Re: Slow I/O can break throttling of base backup

Antonin Houska <ah(at)cybertec(dot)at> wrote:

> It seems to be my bug. I'll check tomorrow.

I could reproduce the problem by adding sufficient sleep time to the
loop.

> Magnus Hagander <magnus(at)hagander(dot)net> wrote:
>> I wonder if the else if (sleep > 0) at the bottom of throttle() should just
>> be a simple else and always run, resetting last_throttle?

I agree. In fact, I could simplify the code even more.

Since (elapsed + sleep) almost equals to GetCurrentIntegerTimestamp(), we can
use the following statement unconditionally (I think I tried too hard to avoid
calling GetCurrentIntegerTimestamp too often in the original patch):

throttled_last = GetCurrentIntegerTimestamp();

Thus we can also get rid of the "else" branch that clears both "sleep" and
"wait_result".

(The patch contains minor comment refinement that I found useful when seeing
the code after years.)

--
Antonin Houska
Cybertec Schönig & Schönig GmbH
Gröhrmühlgasse 26
A-2700 Wiener Neustadt
Web: http://www.postgresql-support.de, http://www.cybertec.at