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From Jonathan Ellis <jbel...@gmail.com>
Subject Re: ConsistencyLevel.ZERO
Date Wed, 07 Apr 2010 16:06:11 GMT
Great!

On Wed, Apr 7, 2010 at 11:02 AM, Paul Prescod <prescod@gmail.com> wrote:
> On Tue, Apr 6, 2010 at 10:58 AM, Tatu Saloranta <tsaloranta@gmail.com> wrote:
>> On Tue, Apr 6, 2010 at 8:17 AM, Jonathan Ellis <jbellis@gmail.com> wrote:
>>> On Tue, Apr 6, 2010 at 2:13 AM, Ilya Maykov <ivmaykov@gmail.com> wrote:
>>>> That does sound similar. It's possible that the difference I'm seeing
>>>> between ConsistencyLevel.ZERO and ConsistencyLevel.ALL is simply due
>>>> to the fact that using ALL slows down the writers enough that the GC
>>>> can keep up.
>>>
>>> No, it's mostly due to ZERO meaning "buffer this locally and write it
>>> when it's convenient," and buffering takes memory.  If you check your
>>> tpstats you will see the pending ops through the roof on the node
>>> handling the thrift connections.
>>
>> This sounds like a great FAQ entry? (apologies if it's already included)
>> So that ideally users would only use this setting if they (think they)
>> know what they are doing. :-)
>
> I added this note to the API docs:
>
>  * ConsistencyLevel.ZERO: Ensure nothing. A write happens
> asynchronously in background. If too many of these queue up, buffers
> will explode and bad things will happen.
>
> Apologies if I violated any community conventions. I'm happy to fix
> the text if someone has a better suggestion.
>
>  Paul Prescod
>

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