Re: WO and Memory Management
Re: WO and Memory Management
- Subject: Re: WO and Memory Management
- From: Chuck Hill <email@hidden>
- Date: Thu, 13 Jul 2006 20:49:20 -0700
Hi Owen,
On Jul 13, 2006, at 7:33 PM, Owen McKerrow wrote:
Thanks for the response Chuck. See comments below....
On 14/07/2006, at 11:53 AM, Chuck Hill wrote:
On Jul 13, 2006, at 6:15 PM, Owen McKerrow wrote:
Hi All,
We are setting up an application of ours on a clients server,
they did some stress testing to see if they needed a bigger box
and discovered something strange.
Their comments ....
The webobjects versions have been stress tested further, we are
getting ok
results but far worse then I was hoping. RIS Public faired worse
the RIS
with it starting to get error with only 5 simultaneous users
making simple
request 5 seconds apart (running with 2 instances each with -
mx512M.
That is odd. Are you dispatching requests concurrently?
No, getting them to retest with it on.
That should make a considerable difference, unless the app is doing a
lot of EOF activity.
A major point of interest is that garbage collection does not
appear to be
active for these instances.
Check for I/O and DB usage. How long does the average request
take to process?
From the stats page :
Transactions 691
Active Session 0
Average transactions 5.031
Averegae idle 131.627
Five seconds on average is, IMHO, way too long. Either all of your
actions are a little slow or some are very slow. Sight unseen, my
money is on the latter. Usually this is the result of DB access,
either queries that are slow to evaluate due to missing indexes or
lots of single row queries due to a lack of batch faulting and pre-
fetching in the application.
Are you a Project Wonder user? There is a class in there that will
log out all queries that take longer than X seconds to return. That
is a good way of finding slow queries. If not, I can dig out a
similar class. I thought it was in Practical WebObjects, but I can't
find it now. For lots of single queries, the best way I have found
is to just turn on SQL logging and look at what is spit out. If you
see reams of queries one after the other, each returning a single
row, that is your problem.
I will also suggest that you add this to Application or modify what
is there:
/**
* Overidden to log RR loop and gather statistics.
*/
public WOResponse dispatchRequest(WORequest request) {
NSLog.out.appendln("=========== New Request: " + request.uri
());
NSLog.out.appendln("Headers: " + request.headers());
long startTime = System.currentTimeMillis();
WOResponse response = super.dispatchRequest(request);
long endTime = System.currentTimeMillis();
NSLog.out.appendln("Elapsed Time," + (endTime - startTime) /
1000.0 + "," + request.uri());
NSLog.out.appendln("=========== End Request: " + request.uri
());
return response;
}
That will show you the time for each request. You can turn this into
a CSV file for Excel by grepping the log
grep Elapsed AppLog.log > elapsed.csv
That lets you sort by elapsed time to find the max and min and to
graph against time.
We ran the tests yesterday and the started to
consume over 500M per instance (2 instance running for RIS and
RISPublic).
This morning after no activity all night the process are still
using the
full memory set. To me this is a bit of a concern, can you guys
check your
side to see if it the same there, or if there is some
configuration options
that can be put in place to improve this?
The strange thing here is that the instances don't seem to be
releasing memory. Is this normal ? Is there a setting I need to
tweak somewhere in JavaMonitor ?
This is normal for the JVM on OS X. Once the JVM has allocated
memory, it does not return it to the OS until it terminates. You
can have the instances restart more often to return this memory to
the OS. 500M seems like a lot, but that depends on what the app
is doing.
Sorry forgot to mention its on a Solaris Machine running Vs 9. WO
5.2.4 ( witha 5.3 build if it makes any difference ).
IIRC, Solaris is the same in this respect. But the last time I
deployed on Solaris was with Java 1.2 so it has been a few years. :-)
Does you app deal with a large amount of data that might explain this
memory footprint?
Chuck
--
Coming sometime... - an introduction to web applications using
WebObjects and Xcode http://www.global-village.net/wointro
Practical WebObjects - for developers who want to increase their
overall knowledge of WebObjects or who are trying to solve specific
problems. http://www.global-village.net/products/practical_webobjects
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