Java profiler results.

Question

Greetings all ---
I am trying to use the java profiler that comes with the jvm (jdk1.3). Searching the forums, I found the suggestion to run with -Xprof switch. I did that here are my results. Can someone please explain:
I ran my program with this command
java -Xprof findLinkThread
Flat profile of 26.56 secs (2586 total ticks): Keep-Alive-Timer:localhost
Thread-local ticks:
100.0% 2586      Blocked (of total)
Flat profile of 83.34 secs (8077 total ticks): Thread-1
Thread-local ticks:
100.0% 8077      Blocked (of total)
Global summary of 84.84 seconds :
100.0% 8262      Received ticks
0.4% 35      Received GC ticks
0.2% 13     Compilation
0.0% 2 Other VM operations
0.8% 66 Class loader
0.0% 2 Unknown code
what does this mean ? is it good or bad ?
can I get the prepackaged profiler to tell me anything useful in terms of what is slowing things down etc /
stev

Answer 1

All that those results say to me is that garbage collection and class loading doesn't represent much of a hit for your application. I think you were after something a little more like...$ java -version
java version "1.3.0"
Java(TM) 2 Runtime Environment, Standard Edition (build 1.3.0-C)
Java HotSpot(TM) Client VM (build 1.3.0-C, mixed mode)
$java -Xrunhprof:help
Hprof usage: -Xrunhprof[:help]|[<option>=<value>, ...]
Option Name and Value   Description             Default
heap=dump|sites|all     heap profiling          all
cpu=samples|times|old   CPU usage               off
monitor=y|n             monitor contention      n
format=a|b              ascii or binary output  a
file=<file>             write data to file      java.hprof(.txt for ascii)
net=<host>:<port>       send data over a socket write to file
depth=<size>            stack trace depth       4
cutoff=<value>          output cutoff point     0.0001
lineno=y|n              line number in traces?  y
thread=y|n              thread in traces?       n
doe=y|n                 dump on exit?           y
Example: java -Xrunhprof:cpu=samples,file=log.txt,depth=3 FooClass
$java -Xrunhprof:cpu=times,file=prof.txt,depth=10 Shuffle
$cat prof.txt
CPU TIME (ms) BEGIN (total = 180) Mon Nov 19 11:10:57 2001
rank   self  accum   count trace method
   1 11.11% 11.11%       5    14 java.util.jar.Attributes.read
   2  5.56% 16.67%       3     9 java.io.PrintStream.write
   3  5.56% 22.22%       1    10 java.util.Properties.load
   4  5.56% 27.78%      30    17 java.io.PrintStream.write
   5  5.56% 33.33%       1     3 java.security.Security.loadProviders
   6  5.56% 38.89%       5    11 java.io.ByteArrayInputStream.<init>
   7  5.56% 44.44%     831     8 java.util.jar.Attributes$Name.isAlpha
   8  5.56% 50.00%       1     2 java.lang.ClassLoader$NativeLibrary.load
   9  5.56% 55.56%       5     7 sun.misc.URLClassPath$JarLoader.getClassPath
  10  5.56% 61.11%     105     5 java.io.BufferedReader.readLine
  11  5.56% 66.67%       1     6 java.io.Win32FileSystem.getBooleanAttributes
  12  5.56% 72.22%      44    12 java.lang.StringBuffer.expandCapacity
  13  5.56% 77.78%     185    16 java.lang.StringBuffer.append
  14  5.56% 83.33%       1    13 java.lang.ClassLoader.checkCerts
  15  5.56% 88.89%       1    18 java.io.FilePermission.<init>
  16  5.56% 94.44%      30     4 java.io.PrintStream.newLine
  17  5.56% 100.00%     210    15 java.io.Win32FileSystem.isSlashFor example, in the above profile, StringBuffer.expandCapacity takes 5% of the running time, so I might want to create my StringBuffers with higher initial capacity.
BTW- this was running on Windows NT, the runhprof options may be different (or omitted) on other platforms.
Hope this helps,
-Troy