Michael,
Thanks for responding so fast (I appreciate it).
1. The box is shared but the Tomcat server is dedicated to my project
only.
2. The box is 64 bits (Linux 2.6.25-14.fc9.x86_64 (amd64))
3. They have three plans available: 64MB, 128MB, and 256MB
Since we only have one - two users right now I selected 64MB until it
goes live. But based on the recommendations today, we are immediately
upgrading to 128MB.
FYI: I have only about 500 products (and am anticipating 5000
products). I do not use any BLOB's in the database (we only use file
system references to pictures and audio). So I am very concerned that
I missed something fundamental (if you are able to handle 10,000
objects easily).
Questions:
1. The WebHost POC asked me to ask you for a recommendation for Xmx.
2. In the event I made a programming error: please let me know how to
properly release the memory from a result set (ArrayList) in this
scenario. I am a tad confused with the BaseContext management and
could have made a mistake there.
Thanks,
Joe
PS other than this Memory Management issue Cayenne 3M6 has been rock-
solid!!
On Sep 16, 2009, at 2:57 PM, Michael Gentry wrote:
Is your hosting company giving you a private dedicated box (or VM) or
is your application shared with other applications running in Tomcat?
If the latter, that would skew things, I think. Also, if you are
running a 64-bit JVM, then it'll use more memory. It won't be 2x
more, but it'll be more.
In your Cayenne Model, under the DataDomain, what is the size of your
object cache?
On Wed, Sep 16, 2009 at 2:49 PM, Joe Baldwin
<[email protected]> wrote:
Caveat: Apparently I am not as well. :)
1.) I looked at the 65M issue. On my development box (OSX) I set
it to
-Xms128m -Xmx128m (basically arbitrary). So when I went to the
remote
hosting company, I purchase a similar amount.
a. However, we are doing *very* little work (lots of product
fetches
and only a few product inserts and updates) and it runs out of
memory *very*
fast which I *assume* means it is my code, but I don't know.
b. I am doing research and here is a "web
recommendation" (for all
that is worth)
Whenever possible, Unidata recommends
-Xmx1500m for 32-bit systems, and -Xmx2048m --Xmx4096m for
64-bit
systems.
c. Since the host is 64-bit, I am wondering whether my
assumptions
may be off for 64-bit systems.
2. DataContext: Sorry, but I am getting confused on this one. I am
using
BaseContext.getThreadObjectContext() based on recommendations (I
converted
all the old DataContext refs to BaseContext, but I don't really
understand
it from reading the docs) and am *not* releasing it at the end of
session.
Not quite sure of how to do this properly.
3. Don't know how to set the cache to retain N number of objects. I
experimented with
query.setPageSize(RowsPerPage);
query.setCacheStrategy(QueryCacheStrategy.SHARED_CACHE);
query.setCacheGroups("product", "ProductList");
This seemed to help quite a bit but I still eventually ran out of
memory. I
recently removed *all* the SHARED_CACHE and it ran out of memory
very fast.
Thanks for your input
Joe
On Sep 16, 2009, at 2:25 PM, Mike Kienenberger wrote:
Caveat: I'm not really an expert on Cayenne memory management.
1) Are you allocating enough heap memory to the app server to start
with? I don't know what the default is these days, but in the old
days, an application by default only gets 64Mb of memory -- that's
pretty small.
2) Are you using a new DataContext per request? Or at least per
session?
3) I seem to remember that the cache strategy is configurable. Have
you configured a cache that only retains N number of objects for a
suitable value of N?
On Wed, Sep 16, 2009 at 2:11 PM, Joe Baldwin <[email protected]
>
wrote:
Hi,
I have asked this question a number of ways but I still have a very
serious
problem with Cayenne-specific memory management configuration
associated
with Tomcat.
The problem with debugging is that given that I have very little
visibility
into the Cayenne memory management it is extremely difficult to
debug
this
using conventional strategies. Also I am not requesting anything
from
the
system that is terribly exceptional so I am attempting to use
default
settings as much as possible.
My strategy is to ask the experts for a Cayenne configuration and
standard
memory management steps I should take to conform to the new Cayenne
memory
management design intentions.
Problem:
1. I have essentially a webstore, three tier design with Tomcat,
Cayenne
and
MySQL.
2. When after only a few queries of products, tomcat freezes up and
reports
out of memory errors.
I have attempted to configure the caching strategy ask best as I
can
understand from the docks but this only gets me a few more hours
of usage
before the out of memory errors. (I tried the SHARED_CACHE). The
NO_CACHE
strategy is worse.
I would appreciate a set of steps (aka a primer) that should
handle a
website with a lot of fetches of hundreds of data objects (i.e.
products)
and very few updates.
Note: My gut feeling is that I am not properly managing the data
object
array properly and it is leaking memory.
I would appreciate any input, but I would first like to know what
the
minimum require steps are for managing at data object result set
ArrayList
so as to properly cache and then properly free the memory after
it is no
longer needed.
Context: Tomcat, MySQL, Cayenne 3.0M6
Thanks,
Joe Baldwin
