Per-thread scope means to create a new implementation, via the builder
method, once for every request: buldUserCacheSupport() is invoked the first
time any method of UserCacheSupport is invoked.
EnvironmentalBuilder creates a proxy class and instance, and is intended to
only be invoked once per service; that is, a singleton service. Since it
is being invoked multiple times, it is creating one proxy class after
another, and these are accumulating in PermGen.
There is no need to make UserCacheSupport per-thread, since everything in
the Environment is already per-thread.
On Fri, Nov 30, 2012 at 9:48 AM, Christian Riedel
<cr.ml...@googlemail.com>wrote:
> Hi everone,
>
> today I found the reason for a recent memory leak and I thought I'd ask
> what you think of it:
>
> Rather by accident I annotated one of the
> EnvironmentalShadowBuilder-methods with @Scope(PERTHREAD)
>
> @Scope(ScopeConstants.PERTHREAD)
> public UserCacheSupport buildUserCacheSupport() {
>
> return environmentalBuilder.build(UserCacheSupport.class);
> }
>
> (UserCacheSupport is just a custom environmental)
>
> So I removed the annotation and everything is ok again.
>
> But: Isn't that strange? Is that a known behavior? Using jhat I found
> thousands of undead UserCacheSupport classes tied to a PlasticClassLoader.
> So Plastic creates one class per request (i.e. per thread) and.. somehow
> keeps it. Without the explicit @Scope setting there should also be one new
> object per thread, but it does not cause a leak (since there's not a new
> class for each request, I guess). I'm wondering if it's actually a bug in
> Tapestry?
>
> Cheers
> Christian
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