Hmmm... would it be horrible if the return value of handleRow() was a
boolean for "continue"?
// don't mind the verbosity or any misplaced
// capital letters...thank you outlook
public boolean handleRow (Object valueObject) {
boolean continue = true;
if (someCondition) {
continue = false;
}
return continue;
}
I hate to suggest making use of the return value, because there is only
one...but it isn't used right now. Is this the best use of the return
value? The alternative is to use a second parameter for controls...
public void handleRow (ResultSetControl control, Object valueObject) {
if (someCondition) {
control.setContinue(false);
}
}
Sorry if this has already been discussed, it's more of a dev@ issue, but
since we're talking about it here...
Thoughts?
Clinton
-----Original Message-----
From: Harvey Kim [mailto:[EMAIL PROTECTED]
Sent: January-30-08 11:51 AM
To: ibatis user
Subject: Re: Exit out of rowHandler
Here is the code that is causing the memory leak:
sqlMapClient.queryWithRowHandler("getSomeList", queryObject, this);
public void handleRow (Object valueObject)
{
;
}
As you can see, I do nothing except issue the query. my "handleRow" is
empty and it eventually runs out of memory.
Now, here is how I found out about the memory problem - as the number of
rows started to increase, the available memory started going down.
public void handleRow (Object valueObject)
{
try
{
Runtime r = Runtime.getRuntime();
if (rowCount++ % 10000 == 0)
{
System.out.println("***********************************************
" + rowCount);
System.out.println("free memory is: " + r.totalMemory() + " : "
+ r.freeMemory());
//r.gc();
//System.out.println("free memory is: " + r.totalMemory() + " :
" + r.freeMemory());
}
}
catch (Exception e)
{
logger.error("DownloadAction: handleRow ", e);
}
}
I understand your position but if all I'm doing is issuing the query and
my handleRow method does absolutely nothing - AND using JDBC goes
through without a memory problem - I honestly don't know where else to
look because I don't have any other code to look at. It's simply ibatis
and a "handleRow" call.
Here is my JDBC equivalent. Essentially same as above.
Context context = new InitialContext();
DataSource dataSource = (DataSource) context.lookup("jdbc/XXXXX");
Connection connection = dataSource.getConnection();
PreparedStatement preparedStatement =
connection.prepareStatement(sqlString);
ResultSet resultSet = preparedStatement.executeQuery();
while (resultSet.next())
{
/* java stuff */
}
On Wed, 30 Jan 2008 11:36:05 -0700, "Nathan Maves"
<[EMAIL PROTECTED]> said:
> I too have used RH'ers over very large data sets and never saw any memory
> issues. Be careful when issuing statements like "And there is absolutely
> no
> doubt that the culprit is ibatis". I can't tell you how many times we
> have
> seen claim of ibatis failures only to find our that it was not.
>
> Give us some actual code and test cases that cause this issue.
>
> Nathan
>
> On Jan 30, 2008 11:05 AM, Harvey Kim <[EMAIL PROTECTED]> wrote:
>
> > You are absolutely right - I can let it ride it out. And I would agree
> > with you if the query came back within a second or two. But million
> > rows don't come back that quickly and the user will want to continue
> > with other operation after they cancel. Unfortunately, all buttons are
> > disabled during the download so I need to detect when the download is
> > finished to re-enable them. Otherwise, the user will have to wait.
> > Unfortunately, one of the first operation that QA did during the
> > download was "cancel" :). Just my luck ...
> >
> > Anyway, sqlMap.endConnection() forces handleRow to throw an Exception
> > which ends the "handleRow" processing. At that point, my javascript via
> > an Ajax call can detect the "cancel" and re-enable the necessary
> > buttons. And I agree with you, I don't want to forcibly disconnect
> > ibatis connection but only other option I see is to put in the user's
> > manual that if they cancel a download, they'll need to wait a minute or
> > two before they can continue.
> >
> > But this whole thing maybe moot. If the memory leak problem is not
> > resolved, I may have to resort to JDBC. Than I can end the loop at my
> > discretion :).
> >
> >
> >
> > On Wed, 30 Jan 2008 10:34:06 -0700, "Christopher Lamey"
> > <[EMAIL PROTECTED]> said:
> > > Interesting - I don't think I used a groupBy with my large volume
> > > RowHandlers.
> > >
> > > If you're writing to the output stream from the RowHandler and the
user
> > > Cancels the download, wouldn't the stream get closed and cause an
> > > exception
> > > the next time you tried to write?
> > >
> > > It seems like you're going through a lot of ugly work to handle the
> > > 'Cancel'
> > > action - is it absolutely necessary? Worst case is you have a Thread
> > > spinning through the millions of rows for no reason because the user
> > said
> > > 'No' halfway through the operation. How often is that expected to
> > > happen?
> > > How many users do you have that are expected to do the download? How
> > > loaded
> > > up is your application that having a Thread finish the processing
would
> > > be
> > > noticeable and cause a problem?
> > >
> > > Maybe you could have something like this:
> > >
> > > private boolean noop = false;
> > >
> > > public void handleRow (Object valueObject)
> > > throws SQLException {
> > >
> > > if (noop) {
> > > // if first time to hit this, do any cleanup here
> > > return;
> > > }
> > >
> > > // Rest of your code
> > > }
> > >
> > > public void setNoop(boolean b) {
> > > this.noop = b;
> > > }
> > >
> > > When you detect the Cancel operation you call 'setNoop(true)' on the
> > > RowHandler and it just spins through the rest of the records. That
> > > Thread
> > > would then be busy running through the rest of the results, but might
be
> > > ok
> > > since no user is waiting on it.
