[SATLUG] The "Second Coming" of Java

Jonathan Kelley jonkelley at gmail.com
Wed Sep 25 19:19:09 CDT 2013


I use to think the JVM was just magic and smoke in Linux and that's why
it's bad.
The JVM _is_ magic and smoke to Linux, but these days I understand why.

Linux is merely your parent host to the Java Virtual machine. Your java
virtual machine is the real computer/processor that runs your containers
and threads containing application code, and it has its own binary
instruction set. It has its own heaps sub-partitioned and reserved within
the memory table, etc.

So of course the Linux tools of management are worthless, they interact
with the Linux kernel and userland, and the Java Virtualmachine ___is___
smoke and mirrors.  System calls to the kernel from the virtualmachine are
abstracted away from the applications actions, usually causing the loss of
the ability to track the performance of Java applications within Linux
userspace.

As a Linux operator, you have to forget you're using Linux at this point.
But there's a java tool for everything to debug JVM stuff. (JCONSOLE, heap
tools, heap analysis, etc) These tools in fact can tell you more about your
applications health per thread better than Python/Ruby or any other
language --- and its no hackery, it ships natively with the JVM!

Not to mention threading works flawlessly with no global semaphores in
namespace (pythons global interpreter lock syndrome, oh no!)

I think with a suitable language to put under the JVM it can be an awesome
method of executing code.
For me, Scala feels way complicated working with it and requires a certain
appreciation for pain, but the JVM can be an awesome platform for running
applications which makes it suitable for production if you have Scala skill.

--
Jon



On Wed, Sep 25, 2013 at 5:25 PM, David Kowis <dkowis at shlrm.org> wrote:

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>
> "Twitter builds some of its code with the Java programming language,
> but it fashions the majority with Scala (a language that, for many
> programmers, lets you create software with an ease that eclipses Java)
> and a bit with Clojure (a language that feels like Lisp, a way of
> quickly scripting code that has been a mainstay for decades). LinkedIn
> mostly uses the Java programming language, while sprinkling in some
> Scala. But the common denominator is the JVM, software that has been
> finely tuned over the past fifteen years to run code at speed."
>
> http://www.wired.com/wiredenterprise/2013/09/the-second-coming-of-java/
>
>
> I don't buy the Second Coming of Java, but of the JVM. Without
> significant changes the Java Language will fall by the wayside
> eventually, something more expressive and powerful will take it's
> place. I'm placing my bet on Scala right now.
>
> - --
> David
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> --
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