[infinispan-dev] SKIP_CACHE_LOAD and write skew check

[Sanne Grinovero]

I'm not sure why this specific Flag behaves like this, but it's clear
that Flags can break many things; I suspect originally they were meant
to be internal-only, and I got them exposed when as a user I was
having big performance trouble when doing Put operations of 1GB each
and the damn thing would load the previous value from the MySQL backed
Cachestore, while my puts didn't use the return value :)

Maybe it's time to reconsider this and split the flags up in "internal
ones" and public API flags? It would be nice to limit the damage that
end users can do, many flags could be taken away, or reshape our APIs
to not really need so many (for example not having the put method
return a value, or automating such optimisations with internal magic).

+1 to perform the WSC only on the primary owner, that seems like a severe bug?


On 30 August 2016 at 08:30, Radim Vansa <rvansa at redhat.com> wrote:
> I've noticed that SKIP_CACHE_LOAD flag is ignored when performing the
> write skew check (the old entry is loaded from cache store), though, it
> is not ignored (and the entry is not loaded) when there's
> CACHE_MODE_LOCAL [2]. Is that intended behaviour, or just "conserved" by
> tests?
>
> The flag itself allows to break things [3], so I guess that user sets
> the flag only when he knows that there is no such entry in cache store
> and it's safe to not load it.
>
> Moreover, I don't understand why the WSC should be performed on
> originator (or backup owners) [4].
>
> Thanks for explanations (I'll try to add them as comments to the code -
> or make the reasoning more obvious).
>
> Radim
>
> [1]
> https://github.com/infinispan/infinispan/blob/master/core/src/test/java/org/infinispan/api/flags/FlagsEnabledTest.java#L132
> [2]
> https://github.com/infinispan/infinispan/blob/master/core/src/test/java/org/infinispan/api/flags/FlagsEnabledTest.java#L96
> [3]
> https://github.com/infinispan/infinispan/blob/master/core/src/main/java/org/infinispan/context/Flag.java#L89
> [4]
> https://github.com/infinispan/infinispan/blob/master/core/src/test/java/org/infinispan/api/flags/FlagsEnabledTest.java#L85
>
>
> --
> Radim Vansa <rvansa at redhat.com>
> JBoss Performance Team
>
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