From: Urabe Shyouhei <shyouhei@...>
Date: 2012-04-09T16:24:26+09:00
Subject: [ruby-core:44214] Re: Questions about thread performance (with benchmark included)

#### MRI threads myths and facts #####

Myth1: "Forking processes to run parallel wastes memory"

The fact is, no.  You can waste memories if you wish, but that is also
true for threading.  With a  careful implementation a process is quite
small in  memory consumption.   If you are  in doubt, see  how unicorn
forks its child processes.

Myth2: "Threading boosts your application performance"

This is also no.  Multi-threaded programming is _very_ difficult to do
properly.  And  if you  do it badly,  its performance gets  even worse
than a  single threaded one.   A multi-threaded application  that does
scale can also scale much easily by using processes.

Myth3: "Threading is the way to go"

This is  quite doubtful.  Multi-threaded programming  is too difficult
to  develop, almost  impossible to  debug,  and normally  do not  work
properly.   Multi-threading  is too  easy  to  fail.  Some  restricted
model, such  as Shared Nothing  architecture, seems to have  much more
potential.

Myth4: "We are ignoring Rais"

Definitely no.

Myth5: "You can make MRI lock-free"

Do it yourself if you think so.  Patch welcomed.