Programming Ruby

The Pragmatic Programmer's Guide

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class ThreadGroup
Parent: Object
Version: 1.6


new add list

ThreadGroup provides a means of keeping track of a number of threads as a group. A Thread can belong to only one ThreadGroup at a time; adding a thread to a new group will remove it from any previous group.

Newly created threads belong to the same group as the thread from which they were created.
Default Default thread group.

class methods
new -> thgrp

Returns a newly created ThreadGroup. The group is initially empty.

instance methods
add thgrp.add( aThread ) -> thgrp

Adds the given thread to this group, removing it from any other group to which it may have previously belonged.

puts "Initial group is #{ThreadGroup::Default.list}"
tg =
t1 = { sleep 10 }
t2 = { sleep 10 }
puts "t1 is #{t1}"
puts "t2 is #{t2}"
tg.add( t1 )
puts "Initial group now #{ThreadGroup::Default.list}"
puts "tg group now #{tg.list}"
Initial group is #<Thread:0x401be5c8>
t1 is #<Thread:0x401b5428>
t2 is #<Thread:0x401b53d8>
Initial group now #<Thread:0x401b53d8>#<Thread:0x401be5c8>
tg group now #<Thread:0x401b5428>

list thgrp.list -> anArray

Returns an array of all existing Thread objects that belong to this group.

ThreadGroup::Default.list [#<Thread:0x401be5c8 run>]

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Extracted from the book "Programming Ruby - The Pragmatic Programmer's Guide"
Copyright © 2001 by Addison Wesley Longman, Inc. This material may be distributed only subject to the terms and conditions set forth in the Open Publication License, v1.0 or later (the latest version is presently available at

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