heap expanded after young gen gc?

[Ion Savin]

Hi,

 From the GC log below it seems that the heap gets expanded after young 
gen collection also (131008K total at 0.030 got expanded to 262080K 
total at 0.184). I was under the impression that this happens only 
during Full GC (which might be triggered by the need to resize).

0.030: [GC [PSYoungGen: 128K->64K(192K)] 128K->128K(131008K), 0.0005310 
secs] [Times: user=0.00 sys=0.00, real=0.00 secs]

0.184: [GC [PSYoungGen: 138K->64K(192K)] 261932K->261881K(262080K), 
0.0021120 secs] [Times: user=0.01 sys=0.00, real=0.01 secs]

0.186: [Full GC [PSYoungGen: 64K->0K(192K)] [PSOldGen: 
261817K->122K(130816K)] 261881K->122K(131008K) [PSPermGen: 
2552K->2552K(21248K)], 0.0110530 secs] [Times: user=0.01 sys=0.01, 
real=0.01 secs]

0.297: [GC [PSYoungGen: 2K->32K(192K)] 261854K->261883K(262080K), 
0.0013380 secs] [Times: user=0.00 sys=0.00, real=0.00 secs]

If expansion can happen after a young gen collection how is the 
-XX:MinHeapFreeRatio (and -XX:MaxHeapFreeRatio) flag interpreted given 
that after young gen GC objects might get promoted to the tenured 
generation filling up the heap above the min ratio?

The heap is sized like this: -Xms128m -Xmx256m -Xmn256k
And the app is just generating collectable junk in a loop.

What I would expect to happen is for the heap to fill up to 128m, a full 
gc to happen and since the old gen free space is over the default 40% 
min heap free before expansion no heap resize to happen.

Please advise. Thank you!

Regards,
  Ion Savin