens; i++) {
   total_reserved += _gen_specs[i]->max_size();
*** break and print total_reserved ***
   if (total_reserved < _gen_specs[i]->max_size()) {
     vm_exit_during_initialization(overflow_msg);
   }
   n_covered_regions += _gen_specs[i]->n_covered_regions();
 }

The problem seems related to the generations. I'll continue the analysis.

Ciao
Roberto Mannai

>
> If you could help us figure out where/what precisely is guessing
> something wrong for your setup that would be nice. I don't immediately
> have a suggestion. But start by tracing which of the os::*memory()
> functions in openjdk/hotspot/src/os_cpu/*/vm/os_*.cpp are called and
> what they return in your setup would be a good start.
>
> There seems to be a second bug during the cleanup after the abort
> because of too limited memory. That is the "** glibc detected *** java:
> free(): invalid pointer" you are seeing. Something is probably freeing
> something that was never allocated in this case.
>
> Cheers,
>
> Mark
>
>