Concurrent Programming in Java
© 1996-1999 Doug Lea
Updates for J2SE 5.0 (aka 1.5, Tiger)
Someday, I hope there will be a third edition of this book. But in the
mean time, here is a quick guide to how language and library updates
affect coverage in the second edition:
- Package java.util.concurrent (JSR166) includes
versions of the utilities described in the book, plus some
others. Some of the class names and APIs are different than book
versions, but should be easy to figure out.
- Section 220.127.116.11 says that arranging uncaughtException handlers
is one of the few reasons to use ThreadGroup. Now this can be done
within class Thread itself, leaving one fewer reason to use
- Section 2.2.7.x on the Memory Model doesn't provide current
details of the JSR133 spec revision. (The basic ideas still apply
though.) One change that commonly arises in practice is that Section
18.104.22.168 and 22.214.171.124 should say that reading a volatile reference
makes visible other changes to the referred object by the thread
writing the reference. In particular, double-check idioms work in
the expected way when references are declared volatile.
- Section 2.2.3 only implicitly mentions weakly-consistent
iterators, which are used extensively in java.util.concurrent
collections. They differ from fast-fail in that they promise to be
thread safe, but don't promise whether you will see any updates made
to the collection since the iterator was constructed (e.g., you
might see an added element, or you might not).
- Section 126.96.36.199 on Optimistic Updates takes on added importance
now that Java directly supports atomic updates (in package
java.util.concurrent.atomic). This greatly expands the range of
application of the basic ideas in this section, enabling
construction of efficient nonblocking algorithms and data structures
(some of which appear in java.util.concurrent).
- In Section 188.8.131.52, the precaution of adding an extra notify()
on interruption is no longer necessary (it doesn't hurt though)
because of spec clarifications made in JSR133. Additionally,
several of the twisty constructions in Sections 3.2.3 and 3.7
can be avoided by using utilities in package java.util.concurrent.locks.
- The polling discussion and examples in Section 4.1.5 can
use java.nio rather than the illustrated emulations.
- The Executor framework in java.util.concurrent includes
more functionality than indicated in Section 4.1, and
includes versions of Callables and Futures that are simpler to use than
stated in Section 4.3.