[Ur] TechEmpower Benchmarks

[Adam Chlipala]

On 12/12/2013 07:17 AM, Vladimir Shabanov wrote:
> 2013/12/12 Adam Chlipala <adamc at csail.mit.edu 
> <mailto:adamc at csail.mit.edu>>
>
>
>     Interesting; so throwing at least one popular proxy in front
>     doesn't bring magic performance improvements.  That's at least
>     comforting from the perspective of not challenging my mental model
>     of how efficient the Ur/Web HTTP binaries are.
>
>
> I think nginx helped my benchmark only because of it fixed non-working 
> keep-alive. Since nginx uses the same Ur/Web's HTTP interface there 
> shouldn't be any improvements on a local machine. On a faraway machine 
> it could help by reducing network latency by not making new connection 
> for each request.

But would you expect that latency improvement now that keepalive is 
available?

> One more thing -- in postgres (and maybe other backends) there is a 
> read only transaction mode (BEGIN READ ONLY). As far as I understand 
> ur/web already knows whether transaction is read only or not. Setting 
> this mode could improve the speed of query handling. Maybe not much 
> but who knows.

The compiler can do conservative program analysis that usually guesses 
correctly about whether a transaction will write to the database.  In 
fact, that guess was already being calculated to use in XSRF protection, 
so I've taken your suggestion and used it to start transactions as 
read-only where it looks safe.  I don't see a performance difference on 
these particular benchmarks running in Postgres 8.4, but the real 
comparison uses Postgres 9.1, whose manual does suggest setting READ 
ONLY as a useful optimization for SERIALIZABLE transactions (which 
Ur/Web uses).

Thanks for the idea!
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