Re: Large Array Clogging
Re: Large Array Clogging
- Subject: Re: Large Array Clogging
- From: Drew Thoeni <email@hidden>
- Date: Wed, 9 Jan 2008 18:04:54 -0500
James,
Implemented this yesterday and it works as advertised, that is,
perfectly. I can calculate all the stats for the 18,000 parents and
100,000,000 children in an hour too! Thanks for the pattern.
Best,
Drew
On Jan 6, 2008, at 5:55 PM, James C. Lee wrote:
I should clarify that there are separate editing contexts for the
parents
and children:
public void foo() {
NSArray parents;
NSArray children;
Enumeration anEnum;
EOEditingContext ecParent, ecChildren;
ecParent = new EOEditingContext();
// fetch parents with ecParent...
anEnum = parents.objectEnumerator();
while (anEnum.hasMoreElements()) {
aParent = (Parent)anEnum.nextElement();
ecChildren= new EOEditingContext();
children = fetch_with_editingContext(ecChildren);
// processing...
children = null;
ecChildren();
ecChildren= null;
System.gc();
}
}
^James
-----Original Message-----
From:
webobjects-dev-bounces+jcl_applewodev=email@hidden
ple.com
[mailto:webobjects-dev-bounces+jcl_applewodev=dreamissary.com@
lists.apple.com] On Behalf Of James C. Lee
Sent: Sunday, January 06, 2008 2:46 PM
To: 'WebObjects-Dev List'
Subject: RE: Large Array Clogging
Drew,
Try this:
public void foo() {
NSArray parents;
NSArray children;
Enumeration anEnum;
EOEditingContext editingContext;
// fetch parents
anEnum = parents.objectEnumerator();
while (anEnum.hasMoreElements()) {
aParent = (Parent)anEnum.nextElement();
editingContext = new EOEditingContext();
children = fetch_with_editingContext(editingContext);
// processing...
children = null;
editingContext.dispose();
editingContext = null;
System.gc();
}
}
^James
-----Original Message-----
From:
webobjects-dev-bounces+jcl_applewodev=email@hidden
ple.com
[mailto:webobjects-dev-bounces+jcl_applewodev=dreamissary.com@
lists.apple.com] On Behalf Of Chuck Hill
Sent: Sunday, January 06, 2008 1:57 PM
To: Drew Thoeni
Cc: WebObjects-Dev List
Subject: Re: Large Array Clogging
On Jan 6, 2008, at 11:53 AM, Drew Thoeni wrote:
I have two tables in a parent-child relationship. Some of the
parents have a few children (say a few dozen) and others have many
children (over 100,000). I'm trying to run through the
parents and
pre-calculate some statistics for their children (for example,
average, mode, standard deviation, etc.).
I'd be tempted to take a long, hard look at some of the aggregate
functions in Wonder that generate SQL for you. Batch
processing is
not EOF's strongest area due to the overhead of object
creation and
garbage collection.
All this is working except when I reach a specific parent
(#457) the
processing just hangs. I ran this through debug and it stalls
at the creation of the array for the children.
However, the system would have already processed a similar size
array (#30 has 118,000 children) and it seems it's in a loop.
Activity monitor says the java process is taking 100%.
Other background. I only save the ec after every 20
updates to the
parent records (to reduce write time). And I use
ec.invalidateAllObjects() right after saving to clear our memory.
Rather than do that, I'd create a new EC and just not retain _any_
references to the objects previously processed, the previous
EC etc.
EOF snapshot counting and Java GC should take care of the rest.
Finally, there is nothing wrong with the data in
parent/children of
#457 as I can start the process there (or a few parents ahead of
this) and it runs fine.
This seems like a memory problem, but I don't get an out
of memory
exception.
Before OutOfMemory, there is memory starvation. I think that
is what
is happening to you. Increase the heap size and see if
that delays
the problem to a later parent. You could also launch with a JVM
parameter of -verbose:gc to log when GC happens.
The solution is to clean up your handling of objects and editing
contexts.
Chuck
--
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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