Make ComponentRenderer implement AutoCloseable?

[Thorsten Schöning <ts...@am-soft.de>]

Hi all,

I'm using Wicket as a template engine to render reports in some
backend with various different output formats. Everything is based on
"ComponentRenderer", though, and that introduced a large memory leak
in my case. Root cause simply was that I forgot to call "destroy".

So how about implementing AutoCloseable by that class? In most IDEs
that would have at least triggered a warning.

Mit freundlichen Grüßen,

Thorsten Schöning

-- 
Thorsten Schöning       E-Mail: Thorsten.Schoening@AM-SoFT.de
AM-SoFT IT-Systeme      http://www.AM-SoFT.de/

Telefon...........05151-  9468- 55
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Re: Make ComponentRenderer implement AutoCloseable?

[Thorsten Schöning <ts...@am-soft.de>]

Guten Tag Sven Meier,
am Sonntag, 24. Mai 2020 um 23:18 schrieben Sie:

> ComponentRender#destroy() destroys the application, there's not much
> more to it.

That's the important part, because otherwise one gets a memory leak
when having multiple applications, because they are stored in
"Application.applicationKeyToApplication".

> So auto-closing i.e. destroying the renderer after each render might
> lead people into the wrong direction.

Then the following sentence in the docs should make more clear that if
to call "destroy" or not depends on the lifecycle of the app, not the
renderer:

> Note: For performance reasons instances can and should be reused, be
> sure to call {@link #destroy()} when they are no longer needed.

This reads like it depends on the instances of the renderer to me, but
then one couldn't reuse apps at all, because they are always destroyed.

How do I destroy an application without "ComponentRenderer#destroy",
when the app really should be reused by multiple renderers? 

I only see "Application.internalDestroy", which explicitly warns me to
not use it. "ComponentRenderer.destroy" looked like the only official
way to cleanup to me.

Mit freundlichen Grüßen,

Thorsten Schöning

-- 
Thorsten Schöning       E-Mail: Thorsten.Schoening@AM-SoFT.de
AM-SoFT IT-Systeme      http://www.AM-SoFT.de/

Telefon...........05151-  9468- 55
Fax...............05151-  9468- 88
Mobil..............0178-8 9468- 04

AM-SoFT GmbH IT-Systeme, Brandenburger Str. 7c, 31789 Hameln
AG Hannover HRB 207 694 - Geschäftsführer: Andreas Muchow

Re: Make ComponentRenderer implement AutoCloseable?

[Sven Meier <sv...@meiers.net>]

Hi Thorsten,

ComponentRender#destroy() destroys the application, there's not much 
more to it.

In most cases you will want to reuse the application for performance 
reasons. A specific application can even be used as constructor 
argument, which might be the main web application that you don't want to 
be destroyed prematurely.

So auto-closing i.e. destroying the renderer after each render might 
lead people into the wrong direction.

Have fun
Sven


On 24.05.20 16:28, Thorsten Schöning wrote:
> Hi all,
>
> I'm using Wicket as a template engine to render reports in some
> backend with various different output formats. Everything is based on
> "ComponentRenderer", though, and that introduced a large memory leak
> in my case. Root cause simply was that I forgot to call "destroy".
>
> So how about implementing AutoCloseable by that class? In most IDEs
> that would have at least triggered a warning.
>
> Mit freundlichen Grüßen,
>
> Thorsten Schöning
>