Channels ▼

JVM Languages

Multithreading, Java, & OSGi

Source Code Accompanies This Article. Download It Now.

Interrupted Exceptions

Prior to this multithreading exercise, InterruptedException had always been a bit of a mystery to me. Was it really needed? Why? What should I do with it? Sample code frequently ignores it. Even Doug Lea didn't really seem to know what to do with it in Concurrent Programming in Java (Addison-Wesley, 2000).

ThreadManager gives a clear answer to these questions: InterruptedException must be obeyed—not ignored. The exception is thrown when a thread should exit posthaste. Ignoring it is almost certainly the wrong thing to do. Certainly ThreadManager won't work properly if you do. Proper operation of ThreadManager requires that threads exit when requested. If they don't, calls to stopAll() won't return.

The same applies to other exceptions, such as IOExceptions, which might indicate interruptions. These cases have always seemed more obvious to me; after all, there is often little one can do after receiving an exception on a socket. InterruptedException has always carried that temptation to try again.

Consistent with this advice, ThreadManager itself will break out of a call to stopAll() if it gets interrupted. Is this the right thing to do? It would seem to depend on the situation—something only the caller can know. When handling exceptions, deferring up the call stack generally seems like the right solution.

Related Reading

More Insights

Currently we allow the following HTML tags in comments:

Single tags

These tags can be used alone and don't need an ending tag.

<br> Defines a single line break

<hr> Defines a horizontal line

Matching tags

These require an ending tag - e.g. <i>italic text</i>

<a> Defines an anchor

<b> Defines bold text

<big> Defines big text

<blockquote> Defines a long quotation

<caption> Defines a table caption

<cite> Defines a citation

<code> Defines computer code text

<em> Defines emphasized text

<fieldset> Defines a border around elements in a form

<h1> This is heading 1

<h2> This is heading 2

<h3> This is heading 3

<h4> This is heading 4

<h5> This is heading 5

<h6> This is heading 6

<i> Defines italic text

<p> Defines a paragraph

<pre> Defines preformatted text

<q> Defines a short quotation

<samp> Defines sample computer code text

<small> Defines small text

<span> Defines a section in a document

<s> Defines strikethrough text

<strike> Defines strikethrough text

<strong> Defines strong text

<sub> Defines subscripted text

<sup> Defines superscripted text

<u> Defines underlined text

Dr. Dobb's encourages readers to engage in spirited, healthy debate, including taking us to task. However, Dr. Dobb's moderates all comments posted to our site, and reserves the right to modify or remove any content that it determines to be derogatory, offensive, inflammatory, vulgar, irrelevant/off-topic, racist or obvious marketing or spam. Dr. Dobb's further reserves the right to disable the profile of any commenter participating in said activities.

Disqus Tips To upload an avatar photo, first complete your Disqus profile. | View the list of supported HTML tags you can use to style comments. | Please read our commenting policy.