Re: [Tarantool-patches] [PATCH v3] wal: introduce limits on simultaneous writes

[Konstantin Osipov via Tarantool-patches <tarantool-patches@dev.tarantool.org>]

* Vladislav Shpilevoy via Tarantool-patches <tarantool-patches@dev.tarantool.org> [21/03/09 23:44]:
> Hi! Thanks for the patch!
> 
> LGTM.
> 
> > https://github.com/tarantool/tarantool/issues/5536
> > https://github.com/tarantool/tarantool/tree/sp/gh-5536-replica-oom

I don't understand why you need two parameters, size and len. What
difference does it make how many requests are in the queue? The
queue is IO and memory bound, not CPU bound, at least not more cpu
bound than any other subsystem.

Pushing the problem to the user by forcing them to choose not one,
but two configuration values is poor design. How am I supposed to
know what is the right value for the option? 

I guess don't know it either - the patch was not followed by
a benchmark which would prove the selected defaults are optimal.

Tarantool has an incoming throttling limit which makes the whole
system work like a clock: it's the fiber  pool size and net msg
size. They were carefully selected after days and weeks of
testing. 

-- 
Konstantin Osipov, Moscow, Russia