Re: Get performance statistics?
Robert Klemme wrote:
On 27.11.2006 17:06, Patricia Shanahan wrote:
Robert Klemme wrote:
On 27.11.2006 08:17, Daniel Pitts wrote:
Patricia Shanahan wrote:
I would like to collect, inside a Java application, statistics such as
the amount of CPU time used. Any idea how?
I can, of course, measure the elapsed time, but that does not tell me
how much time was spent actually computing vs. waiting for disk.
Patricia
A quick googling leads me to believe you might need to use JNI (and
therefore have a platform-specific solution)
<http://www.google.com/search?q=java+system+monitoring>
Example for CPU on Win32
<http://www.javaworld.com/javaworld/javaqa/2002-11/01-qa-1108-cpu.html>
JVMTI might also help:
http://java.sun.com/j2se/1.5.0/docs/guide/jvmti/index.html
http://java.sun.com/j2se/1.5.0/docs/guide/jvmti/jvmti.html#timers
A low level solution would be to create a TimedInputStream and
TimedOutputStream which measure and sum up time spend in write() and
read(). You could then substract that from wall clock for this
thread. If you want to get more fancy those streams could register
themselves with some thread global counter so you automatically get
all IO timings if you make sure every stream is replaced (not easy
though with 3rd party libs like JDBC drivers). It depends on what
you actually want to measure and to what level of detail.
JVMTI looks interesting. The disk accesses that I'm worried about are
due to paging, not explicit requests, but JVMTI does have CPU time
collection.
If it is just for a one time debug (i.e. not necessarily part of a
product, I am not 100% sure from what you wrote) you could use OS
specific tools. On Windows that should be fairly easy with PerfMon and
on Linux you can use iostat, vmstat and relatives.
The lack of clarity about debug vs product is inherent in the nature of
the application. It is part of a CS research project. Understanding the
behavior of the program is part of the product.
Yes, there are basically two alternatives. Ideally, I would like the
data to appear in the output file, so that it is packaged with the rest
of the information about the run. However, I may go outside.
Either way, I'm afraid it is going to be less convenient than my current
lifestyle - one makefile to control the runs, one Jar file to contain my
program, and it all works on my home system, works on my university
desktop, and runs dozens of jobs in parallel on a large grid computer.
Patricia