Add time stamp to your GC log file name

To avoid overwriting your gc log once the service restart expected, you had better to add a time stamp to your gc log file, simply as this:

 rem Tested FOR WIN7 OS:  
 rem set time format:  
 set hour=%time:~0,2%  
 if "%hour:~0,1%" == " " set hour=0%hour:~1,1%  
 set min=%time:~3,2%  
 if "%min:~0,1%" == " " set min=0%min:~1,1%  
 set secs=%time:~6,2%  
 if "%secs:~0,1%" == " " set secs=0%secs:~1,1%  
 rem set date format:  
 set year=%date:~-8,4%  
 set month=%date:~0,2%  
 if "%month:~0,1%" == " " set month=0%month:~1,1%  
 set day=%date:~3,2%  
 if "%day:~0,1%" == " " set day=0%day:~1,1%  
 set datetime=%year%%month%%day%_%hour%%min%%secs%  
 set GCLOG=-XX:+PrintGCDetails -XX:+PrintGCDateStamps -Xloggc:gc-%datetime%.log  

The output like this: gc-20120507_172101.log
Notice: "-XX:+PrintGCDateStamps" option is only available for JDK6u4+, otherwise, you need add "-XX:+PrintGCTimeStamps" instead. Never leave any space at the end of line in your batch script, it will trigger stupid result...