InfoQ Homepage Concurrency Content on InfoQ
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Dynamic Language Roundup: Python's GIL Gets Overhauled but not Removed, Squeak Comes to Android
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.
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ConcurrentDictionary, .NET 4.0’s New Thread-Safe Hashtable
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.
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Clojure 1.1 Adds Transients, Chunked Sequences for Efficiency
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.
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Beta 2 Brings Refinements to .NET’s Coordination Data Structures Library
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.
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Google Experiments with a New Language, Go
Go is a Google experimental open source new language resembling C but adding features like reflection, garbage collector, dynamic types, concurrency, and parallelism.
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Introducing the Task Parallel Library’s new Cancellation Framework
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.
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Ruby VM Roundup: MacRuby Progress, IronRuby, Ruby 1.9.2 Delay
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.
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A Type System for Scala Actors to Enforce Race Safety Without Sacrificing Performance
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.
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Exploring Tuple Spaces Persistence In Ruby With Blackboard
Ruby has long been criticized for 1.8's limited green threads. Luc Castera gave a presentation at RubyNation about Concurrent Programming with Ruby and Tuple Spaces. He introduces 2 ways of implementing TupleSpaces in Ruby: Rinda and Blackboard using Redis (with plans to porting it to Erlang).
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MacRuby Drops GIL, Gains Concurrent Threads
MacRuby joins the ranks of JRuby and IronRuby and moved away from Ruby 1.9's Global Interpreter Lock (GIL) in the experimental branch.
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Rich Hickey on Clojure's Features and Implementation
In this interview from QCon London 2009, Rich Hickey talks about Clojure. The discussion includes the ideas behind Clojure's STM support, what other concurrency primitives Clojure supports and which ones might get added in the future. Other topics covered are Clojure's AOT support, the role and implementation of multimethods, Clojure ports to other systems and much more.
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Declarative Concurrency For Ruby With Dataflow
Part of the Ruby language was influenced by functional programming techniques. Larry Diehl brings a declarative concurrent model to Ruby by importing the concept of unification from Oz Language with the Dataflow project.
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Is Parallel Programming Hard? Prof. Guy Blelloch Argues That It Isn’t
In an essay on Cilk Arts, Professor Guy Blelloch argues that parallel programming is not intrinsically hard, but rather a question of abstraction. The three problems identified by Blelloch are a lack of training in parallel thinking, separating parallel implementation from algorithms, and determinism. After detailing each, he explains why he thinks they can be overcome.
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Sun's Garbage First Collector Largely Eliminates Low Latency/High Throughput Tradeoff
In a recent podcast, James Gosling talked to Danny Coward about the significance of Sun's new Hotspot garbage collector Garbage First for developers of large-scale enterprise systems.
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Functional Programming and Coordination Data Structures
Coordination Data Structures, CDS, are a new set of thread-safe objects, mostly collections, planned for .NET 4. After about 6 months of silence, there have been some significant updates. Most notably is the inclusion of functional programming techniques to reduce the need for design patterns.