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Subject: Re: [nodejs] Re: v0.8 Roadmap
From: Jorge <jo...@jorgechamorro.com>
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References: <CA+fPNJW=Su55G9M9+-DZzVbefPqHfJhkH2_P0VxQi3Wwf5a...@mail.gmail.com> <6e71605e-febd-4d78-8a38-11b15a723997@googlegroups.com>
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On 26/06/2012, at 02:43, GuoQing Deng wrote:

> Free Node.js eBook update: http://www.heronote.com/files/Node.js.htm=20=



> "Furthermore, users of Node are free from worries of dead-locking the =
process=97there are no locks."

Neither in a bunch of httpd processes.

> "But what about multiple-processor concurrency? Aren't threads =
necessary to scale programs to multi-core computers?"

-YES: Threads are necessary to scale programs to multi-core computers.

> "Processes are necessary to scale to multi-core computers"

-Processes *are* threads.

> "not memory-sharing threads."

-Processes *are* threads running in isolated memory spaces, and it's so =
for security reasons *not* for performance reasons.
-The ability to share memory is always a plus.
-The threads in a process share what they want to share and if they want =
to. They can also share nothing as processes do.

> "The fundamentals of scalable systems are fast networking and =
non-blocking design=97"

-But node uses multiple threads itself both to *parallelize* IO and to =
avoid blocking on IO. But it doesn't expose any threads API to its =
users.

> "the rest is message passing."

-There's no fastest way to pass a message than via a pointer and you =
can't do that across processes but you can do it across threads.

> "In future versions, Node will be able to fork new processes (using =
the Web Workers API ) which fits well into the current design."

-In other words, to exploit multiple cores node will do just what =
everybody else has been doing until now, say, httpd: fork itself.


threads_a_gogo(*) gives node users the power to parallelize the =
execution of their javascript code within a single node process. Node =
couldn't benefit before threads_a_gogo of multi-core cpus simply because =
it was lacking a threads API. But threads_a_gogo gives you one:

(*) <https://github.com/xk/node-threads-a-gogo/>
--=20
Jorge.=