[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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