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revision 1.10 by tim, Wed Aug 6 16:04:58 2003 UTC revision 1.25 by jsr166, Fri Mar 25 05:38:25 2016 UTC
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1  <!DOCTYPE HTML PUBLIC "-//IETF//DTD HTML//EN">  <!DOCTYPE HTML PUBLIC "-//IETF//DTD HTML//EN">
2  <html>  <html>
3   <head>   <head>
4     <title>JSR 166 Community Review Draft Introduction.</title>     <title>JSR 166 Introduction.</title>
5    </head>    </head>
6    
7    <body bgcolor="#ffffee" vlink="#0000aa" link="#cc0000">    <body bgcolor="#ffffee" vlink="#0000aa" link="#cc0000">
8    <h1>JSR 166 Community Review Draft Introduction.</h1>    <h1>JSR 166 Introduction.</h1>
9    
10    by <a href="http://gee.cs.oswego.edu/dl">Doug Lea</a>    by <a href="http://gee.cs.oswego.edu/dl">Doug Lea</a>
11    <p>    <p>
12    
13  To chack for updates to this draft, access a preliminary prototype  This is maintenance repository of JSR-166 specifications.  For further
14  release of main functionality, or join a mailing list discussing this  information, go to: <A
 JSR, go to: <A  
15  HREF="http://altair.cs.oswego.edu/mailman/listinfo/concurrency-interest">  HREF="http://altair.cs.oswego.edu/mailman/listinfo/concurrency-interest">
16  http://altair.cs.oswego.edu/mailman/listinfo/concurrency-interest</A>  http://altair.cs.oswego.edu/mailman/listinfo/concurrency-interest</A>.
 .  
 <p>  
   
 <em> <b>Disclaimer</b>. The prototype implementation is experimental  
 code developed as part of JCP JSR-166 is made available to the  
 developer community for use as-is. It is not a supported product. Use  
 it at your own risk. The specification, language and implementation  
 are subject to change as a result of your feedback. Because these  
 features have not yet been approved for addition to the Java language,  
 there is no schedule for their inclusion in a product.  </em>  
   
