Feeds

A Deadlock Holiday

What to do now there's no Moore's Law?

Internet Security Threat Report 2014

Shang Erlang

Finally we come to my hot tip for concurrency champion. Erlang is the functional language that differentiates itself from its competition by having been around for nearly 25 years. No danger of being burned by V1.0 compiler bugs, then.

Erlang has a very different paradigm from procedural languages. For one thing, its so-called variables are WORM (Write Once Read Many), like 1990s backup media. Presumably its designers at Ericsson thought to encourage programmers to jolly well get it right first time.

The style of programming relies heavily on recursion and pattern matching. For example, a simple Erlang routine to perform a factorial might exploit the fact that, for example, 

20! = 21! / 21 

Generalising this into code, and adding pattern matching to supply the stopping condition, we have a definition for a fact() function:

fact(∞) -> ∞; % Exploit the fact that ∞! = ∞;
fact(N) -> fact(N+1)/(N+1).

Don't worry about that use of very large numbers there - Erlang uses arbitrary-sized integers, so it won't fall over just because we pass the 64-bit limit! (Actually, that example doesn't look quite right. Perhaps you better google it up before you use it. I don't think it implements proper tail recursion.)

Anyway, Erlang programs are organised as lots of independent-but-lightweight processes, which communicate by sending messages to each other. There is no shared state, which means all that ghastly business with races and locks and lavatories I have been discussing just goes away, and your programs are automatically parallel without any extra work on your part.

Finally, there is one particular Erlang trick which I think is the clincher - and must surely impress all who have returned to an overnight run test on a Windows box to discover that the machine has instead automatically been rebooted in order to update some security-compromised DLL or other. You can update running Erlang programs on the fly. That in my view is the feature rival systems need to top. Happy parallelising.

Revision Questions

  1. If your double-checked locking is broken on a multi-core machine (it is), explain why this isn't observable behaviour.
  2. Which is trendier: to eschew mere multicore programming and dump all your hard processing onto the GPU? Or port it all to Occam and start a campaign to reinstate transputers as the Next Big Thing? Show your working. ®

Secure remote control for conventional and virtual desktops

More from The Register

next story
ONE MILLION people already running Windows 10
A third of them are doing it in VMs, but early feedback focuses on frippery
Netscape Navigator - the browser that started it all - turns 20
It was 20 years ago today, Marc Andreeesen taught the band to play
Sway: Microsoft's new Office app doesn't have an Undo function
Content aggregation, meet the workplace ... oh
Sign off my IT project or I’ll PHONE your MUM
Honestly, it’s a piece of piss
Do Moan! MONSTER 6-day EMAIL OUTAGE hits Domain Monster
Customers freaked out by frightful service
Ploppr: The #VultureTRENDING App of the Now
This organic crowd sourced viro- social fertiliser just got REAL
Return of the Jedi – Apache reclaims web server crown
.london, .hamburg and .公司 - that's .com in Chinese - storm the web server charts
NetWare sales revive in China thanks to that man Snowden
If it ain't Microsoft, it's in fashion behind the Great Firewall
prev story

Whitepapers

Forging a new future with identity relationship management
Learn about ForgeRock's next generation IRM platform and how it is designed to empower CEOS's and enterprises to engage with consumers.
Win a year’s supply of chocolate
There is no techie angle to this competition so we're not going to pretend there is, but everyone loves chocolate so who cares.
Why cloud backup?
Combining the latest advancements in disk-based backup with secure, integrated, cloud technologies offer organizations fast and assured recovery of their critical enterprise data.
High Performance for All
While HPC is not new, it has traditionally been seen as a specialist area – is it now geared up to meet more mainstream requirements?
Saudi Petroleum chooses Tegile storage solution
A storage solution that addresses company growth and performance for business-critical applications of caseware archive and search along with other key operational systems.