Running with -verbosegc Option.

Question

Hi ,
Can any one explain each term, what does the following output means [while running with the option -verbosegc]
java -verbosegc test
[GC 510K->181K(1984K), 0.0066506 secs]
[GC 693K->342K(1984K), 0.0057084 secs]
[GC 854K->489K(1984K), 0.0109063 secs]
[GC 998K->581K(1984K), 0.0090856 secs]
[GC 1093K->602K(1984K), 0.0073623 secs]
[GC 1114K->738K(1984K), 0.0047804 secs]
[GC 1249K->1063K(1984K), 0.0099846 secs]
[GC 1562K->1528K(2112K), 0.0093059 secs]
[Full GC 1528K->1506K(2112K), 0.1076427 secs]
[GC 2015K->1998K(3088K), 0.0055318 secs]
[GC 2487K->2470K(3088K), 0.0060814 secs]
[GC 2981K->2963K(3600K), 0.0060281 secs]
[Full GC 2963K->2963K(3600K), 0.1152215 secs]
[GC 3632K->3615K(5516K), 0.0053477 secs]
[GC 4125K->4119K(5516K), 0.0052388 secs]
[GC 4619K->4596K(5516K), 0.0063873 secs]
[GC 5107K->5087K(5644K), 0.0086590 secs]
[Full GC 5087K->5087K(5644K), 0.1233247 secs]
[GC 5706K->5680K(9152K), 0.0545960 secs]
[GC 6313K->6158K(9152K), 0.0090305 secs]
[GC 6798K->6367K(9152K), 0.0113269 secs]
[GC 7007K->6397K(9152K), 0.0043400 secs]
[GC 7037K->6427K(9152K), 0.0022167 secs]
[GC 7131K->6588K(9152K), 0.0072012 secs]
[GC 7207K->7128K(9152K), 0.0101116 secs]
[GC 7752K->7725K(9152K), 0.0083363 secs]
[GC 8351K->8328K(9152K), 0.0073818 secs]
[GC 8964K->8940K(9664K), 0.0076883 secs]
[Full GC 8940K->4632K(9664K), 0.1903230 secs]
[GC 5269K->5257K(9152K), 0.0057223 secs]
[GC 5890K->5876K(9152K), 0.0179900 secs]
[GC 6506K->6481K(9152K), 0.0070621 secs]
[GC 7116K->7087K(9152K), 0.0076863 secs]
[GC 7727K->7668K(9152K), 0.0248874 secs]
[GC 8281K->8135K(9152K), 0.0103799 secs]
[GC 8756K->8722K(9408K), 0.0075765 secs]
[Full GC 8722K->3251K(9408K), 0.3584338 secs]
[GC 3867K->3847K(9152K), 0.0058058 secs]
[GC 4484K->4461K(9152K), 0.0074072 secs]
[GC 5096K->5083K(9152K), 0.0066087 secs]
[GC 5720K->5707K(9152K), 0.0060539 secs]
[GC 6331K->6304K(9152K), 0.0073750 secs]
[GC 6935K->6907K(9152K), 0.0081022 secs]
[GC 7523K->7496K(9152K), 0.0074461 secs]
Regards
SAM

Answer 1

This is a quote from the following article: http://java.sun.com/docs/hotspot/gc/index.html
The command line argument -verbose:gc prints information at every collection. For example, here is output from a large server application:
[GC 325407K->83000K(776768K), 0.2300771 secs]
[GC 325816K->83372K(776768K), 0.2454258 secs]
[Full GC 267628K->83769K(776768K), 1.8479984 secs]
Here we see two minor collections and one major one. The numbers before and after the arrow indicate the combined size of live objects before and after the GC. (After minor collections the count includes objects that aren't necessarily alive but can't be reclaimed, either because they are directly alive, or because they are within or referenced from the old generation.) The number in parenthesis is the total available space, which is the total heap minus one of the survivor spaces.