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<title>JSR 166 Snapshot Introduction.</title> |
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<h1>JSR 166 Snapshot Introduction.</h1> |
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|
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by <a href="http://gee.cs.oswego.edu/dl">Doug Lea</a> |
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<p> |
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|
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To join a mailing list discussing this JSR, go to: |
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<A HREF="http://altair.cs.oswego.edu/mailman/listinfo/concurrency-interest"> http://altair.cs.oswego.edu/mailman/listinfo/concurrency-interest</A> . |
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|
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<p> |
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<em> |
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Disclaimer - This prototype is experimental code developed as part of |
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JCP JSR166 and made available to the developer community for use |
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as-is. It is not a supported product. Use it at your own risk. The |
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specification, language and implementation are subject to change as a |
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result of your feedback. Because these features have not yet been |
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approved for addition to the Java language, there is no schedule for |
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their inclusion in a product. |
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</em> |
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<p> JSR166 introduces package <tt>java.util.concurrent</tt> containing |
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utility classes commonly useful in concurrent programming. Like |
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package java.util, it includes a few small standardized extensible |
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frameworks, as well as some classes that provide useful functionality |
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and are otherwise tedious or difficult to implement. JSR-166 focusses |
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on breadth, prviding critical functionality useful across a wide range |
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of concurrent programming styles and applications, ranging from |
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low-level atomic operations, to customizable locks and synchronization |
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aids, to various concurrent data structures, to thread pools. |
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Descriptions of the main components may be found in the associated |
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package documentation. |
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|
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<p> JSR166 also includes a few changes and additions in packages |
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outside of java.util.concurrent. Here are brief descriptions. |
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<h2>Queues</h2> |
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A basic (nonblocking) {@link java.util.Queue} interface extending |
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java.util.Collection is introduced into java.util. Existing class |
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java.util.LinkedList is adapted to support Queue, and a new |
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non-thread-safe {@link java.util.PriorityQueue} is added. |
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<h2>Uncaught Exception Handlers</h2> |
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The java.lang.Thread class is modified to allow per-thread |
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installation of handlers for uncaught exceptions. Ths optionally |
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disassociates these handlers from ThreadGroups, which has proven to be |
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too inflexible in many multithreaded programs. (Note that the |
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combination of features in JSR166 make ThreadGroups even less likely |
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to be used in most programs. Perhaps they will eventually be |
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deprecated.) |
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<h2>High precision timing</h2> |
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Method <tt>nanoTime</tt> is added to <tt>java.lang.System</tt>. It |
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provides a high-precision timing facility that is distinct from |
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and uncoordinated with <tt>System.currentTimeMillis</tt>. |
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<h2>Removing ThreadLocals</h2> |
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The java.lang.ThreadLocal class now supports a means to remove a |
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ThreadLocal, which is needed in some thread-pool and worker-thread |
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designs. |
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<hr> |
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<address><A HREF="http://gee.cs.oswego.edu/dl">Doug Lea</A></address> |
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</body> |
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</html> |
