Setting a limit is "Plan B". You are correct re. the paging needing to
be done at the db level--will do that in the next release.
On 10/24/2011 12:41 PM, Jasha Joachimsthal wrote:
On 24 October 2011 18:29, Paul Joseph <[email protected]
<mailto:[email protected]>> wrote:
Actually the real reason is that the user is using a query that
required crafting to return 25K results. He is seeking to show
the system "does not scale."
Then set a limit when building the query
Actually I am using in my XML template, a cocoon flowscript
repeater widget that does paging. But this is well after the Java
logic has built the large array of results (the array results and
the vector secureResults below)
The actual paging should be done on DB level, not after you've fetched
the enormous amount of results.
On 10/24/2011 12:22 PM, Jasha Joachimsthal wrote:
The first question that comes to my mind: why would you need
25000 objects as query result? Can't you do 1 query that only
returns the total possible amount of objects and another query
that returns e.g. the first 10 results and build in some paging
logic for the next 10.
Jasha Joachimsthal
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522 4466 <tel:%2B31%280%2920%20522%204466>
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On 24 October 2011 18:13, Paul Joseph <[email protected]
<mailto:[email protected]>> wrote:
I think you hit the nail on the head.
I assumed that the memory is freed at session time out. I did
not realize this was not the case.
I know what the culprit is in this case--the array that I use
to store the objects returned from the query.
I do this in two places--once in the business logic (java
code) and once in the flow script.
The code in the java business logic is as follows--the item
of interest is a "Task". How would I optimize it in terms of
memory collection?
public Object[] getSearchResults() throws Exception {
Object[] results = getSearchResultBeans(sql_query);
Vector secureResults = new Vector();
for (int n=0; n < results.length; n++) {
Task t = (Task)results[n];
if (securityManager.canIViewTask(t))
secureResults.add(t);
}
return secureResults.toArray();
}
On 10/24/2011 11:50 AM, Nathaniel, Alfred wrote:
Hi Paul,
I don't think that it is a database issue.
It is rather the question where the application places
the large amounts of data and how it is cleaned up.
I interprete your statements that it is placed in the
session object assuming that the memory is freed at
session timeout.
Unfortunately that is not the case.
The session timeout is a security feature to force a new
login if the same user comes back after a longish idle time.
There is no guarantee that the container will actually
delete the session object at the session timeout.
As long as there is a reference to the session object GC
cannot free the attached memory.
You will have to find a way that the application keeps
the data only for the duration of a request, or use
another mechanism to limit the memory requirements.
HTH, Alfred.
-----Original Message-----
From: Paul Joseph [mailto:[email protected]
<mailto:[email protected]>]
Sent: Montag, 24. Oktober 2011 17:16
To: [email protected] <mailto:[email protected]>
Subject: thought I had fixe it
Hi there,
I thought I had fixed this memory issue but...
I am using Tomcat 6 in a Windows 32 bit environment
(Windows 2003) with
Cocoon 2.1.11 and Java 1.6, agains Postgresql 8.4 with
the latest
Postgres 9.1, JDBC 4 driver.
The behavior is this:
The user fires of a LARGE query that returns 25,000 large
objects.
The user repeats this 20 times within 5 minutes to show
me he can freeze
the app.
On the 20th time, it says out of memory (heap space).
The JVM indicates that it is maxed to the limit specified
in Xms and
that there is only about 2MB of memory free.
I then ask her to log off.
The session time out is set to 20 minutes.
But even after an hour, the memory is not reclaimed by
the JVM--it still
reports that only about 2MB is still free.
Is the fact that it is not reclaiming memory an
indication of a memory leak?
I am using the following settings in my repository.database:
<jdbc-connection-descriptor
jcd-alias="WebApp"
default-connection="true"
platform="PostgreSQL"
jdbc-level="4.0"
driver="org.postgresql.Driver"
protocol="jdbc"
subprotocol="postgresql"
dbalias="//localhost:5432/WebApp"
username="******"
password="******"
eager-release="false"
batch-mode="false">
<connection-pool maxActive="200" validationQuery="" />
<sequence-manager
className="org.apache.ojb.broker.util.sequence.SequenceManagerNextValImpl"
/>
</jdbc-connection-descriptor>
Thanks much!
Paul
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