> > >
> > > Generally I tend to think that any time you find yourself messing
around
> > > with the connections iBATIS is using, you're doing something wrong.
> > >
> > >
> > > On 1/30/08 10:18 AM, "Harvey Kim" <[EMAIL PROTECTED]> wrote:
> > >
> > > > Thanks - that's good to know. That gives me a warm fuzzy feeling.
> > > >
> > > > I guess the issue now is to figure out what type of query in ibatis
is
> > > > causing the memory leak. And there is absolutely no doubt that the
> > > > culprit is ibatis. JDBC with the same query left no residue of
memory
> > > > leaks. And rearranging the query by eliminating the groupBy clause
in
> > > > the ibatis xml file eliminated 90% of the memory leak. Also,
straight
> > > > forward query from one table that returns millions of rows from
ibatis
> > > > yielded NO memory leaks. So there's something about joins but more
> > > > significantly - group by clause. My guess is that ibatis must be
> > using
> > > > some sort of a Map to implement the groupBy clause and is simply
> > letting
> > > > it grow indefinitely.
> > > >
> > > > One more bit of information. Just throwing an Exception alone in
the
> > > > "handleRow" will not get you out of the "loop". I had to issue
> > > > "sqlMap.endConnection()" to force the calling routine within ibatis
to
> > > > throw a NullPtrException in order to exit. If anybody has any other
> > > > ideas, I'd appreciate it. It does work but it's very ugly.
> > > >
> > > > On Tue, 29 Jan 2008 20:24:13 -0700, "Chris Lamey"
> > > > <[EMAIL PROTECTED]> said:
> > > >> I have processed millions of rows with a rowhandler and no memory
> > leaks
> > > >> in several different applications.
> > > >>
> > > >>
> > > >> -----Original Message-----
> > > >> From: Harvey Kim [mailto:[EMAIL PROTECTED]
> > > >> Sent: Tue 1/29/2008 5:23 PM
> > > >> To: ibatis user
> > > >> Subject: Re: Exit out of rowHandler
> > > >>
> > > >> Thanks, I'm currently throwing an exception but that is really
ugly.
> > I
> > > >> was hoping for more "graceful" solution. But I guess I can live
with
> > > >> it. Oh, and "Cancel" button won't be a problem - I got that
covered.
> > > >>
> > > >> Another thing - I've issued this question few months back but there
> > ws
> > > >> no reply. Does anybody know anything about memory leak problem
when
> > > >> using the RowHandler? After processing about 200,000 rows or so, I
> > > >> noticed that "available memory" starts to decrease. This is more
> > > >> prevalent when using a "groupBy" clause. When I took out the
groupBy
> > > >> clause, memory leak appeared to go have gone away but it slowly
> > started
> > > >> appearing at 200,000th row (give or take few thousands).
> > > >>
> > > >> Just for kicks, I converted everything to JDBC with exactly the
same
> > > >> code and it successfully processed 1 million rows with absolutely
no
> > > >> memory leaks. Meaning, instead of calling ibatis with RH, I simply
> > put
> > > >> it in a loop after issuing the same SQL generated by ibatis via
JDBC.
> > > >> Meaning, my code was exactly the same except instead of being
inside
> > the
> > > >> "handleRow", it was inside the loop. With this evidence, I became
> > > >> suspicious of the ibatis RH.
> > > >>
> > > >> I guess what I'm asking is if anybody ever successfully processed
> > > >> millions of row using RH without a memory leak . I'd hate to
resort
> > > >> back to JDBC when ibatis makes everything so much easier.
> > > >>
> > > >> I'd appreciate any input,
> > > >>
> > > >> thanks,
> > > >>
> > > >> -Harvey
> > > >>
> > > >>
> > > >> On Tue, 29 Jan 2008 16:52:02 -0700, "Larry Meadors"
> > > >> <[EMAIL PROTECTED]> said:
> > > >>> On Jan 29, 2008 4:34 PM, Harvey Kim <[EMAIL PROTECTED]> wrote:
> > > >>>> Anybody know how to gracefully exit out of "handleRow" method?
> > Before
> > > >>>> anybody suggests using "queryFor*" methods, I need to be able to
> > query
> > > >>>> for potentially 12 million rows. It's a straight download to an
> > excel
> > > >>>> file so nothing is being displayed (thank god). Anyway, I'm
trying
> > to
> > > >>>> exit out of "handleRow" method when the user clicks on the
"cancel"
> > > >>>> button from the standard download dialogue box.
> > > >>>
> > > >>> Hm, red flag there - I assume you're talking web app, but I don't
> > > >>> think the request is canceled when the user clicks on the cancel
> > > >>> button, it'll still going to run.
> > > >>>
> > > >>> In any case, the only current way to cancel RH processing is to
> > throw
> > > >>> an exception from the handleRow method. Not sexy, but it works.
:-)
> > > >>>
> > > >>> Larry
> > > >>
> > > >> --
> > > >> http://www.fastmail.fm - Email service worth paying for. Try it for
> > free
> > > >>
> > > >>
> > >
> >
> > --
> > http://www.fastmail.fm - Access all of your messages and folders
> > wherever you are
> >
> >
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