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Posted to users@wicket.apache.org by eaglei22 <jc...@gmail.com> on 2014/02/19 02:23:20 UTC
Issue on multi-threaded page when opening another tab in browser
Okay, so I have an issue that I have finally narrowed down to multi-threading
issues.
I have a loader page that has a worker thread to process a csv file and
store the results into a list declared as:
List batchLines = Collections.synchronizedList(new
CopyOnWriteArrayList<BatchLine>());
Each BatchLine object is a row in the csv file that was processed.
I also have a pageableListView on the page that uses the BatchLine List to
update itself. I use a
AjaxSelfUpdatingTimerBehavior which will update the pageableListView every
two seconds. The problem is, if I am on this page in one browser tab, and
the workerthread is running, and the page is updating, and then at the same
time I open another instance of the application in another tab of the same
browser, the thread loses focus of this List. I know this because I print
out the size of the list, and it stays the same when I open a new instance.
I first had the List batchLines Global, but now I pass it as a parameter to
keep it local to each method. When it was global, I had to mark it transient
for serializable issues. The issue with this is the page would crash when I
opened a new tab with another instance of the application.
What can I do to prevent this?
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Re: Issue on multi-threaded page when opening another tab in
browser
Posted by eaglei22 <jc...@gmail.com>.
Nvm, it's still doing it.
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Re: Issue on multi-threaded page when opening another tab in
browser
Posted by eaglei22 <jc...@gmail.com>.
I fixed this issue by making my runnable class serializable and putting a
reference to the Thread inside there and also the list. This seemed to fix
this issue.
Thanks for your time Martin.
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Re: Issue on multi-threaded page when opening another tab in
browser
Posted by eaglei22 <jc...@gmail.com>.
Hi Martin,
I originally had the List as an instance variable for the Page but when I
would open a new browser tab, the original page would crash and a
nullpointerException would be given because the page reference lost
reference to the object.
So now I create in the page constructor in instance of BatchLines and pass
it along through method parameters.
The thread is started from a method called in the constructor. Here is the
def of this method:
/****************************************************
* Method: beginProcessing
*
* Invokes workerThreads
*
* returns: void
****************************************************/
private void beginProcessing(List batchLines)
{
fullReportDwnLoadBtn.setVisible(false);
try
{
csvFileCreater = new CSVFileCreater(LOADER_CSV_FILE_NAME);
if(turnOnLoader)
{
BatchLoaderProcessingThread threadJob = new
BatchLoaderProcessingThread(stringList, batchLines);
loggerThread = new Thread(threadJob);
loggerThread.start();
}
else
{
BatchDeleteProcessingThread deleterThreadJob = new
BatchDeleteProcessingThread(stringList, batchLines);
loggerThread = new Thread(deleterThreadJob);
loggerThread.start();
}
} catch (IOException e)
{
// TODO Auto-generated catch block
log.error("Inside beginProcessing() throws error: " + e.toString());
BatchProcessPage.this.error("An error has occurred starting creation of
CSV file");
}
}
Here is the definition of the thread class:
class BatchLoaderProcessingThread implements Runnable
{
List stringList;
List batchLines;
public BatchLoaderProcessingThread(List stringList, List batchLines)
{
this.batchLines = batchLines;
this.stringList = stringList;
}
@Override
public void run()
{
processLine(stringList, batchLines);
loaderFinished();
}
}
processLine is a method that is part of the Page class.
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Re: Issue on multi-threaded page when opening another tab in browser
Posted by Martin Grigorov <mg...@apache.org>.
Hi,
On Wed, Feb 19, 2014 at 3:23 AM, eaglei22 <jc...@gmail.com> wrote:
> Okay, so I have an issue that I have finally narrowed down to
> multi-threading
> issues.
>
> I have a loader page that has a worker thread to process a csv file and
> store the results into a list declared as:
>
> List batchLines = Collections.synchronizedList(new
> CopyOnWriteArrayList<BatchLine>());
>
Where is declared this list ?
I.e. who keeps the reference to it ?
Also how do you start the Thread ?
>
> Each BatchLine object is a row in the csv file that was processed.
>
>
> I also have a pageableListView on the page that uses the BatchLine List to
> update itself. I use a
> AjaxSelfUpdatingTimerBehavior which will update the pageableListView every
> two seconds. The problem is, if I am on this page in one browser tab, and
> the workerthread is running, and the page is updating, and then at the same
> time I open another instance of the application in another tab of the same
> browser, the thread loses focus of this List. I know this because I print
> out the size of the list, and it stays the same when I open a new instance.
>
> I first had the List batchLines Global, but now I pass it as a parameter to
> keep it local to each method. When it was global, I had to mark it
> transient
> for serializable issues. The issue with this is the page would crash when I
> opened a new tab with another instance of the application.
>
> What can I do to prevent this?
>
>
>
> --
> View this message in context:
> http://apache-wicket.1842946.n4.nabble.com/Issue-on-multi-threaded-page-when-opening-another-tab-in-browser-tp4664552.html
> Sent from the Users forum mailing list archive at Nabble.com.
>
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> To unsubscribe, e-mail: users-unsubscribe@wicket.apache.org
> For additional commands, e-mail: users-help@wicket.apache.org
>
>