 <p> <em> <b>Disclaimer</b>.  This draft specification was produced  
 using JDK1.4 tools plus some preprocessing. The resulting javadocs do  
 not yet correctly render other planned JDK1.5 constructs on which  
 JSR-166 relies, most notably the use of generic types. We are  
 releasing this version now (before the availability of JDK1.5-based  
 tools) because, even though they are misformatted and sometimes lack  
 proper cross-referencing, they otherwise convey the intended  
 specifications.  </em>  
17    
18  <p> JSR-166 introduces package <tt>java.util.concurrent</tt>  <p>JSR-166 introduces package <code>java.util.concurrent</code>
19  containing utility classes commonly useful in concurrent  containing utility classes commonly useful in concurrent
20  programming. Like package <tt>java.util</tt>, it includes a few small  programming. Like package <code>java.util</code>, it includes a few small
21  standardized extensible frameworks, as well as some classes that  standardized extensible frameworks, as well as other classes that
22  provide useful functionality and are otherwise tedious or difficult to  provide useful functionality and are otherwise tedious or difficult to
23  implement.  implement.
24    
25  <p>JSR-166 focusses on breadth, providing critical functionality  <p>JSR-166 focuses on breadth, providing critical functionality
26  useful across a wide range of concurrent programming styles and  useful across a wide range of concurrent programming styles and
27  applications, ranging from low-level atomic operations, to  applications, ranging from low-level atomic operations, to
28  customizable locks and synchronization aids, to various concurrent  customizable locks and synchronization aids, to various concurrent
29  data structures, to high-level execution agents including thread  data structures, to high-level execution agents including thread
30  pools. This diversity reflects the range of contexts in which  pools. This diversity reflects the range of contexts in which
31  developers of concurrent programs have been found to require or desire  developers of concurrent programs have been found to require or desire
32  support not previously available in J2SE, which also keeping the  support not previously available in J2SE, while also keeping the
33  resulting package small; providing only that minimial support for  resulting package small; providing only functionality that has been
34  which it makes sense to standardize.  found to be worthwhile to standardize.
35    
36  <p>Descriptions and brief motivations for the main components may be  <p>Descriptions and brief motivations for the main components may be
37  found in the associated package documentation.  JSR-166 also includes  found in the associated package documentation.  JSR-166 also includes
# Line 62  java.util.concurrent.  Here are brief de Line 42  java.util.concurrent.  Here are brief de
42    
43  A basic (nonblocking) {@link java.util.Queue} interface extending  A basic (nonblocking) {@link java.util.Queue} interface extending
44  {@link java.util.Collection} is introduced into  {@link java.util.Collection} is introduced into
45  <tt>java.util</tt>. Existing class {@link java.util.LinkedList} is  <code>java.util</code>. Existing class {@link java.util.LinkedList} is
46  adapted to support Queue, and a new non-thread-safe {@link  adapted to support Queue, and a new non-thread-safe {@link
47  java.util.PriorityQueue} is added.  java.util.PriorityQueue} is added.
48    
49  <h2>Threads</h2>  <h2>Threads</h2>
50    
51  Two minor changes are introduced to the {@link java.lang.Thread}  Three minor changes are introduced to the {@link java.lang.Thread}
52  class: It now allows per-thread installation of handlers for uncaught  class:
53  exceptions. Ths optionally disassociates handlers from ThreadGroups,  <ul>
54  which has proven to be too inflexible. (Note that the combination of    <li> It now allows per-thread installation of handlers for uncaught
55  features in JSR-166 make ThreadGroups even less likely to be used in    exceptions. This optionally disassociates handlers from ThreadGroups,
56  most programs. Perhaps they will eventually be deprecated.) Secondly,    which has proven to be too inflexible. (Note that the combination of
57  access checks are no longer required when a Thread interrupts    features in JSR-166 make ThreadGroups even less likely to be used in
58  <em>itself</em>.  The <tt>interrupt</tt> method is the only way to    most programs. Perhaps they will eventually be deprecated.)
59  re-assert a thread's interruption status (and in the case of  
60  self-interruption has no other effect than this).  The check here    <li> Access checks are no longer required when a Thread interrupts
61  previously caused unjustifiable and uncontrollable failures when    <em>itself</em>.  The <code>interrupt</code> method is the only way to
62  restricted code invoked library code that must reassert interruption    re-assert a thread's interruption status (and in the case of
63  to correctly propagate status when encountering some    self-interruption has no other effect than this).  The check here
64  <tt>InterruptedExceptions</tt>.    previously caused unjustifiable and uncontrollable failures when
65      restricted code invoked library code that must reassert interruption
66      to correctly propagate status when encountering some
67      <code>InterruptedExceptions</code>.
68      <li> The <code>destroy</code> method, which has never been implemented,
69      has finally been deprecated. This is just a spec change, reflecting
70      the fact that the reason it has never been implemented is that
71      it was undesirable and unworkable.
72    </ul>
73    
74  <h2>Timing</h2>  <h2>Timing</h2>
75    
76  Method <tt>nanoTime</tt> is added to {@link java.lang.System}. It  Method <code>nanoTime</code> is added to {@link java.lang.System}. It
77  provides a high-precision timing facility that is distinct from and  provides a high-precision timing facility that is distinct from and
78  uncoordinated with <tt>System.currentTimeMillis</tt>.  uncoordinated with <code>System.currentTimeMillis</code>.
79    
80  <h2>Removing ThreadLocals</h2>  <h2>Removing ThreadLocals</h2>
81    
# Line 98  designs. Line 86  designs.
86    
87    
88    <hr>    <hr>
   <address><A HREF="http://gee.cs.oswego.edu/dl">Doug Lea</A></address>  
89   </body>   </body>
90  </html>  </html>

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