Re: PDF rendering in background blocks other requests

UPD: after spending some time debugging I found the place where it’s
actually blocking.

It’s TapestrySessionFactoryImpl.acquireWriteLock() method and,
specifically, this part:

lock.writeLock().lock();

perthreadManager.addThreadCleanupCallback(new Runnable()
{
    public void run()
    {
        // This is the only way a write lock is unlocked, so no check is needed.
        lock.writeLock().unlock();
    }
});

I’m using servlet filter to perform user session authentication, and
ApplicationStateManager to check the current session.
Now, Tapestry’s SessionImpl is like this:

public Object getAttribute(String name)
{
    lock.acquireWriteLock();

    return session.getAttribute(name);
}

Meaning, when I’m retrieving session attribute at the beginning of the
request, the lock won’t be released until the request is completed and
PerThreadManager cleanup is run.

Is that a known issue? Was it made this way for a reason? (I’m on 5.4-beta6
for several reasons).



On Sun, Mar 18, 2018 at 2:30 PM, Ilya Obshadko <[email protected]> wrote:

> Hi everyone,
>
> I’m struggling to understand the cause of the following issue:
>
> - my Tapestry application generates certain PDF files using Apache FOP and
> Saxon
> - when PDF generator process is started, other requests to that instance
> are blocked until it’s finished
> - moving FOP processing to a new thread using ParallelExecutor.invoke()
> doesn’t seem to affect anything
>
> Any ideas why?
>
> I had a hypothesis that FOP processing actually blocks the whole thing
> because of AWT usage, but couldn’t find any confirmations yet.
>
> --
> Ilya Obshadko
>
>
>
>


-- 
Ilya Obshadko