October 2011
Intermediate to advanced
126 pages
3h 10m
English
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Chapter 3. multicore
multicore is a popular parallel
programming package for use on multiprocessor and multicore computers. It
was written by Simon Urbanek, and first released on CRAN in 2009. It
immediately became popular because its clever use of the fork() system call allows it to implement a
parallel lapply() operation that is even
easier to use than snow’s parLapply().
Unfortunately, because fork() is a
Posix system call, multicore can’t really
be used on Windows machines.[33] Fork() can also cause
problems for functions that use resources that were allocated or initialized
exclusively for the master, or parent process. This is particularly a
problem with graphics functions, so it isn’t generally recommended to use
multicore with an R GUI.[34] Nevertheless, multicore
works perfectly for most R functions on Posix systems, such as Linux and Mac
OS X, and its use of fork() makes it very
efficient and convenient, as we’ll see in this chapter.
Quick Look
Motivation: You have an R script
that spends an hour executing a function using lapply() on your laptop.
Solution: Replace lapply() with the mclapply() function from the multicore package.
Good because: It’s easy to install, easy to use, and makes use of hardware that you probably already own.
How It Works
multicore is intended to run on Posix-based multiprocessor and multicore systems. This includes almost all modern Mac OS X and Linux desktop and laptop computers. It can also be used on single nodes of a Linux cluster, for example, but ...
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O’Reilly covers everything we've got, with content to help us build a world-class technology community, upgrade the capabilities and competencies of our teams, and improve overall team performance as well as their engagement.Julian F.
I wanted to learn C and C++, but it didn't click for me until I picked up an O'Reilly book. When I went on the O’Reilly platform, I was astonished to find all the books there, plus live events and sandboxes so you could play around with the technology.Addison B.
I’ve been on the O’Reilly platform for more than eight years. I use a couple of learning platforms, but I'm on O'Reilly more than anybody else. When you're there, you start learning. I'm never disappointed.Amir M.
I'm always learning. So when I got on to O'Reilly, I was like a kid in a candy store. There are playlists. There are answers. There's on-demand training. It's worth its weight in gold, in terms of what it allows me to do.