Brian Goetz and Cliff Click spoke at JavaOne conference last week about concurrency revolution from a hardware perspective. They said CPU designers will focus on parallelism in the future for increasing throughput of the systems. They also discussed some point solutions like Thread Pools, Fork/Join, Map/Reduce and Actors to achieve the concurrency in applications.
Dana Groff has announced the end of Microsoft’s experiment with software transactional memory for the .NET Framework. Known as STM.NET, this research project was announced in 2008 as an alternative to explicit locks when dealing with concurrency issues.
Even though Microsoft has been working on .NET’s Parallel Extensions since 2007, there are still many features that they didn’t have time to fully implement for .NET 4.0. Some features were “too application-specific to be included in the core of the Framework” while others simply needed for testing and user feedback. So instead they are being released as a set of patterns and samples.
The strong correlation between heap size and garbage collection pause time is becoming one of the major limitations to Java application scalability, and a great deal of R&D effort is going into trying to remedy the situation. InfoQ talked to Dr. Cliff Click, former architect and lead developer of the HotSpot Server Compiler and now chief JVM Architect at Azul Systems, about Azul's solution.
JRuby-Prof is a new, low overhead profiler for JRuby which, unlike plain Java profilers, will generate clear, Ruby-specific reports. A new feature in JRuby is JRuby::Synchronized, a module that, when extended, will make all methods of a class synchronized.
Today, the Akka team released version 0.7 of their actors framework for the Java Virtual Machine. Akka attempts to address future concurrency challenges with a solution relying on message based actors, software transactional memory and appropriate fault handling strategies. InfoQ talked to Jonas Bonér about the intent behind Akka, its current state and adoption, and future plans.
MacRuby 0.5 has been released, with a new VM, AOT and JIT support. The GIL MacRuby inherited from Ruby 1.9 is now gone and Grand Central Dispatch support allows to keep a system's cores busy with Ruby threads. Work on the 0.6 release is already under way; a new debugger feature is already available in the trunk.
The Unladen Swallow project that aims to speed up Python has proposed to be merged into mainstream Python. One of Unladen Swallow's goals was to remove the GIL; a new implementation of Python's GIL by Antoine Pitrou will be fairer and less intrusive on multicore CPUs. Also: Squeak Smalltalk has been ported to Android.
The ConcurrentDictionary is a cornerstone in .NET 4.0’s greatly increased emphasis on parallel and concurrent programming. But while vastly superior to what we have seen in the past, it isn’t a panacea and developers need to study its semantics carefully.
Clojure 1.1 RC1 is out and cuts the overhead of functional programming with a few new constructs: transients bring controlled mutability for persistent data structures; chunked sequences make lazy sequences more efficient. InfoQ takes a look at what makes these improvements work.
Coordination Data Structures (CDS) is designed both to be used directly and to act as the building blocks for more complex concurrency frameworks. It includes advanced synchronization tools like the Barrier, several thread-safe collections, and a couple different ways to create futures.
Go is a Google experimental open source new language resembling C but adding features like reflection, garbage collector, dynamic types, concurrency, and parallelism.
Task Parallel Library, .NET 4.0’s replacement for ThreadPool, got a face lift for beta 2. In addition to performance improvements, it The most important change is probably the new cancellation framework that replaces parent/child relationships with cancellation tokens that can be freely given to logical groups of tasks.
MacRuby is nearing its first RC for 0.5 and adds support for Grand Central Dispatch. A new IronRuby release is available, Ruby 1.9.2 might be delayed, and Rubinius joins the group of 1.8.7 compliant Ruby implementations.
Philipp Haller and Martin Odersky introduce a type system that enables safe massage transfer in Scala actors. Formalized as an extension of the EPFL Scala compiler, “Object Capability Types” system, based on capability checking and external uniqueness, enforces race safety without sacrificing performance and removes significant limitations on message shape imposed by existing approaches.