[cvs] Annotation of /jsr166/src/main/intro.html

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4	dl	1.12	<title>JSR 166 Introduction.</title>
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8	dl	1.12	<h1>JSR 166 Introduction.</h1>
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10			by <a href="http://gee.cs.oswego.edu/dl">Doug Lea</a>
11			<p>
12
13	dl	1.16	This is the proposed final draft JSR166 specification. To check for
14			further updates, or join a mailing list discussing JSR-166, go to: <A
15	dl	1.9	HREF="http://altair.cs.oswego.edu/mailman/listinfo/concurrency-interest">
16	dl	1.14	http://altair.cs.oswego.edu/mailman/listinfo/concurrency-interest</A>.
17	dl	1.7
18	dl	1.14	<p><em>Note: The javadocs here includes some existing java.util
19			Collection interfaces and classes that are not part of the JSR-166
20			spec, but are included because JSR-166 methods implement or inherit
21			from their specifications.</em>
22	dl	1.9
23			<p> JSR-166 introduces package <tt>java.util.concurrent</tt>
24			containing utility classes commonly useful in concurrent
25			programming. Like package <tt>java.util</tt>, it includes a few small
26	dl	1.16	standardized extensible frameworks, as well as other classes that
27	dl	1.9	provide useful functionality and are otherwise tedious or difficult to
28			implement.
29
30			<p>JSR-166 focusses on breadth, providing critical functionality
31			useful across a wide range of concurrent programming styles and
32			applications, ranging from low-level atomic operations, to
33			customizable locks and synchronization aids, to various concurrent
34			data structures, to high-level execution agents including thread
35			pools. This diversity reflects the range of contexts in which
36			developers of concurrent programs have been found to require or desire
37			support not previously available in J2SE, which also keeping the
38	dl	1.16	resulting package small; providing only functionality that has been
39			found to be worthwhile to standardize.
40	dl	1.9
41			<p>Descriptions and brief motivations for the main components may be
42			found in the associated package documentation. JSR-166 also includes
43			a few changes and additions in packages outside of
44			java.util.concurrent. Here are brief descriptions.
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46			<h2>Queues</h2>
47
48	dl	1.3	A basic (nonblocking) {@link java.util.Queue} interface extending
49	dl	1.9	{@link java.util.Collection} is introduced into
50			<tt>java.util</tt>. Existing class {@link java.util.LinkedList} is
51			adapted to support Queue, and a new non-thread-safe {@link
52			java.util.PriorityQueue} is added.
53
54			<h2>Threads</h2>
55
56	dl	1.13	Three minor changes are introduced to the {@link java.lang.Thread}
57			class:
58			<ul>
59			<li> It now allows per-thread installation of handlers for uncaught
60			exceptions. Ths optionally disassociates handlers from ThreadGroups,
61			which has proven to be too inflexible. (Note that the combination of
62			features in JSR-166 make ThreadGroups even less likely to be used in
63			most programs. Perhaps they will eventually be deprecated.)
64
65			<li> Access checks are no longer required when a Thread interrupts
66			<em>itself</em>. The <tt>interrupt</tt> method is the only way to
67			re-assert a thread's interruption status (and in the case of
68			self-interruption has no other effect than this). The check here
69			previously caused unjustifiable and uncontrollable failures when
70			restricted code invoked library code that must reassert interruption
71			to correctly propagate status when encountering some
72			<tt>InterruptedExceptions</tt>.
73			<li> The <tt>destroy</tt> method, which has never been implemented,
74			has finally been deprecated. This is just a spec change, reflecting
75	dl	1.15	the fact that that the reason it has never been implemented is that
76	dl	1.13	it was undesirable and unworkable.
77			</ul>
78	dl	1.9
79			<h2>Timing</h2>
80
81			Method <tt>nanoTime</tt> is added to {@link java.lang.System}. It
82			provides a high-precision timing facility that is distinct from and
83			uncoordinated with <tt>System.currentTimeMillis</tt>.
84	dl	1.8
85			<h2>Removing ThreadLocals</h2>
86
87	dl	1.9	The {@link java.lang.ThreadLocal} class now supports a means to remove
88			a ThreadLocal, which is needed in some thread-pool and worker-thread
89	dl	1.2	designs.
90	dl	1.9
91
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