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From Aaron McCurry <>
Subject Re: enable/disable bug, caching, and stuff
Date Tue, 12 Aug 2014 17:56:31 GMT
On Tue, Aug 12, 2014 at 1:21 PM, Tim Williams <> wrote:

> We have a bug where you disable the table and it doesn't show as
> disabled - I suspect the other way is problematic too but don't know
> for sure.  Looking into this brings up a few questions:
> 1) Based on the usage, I'm not so sure the tableDescriptor even needs
> to be cached, so instead of fixing, perhaps the easy route of just
> don't cache it should be taken?

Perhaps, we will need to review all calls to get the tableDesc.

> 2) If we do keep the cache, I think we should move to a proper cache
> (e.g. Guava LoadingCache or somesuch) that has proper
> evictions/invalidation.  Anyone have strong feelings on that?

The evictions will have to occur with ZooKeeper changes/updates not based
on timeouts as long as we stick with that restriction we could use any lib
to implement.

> 3) It feels weird/wrong to have useCache in the calling method - it
> seems like that should be an internal decision not one of the caller.
>  Thoughts on this?

The issue is that at certain times the cache is OK to use even if it's a
second or two out of sync with ZK.  Other times we have to know the correct
answer, and basically make a ZK call.  The whole point of the cache is to
remove ZK calls because of the performance impacts both on Blur and the
extra load on ZK.


> Thanks,
> --tim

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