Re: Parallel serialization and writes ? (Was: ACIDity of Prevayler 2.6)

I ran my test on a Windows Vista PC, and it seems that os.getFD().sync() 
has no effect on that OS (?).

On a Windows 7 PC, the test gives 77ms which is more similar to what you 
have observed.


On 19/11/2012 04:51, Justin T. Sampson wrote:
> On Sun, Nov 18, 2012 at 2:09 AM, Arnaud Masson <[email protected]
> <mailto:[email protected]>> wrote:
>
>     1) 50ms-100ms seems a large value (especially on SSD).
>
>
> Hmm. SSD does change the picture a bit. :) But 100ms is definitely what
> I remember from running the Prevayler scalability tests on a hard disk
> 5+ years ago. I remember getting throughput maxing out close to 1000
> transactions per second, with roughly 100 per batch and 10 batches per
> second (i.e. 100ms each).
>
>     2)  "Adding ... latency to _every_ query"
>     This is the worst case scenario, isn't it?
>
>
> Ha, yeah. Though we could think of it as the _best_ case, because it
> means your app is popular. :)
>
> With a 100ms transaction write latency, it just takes 10 POSTs per
> second to affect every GET. If an SSD allows, say, a 10ms transaction
> write latency, then it would take 100 POSTs per second to affect every
> GET, which I admit is a pretty intense load. I think typical webapps
> have roughly 1% to 10% of requests being POSTs, so you're right that it
> might not be an issue as long as you're not getting thousands of
> requests per second.
>
>
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