[Gc] Problems with GC performance using gcj

Bruce Hoult bruce at hoult.org
Tue Jan 11 17:18:52 PST 2011


On Sat, Jan 8, 2011 at 4:16 AM, Ben Keppler <bkeppler at tridentms.com> wrote:

>  Alternatively, are there settings on the Boehm GC that might relieve our
> problems?  I would appreciate any information you could provide.
>

You also don't say what settings you're using now, or give any hint about
the characteristics of your application.

Things that can often make a big difference to overall throughput (but not
pause times) at the expense of heap size include:

  GC_use_entire_heap = 1;
  GC_free_space_divisor = 2;

Things that can make a big difference to pause times
include GC_all_interior_pointers = 0 and using GC_malloc_atomic() instead of
GC_malloc() as much as possible, especially if a large fraction of your live
data is strings, sounds, images or the like that don't need to be scanned
for pointers.

I don't know whether GCJ is using GC_malloc_atomic() for String,
StringBuffer, byte[], short[], int[]. long[], float[], double[] but it
certainly should be.
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