I was surprised to read, in Mark Reinhold's post "There's not a moment to lose!", that the primary objective, or use case, behind Sun's sudden desire to add closures to Java is multi-core processors. I mean, it's not like multi-core processors are a brand new development, a stunning revolutionary technology that has popped up out of nowhere!
Still, it's quite true that, while the typical new PC even for home use has 2 or 4 cores today, very little mainstream software has been redesigned to take advantage of multiple cores. Rather, the gain in speed comes from the possibility of an individual core being fully tasked running a single foreground application, while the other cores take care of background and OS processes.
It has actually surprised me a bit, how slow companies have been to develop multithreaded apps. Of course, many of the most commonly used desktop applications are highly interactive. In that case, much more time is spent by the user deciding what to input or where to move the mouse than is spent by the computer processing the user's requests for action. And, also, much of people's activity as they sit in front of their computers today actually takes place on a remote server somewhere -- so, again, when your computer is serving as a smart terminal, having that terminal application (for example, your browser) multithreaded isn't really critical, since much of your wait time is likely to be your network connection anyway. But, still, it's hard to picture a future where 16 and 32 core PCs are inexpensive and the marketplace is not demanding that those cores be utilized to speed up our computer-based activities. Has there ever been a time when we thought our software applications ran too fast?
A couple years ago, I participated in the launch of Intel's open source Threading Building Blocks (TBB) project. I was the community manager for that project for its first nine months. TBB is a C++ threading library. It's objective is to facilitate development of multithreaded C++ applications that can take full advantage of multicore processors. In some cases, existing software can be "parallelized" automatically by wrapping the code in TBB structures. TBB represents a significant and formidable advance for the C++ world, when it comes to development for multicore/multiprocessor systems, in my view.
But, getting back to Java and closures: Mark links to the "Connection with closures" section of an IBM Developer Works paper. This section talks about ParallelArray, which "offers a nice way to declaratively specify filtering, processing, and aggregation operations on data sets, while also facilitating automatic parallelization." Later on:
one of the arguments in favor of closures is that it makes expressing small snippets of code - such as filters, mappers, and reducers in ParallelArray - much more compact.
Looking at the code snippet that follows (Listing 4 in the article), I am indeed reminded of some of the TBB constructs I was working with a couple years ago. The code snippet is part of a set of routines that compute the maximum GPA for graduating students. The snippet uses the closure syntax from the BGGA proposal. Here's the code:
double bestGpa = students.withFilter({Student s => (s.graduationYear == THIS_YEAR) })
.withMapping({ Student s => s.gpa })
.max();
Needless to say, for me, the entire closures discussion is becoming very interesting. But, I'm still a bit confused. For example, Java has had threads for a very long time. So, I would have thought that the concept of programming for multicore processors would have received a lot of attention in the past. And it's still confusing to read that suddenly right now is when Java must react to the advent of multi-core processors. This wasn't being thought about four or five years ago? Also, I see almost nothing about multi-core processors and multithreaded programming in the primary closures proposals. So, as I say, I find closures as a response to the multicore challenge, at this time, a quite surprising -- but nonetheless very interesting -- development.
The free lunch is over. Multicore processors are not just coming—they’re here. Leveraging multiple cores requires writing scalable parallel programs,
which is incredibly hard. Tools such as fork/join
frameworks based on work-stealing
algorithms make the task easier, but it still takes a fair bit of expertise
and tuning. Bulk-data APIs such as parallel
arrays allow computations to be expressed in terms of higher-level,
SQL-like operations (e.g., filter, map, and reduce) which can be mapped
automatically onto the fork-join paradigm. Working with parallel arrays in Java, unfortunately, requires lots
of boilerplate code to solve even simple problems...
The JVM Language Summit 2009 took place in September. The first video of a full talk is now available on InfoQ, and it's Rich Hickey's keynote, "Are We There Yet?". John Rose has blogged about his paper on "Bytecodes meet Combinators: invokedynamic on the JVM" for the VMIL workshop at OOSPLA on the internals and implications of adding invokedynamic to the JVM...
I have always wondered why CFSCRIPT was never Javascript, but instead a half-way house. This is something I have spoken about before in various blogs and forums. I have made no secret of the fact that I have not been a fan of CFSCRIPT and feel it was a lost opportunity. Javascript has taken the development world by storm, with it now being one of the fastest growing languages out there. In short, there is a lot of Javascript talent out there, and I want them to be able to utilise this talent server-side, within CFML applications...
There was a bunch of good things to see at this years Devoxx. My personal highlights are ScalaTest (you definitively want to look into this when testing concurrency in any java code ... the best way to test different race scenarios I've seen so far). Another highlight was the amount of work done on JavaFX yet. The new UI for the clickable gui builder shown briefly by Tor ... surely you remember when Tor has shown this thing for the first time on JavaOne ... well, guess what, since then, the UI have been completely re-written and is using FX only. This language has a potential for building the slick UIs (and not only games, tho those are also very interesting ... check work by Rich and Jasper) ...
1:00-1:45 pm
Show Me the Money!
by Kristen Knight, Kynetx VP Product Management
Monetizing cross-site, context-sensitive apps, revenue models, VAR &
Implementor business opportunities.
Wal-Mart
- generated their own warehousing and distribution infrastructure
rather than depending on manufacturers or 3rd party distributors
Before Kynetx:
- search engines (3rd party) direct people to YOUR site
- website sales funnel
With Kynetx:
- consumer/community is center
- search engine, web-enabled devices, other people's sites, desktop, on you site...
In the Forums, kleopatra has a question about Appframework: how-to restore session state dynamically?: "Works fine for everything actually added to the demo app at startup. Problem are that the demo pages themselves are loaded and added only when selected. Any way to restore their state? And if so, how-to? BTW, in case you have not noticed yet:..."
ntimesc has a question Regarding stateful webservices: "Hi All, i have implemented stateful web servies using following mechanism enable a binding property at client side: ((BindingProvider)port).getRequestContext().put(BindingProvider.SESSION_MAINTAIN_PROPERTY, ..."
xclaim wonders how to stop/exit the mediabox: "hi. may i know how to exit the mediabox? for example i create a group inside that is the mediabox, but when i click the close button(custom button) it will go to the other group and thus exit the mediabox. current situation is..."
In our current Spotlight, Terrence Barr invites us to Check out Java Card 3.0 Connected Edition: Real Java, just really flat ;-): "Java Card 3.0 was released a couple of months ago – and the second update (version 3.0.2) is scheduled for December. If you haven’t paid much attention to Java on smart cards because you thought it’s not “real” Java – well, look again. It’s true that Java Card 2 was very limited in many ways – a testament to the kind of technology you had available on smart cards 10 years ago. There are billions of these out there today..."
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