G1gc compaction algorithm

[Thomas Schatzl]

Hi,

On Tue, 2014-07-29 at 06:27 +0300, Martin Makundi wrote:
> Hi!
> 
> 
> We suffered a couple of Full GC's using regionsize 5M (it seems to be
> exact looking at logged actual parameters) and we tried the 16M option
> and this resulted in more severe Full GC behavior.
> 
> 
> Here is the promised log for 16 M
> setting: http://81.22.250.165/log/gc-16m.log
> 
> 
> We switch back to 5M hoping it will behave more nicely.

About the 5M region size issue: the VM you use does not update the
parameters. That has been fixed only later. However other log messages
give away the true region size (from log/gc.log):

{Heap before GC invocations=1 (full 0):
 garbage-first heap   total 20971520K, used 381687K [0x00007f1530000000, 0x00007f1a30000000, 0x00007f1cb0000000)
***region size 4096K***, 94 young (385024K), 3 survivors (12288K)
 compacting perm gen  total 524288K, used 13875K [0x00007f1cb0000000, 0x00007f1cd0000000, 0x00007f1cd0000000)
   the space 524288K,   2% used [0x00007f1cb0000000, 0x00007f1cb0d8cfd8, 0x00007f1cb0d8d000, 0x00007f1cd0000000)

:)

Thanks,
  Thomas