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59 lines
2.4 KiB
XML
59 lines
2.4 KiB
XML
<?xml version="1.0" encoding="utf-8"?>
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<!DOCTYPE book [
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<!ENTITY % eclent SYSTEM "ecl.ent">
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%eclent;
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]>
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<book xmlns="http://docbook.org/ns/docbook" version="5.0" xml:lang="en">
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<chapter xml:id="ext.mp">
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<title>Multithreading</title>
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<section xml:id="ext.mp.threads">
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<title>Tasks, threads or processes</title>
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<para>On most platforms, &ECL; supports native multithreading. That means
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there can be several tasks executing lisp code on parallel and sharing
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memory, variables and files. The interface for multitasking in &ECL;, like
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those of most other implementations, is based on a set of functions and
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types that resemble the multiprocessing capabilities of old Lisp Machines.
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</para>
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<para>This backward compatibility is why tasks or threads are called
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"processes". However, they should not be confused with operating system
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processes, which are made of programs running in separate contexts and
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without access to each other's memory.</para>
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<para>The implementation of threads in &ECL; is purely native and based on
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Posix Threads wherever avaiable. The use of native threads has
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advantanges. For instance, they allow for non-blocking file operations,
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so that while one task is reading a file, a different one is performing
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a computation.</para>
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<para>As mentioned above, tasks share the same memory, as well as the set of
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open files and sockets. This manifests on two features. First of all,
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different tasks can operate on the same lisp objects, reading and writing
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their slots, or manipulating the same arrays. Second, while threads share
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global variables, constants and function definitions they can also have
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thread-local bindings to special variables that are not seen by other
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tasks.</para>
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<para>The fact that different tasks have access to the same set of data
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allows both for flexibility and a greater risk. In order to control access
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to different resources, &ECL; provides the user with locks, as explained in
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the next section.</para>
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</section>
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<xi:include xmlns:xi="http://www.w3.org/2001/XInclude" href="ref_mp.xmlf" xpointer="ext.mp.dict"/>
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</chapter>
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</book>
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<!-- Keep this comment at the end of the file
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Local variables:
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mode: nxml
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sgml-parent-document: "ecl.xml"
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sgml-indent-step: 1
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nxml-child-indent: 1
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nxml-outline-child-indent: 1
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fill-column: 79
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End:
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-->
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