On Sat, 2011-10-22 at 04:32 -0700, opinali wrote: [ . . . ] > The single serious criticism I've ever heard about j.u.c. and the continuing > work of JSR-166, is that it furthers the paradigm of shared-memory > concurrency. But, like it or not, it's the appropriate thing to do at the > level of the JavaSE platform and Java Language. Then you can use these as > [extremely good] building blocks for higher-level languages and concurrency > frameworks, like Scala+Actors etc. And j.u.c. is well designed to > accommodate future innovation at the runtime or language levels - from Java > syntax sugar a la C# 5, to lambdas, coroutines, affinnity..., all these > things will be easy to fit, indeed they have been considered in the design.
Well here we have a real bone of contention. Java reified shared memory multithreading in the early 1990s. It was an error then and is certainly an error now -- at least as being pushed as the "one true way" of concurrency since it makes parallelism very hard. Why should it remain the "one true way" in Java? It is this closed mindset that is a big problem with Java. Java should have actor libraries, dataflow libraries, CSP, that applications folk use. Certainly shared memory multithreading is an important framework level technique, but no applications programmer should ever have to use such a low level model of concurrency and parallelism. GPars (http://gpars.codehaus.org) brings all of these things to Groovy and Java programmers. JCSP is a CSP framework for Java. DataRush is a commercial offering from Pervasive that offers dataflow. These models thrash explicit use of shared memory multithreading for applications development. Please can we ditch the idea that Java means using shared memory multithreading and that to use other models we have to use other languages. It is not true and it is damaging in the face of ubiquitous parallel hardware. -- Russel. ============================================================================= Dr Russel Winder t: +44 20 7585 2200 voip: sip:[email protected] 41 Buckmaster Road m: +44 7770 465 077 xmpp: [email protected] London SW11 1EN, UK w: www.russel.org.uk skype: russel_winder
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