Lambda the Ultimate

Deconstructing Process Isolation.
Mark Aiken; Manuel Fahndrich; Chris Hawblitzel; Galen Hunt; James R. Larus. April 2006

Most operating systems enforce process isolation through hardware protection mechanisms such as memory segmentation, page mapping, and differentiated user and kernel instructions. Singularity is a new operating system that uses software mechanisms to enforce process isolation. A software isolated process (SIP) is a process whose boundaries are established by language safety rules and enforced by static type checking. With proper system support, SIPs can provide a low cost isolation mechanism that provides failure isolation and fast inter-process communication. To compare the performance of Singularity’s approach against more conventional systems, we implemented an optional hardware isolation mechanism. Protect domains are hardware-enforced address spaces, which can contain one or more SIPs. Domains can either run at the kernel’s privilege levels and share an exchange heap or be fully isolated from the kernel and run at the normal application privilege level. These domains can construct Singularity configurations that are similar to micro-kernel and monolithic kernel systems.

The paper concludes that hardware-based isolation incurs performance costs of up to 25-33%, while the lower cost of SIPs permits them to provide protection and failure isolation at a finer granularity than conventional processes.

Maybe it's time to revist the language-as-os theme...

It's been awhile since you posted. You know it, and I know it. Feeling a little guilty now?! You should :-)

If you are an editor or a long time member and haven't posted for some time, chances are I am sitting here wondering where you are and what you are up to. So are many of your fans among the LtU readership whom you are probably unaware of.

In fact several key contributors are MIA. I am not going to name names, but you know who you are.

If there are issues I need to be aware of, how about dropping a line? Otherwise, just know that your absence has been noticed...

P.S.

Longtime members wishing to join the editorial team are welcome, as always. Just let me know.

A nice article of J2ME programming made me wonder about alternatives to Java for J2ME development.

I know there are other apporaches to mobile development, including native Python on Nokia phones, but that's not what I am asking about. I mean languages that target the JVM. There are many alternative languages for the JVM. Do none of them provide J2ME support?

From what I could see Jython isn't an option since the interpreter alone needs more memory than found on normal phones.

JavaWorld has An introduction to JSR 223 for those that want to roll their own and target the JVM:

The upcoming Java Standard Edition 6.0 release will include an implementation of Java Specification Request 223, Scripting for the Java Platform. This JSR is about programming languages and their integration with Java. This article demonstrates the power and potential of JSR 223 through the implementation of a simple Boolean language.

Past LtU references to JSR 223: The original announcement in Sun, Zend push scripting for Java and a brief mention in the thread on Embedded Languages in Java.