[ILUG] Retrieve memory used of java process on HP-UX

[Brian Foster]

  | Date: Mon, 29 May 2006 17:50:04 +0200
  | From: "Mark Clifford" <markcliff at gmail.com>
  | 
  | I wanna [ print ] the memory used from a java process
  | using a shell script.
  | 
  | Now i thought i could use the following:
  |   ps -uusername -o vsz, comm | grep java
  | 
  | Which returns:
  |   182332 java
  | 
  | it seems to just return a size that is not the same as
  | the one if i do a top command.  Why is this[? ... ]

 different commands compute "the amount of memory used"
 differently.  the hard part of the computation is what
 to do about memory that is, or could be, shared (used)
 by multiple processes, such as text (code) and shared
 memory (nominally data, i.e. shmat(2) et al.).

 one method is to simply add it all up.  the problem
 here is the value is "too large" when there there are
 many sharers.

 another is to divide the total for shared regions by
 the number of sharers.  the problem here is the value
 will fluxuate up-and-down as processes start/exit.

 a weighted average is therefore sometimes used.  the
 value will still fluxuate, but "slower", and it is
 rather more obscure how the value relates to anything.
 also, there are different weighing algorithms and time
 intervals, increasing the number of different values
 printed.

 and so on ....

 I would suggest either picking a number you believe in,
 which probably means one adequate for yer purpose, or
 defining yer own algorithm, or reworking the issue so
 that you don't need this hard-to-define number.  (or
 use static binaries, where there is less of an issue.)

cheers!
	-blf-
-- 
Experienced (20+ yrs) kernel/software Eng: | Brian Foster   Montpellier,
 • Unix, embedded, &tc;  • Linux;  • doc;  | blf at utvinternet.ie   FRANCE
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