Re: simultaneous function calls

From:

Lew <lew@lewscanon.com>

Newsgroups:

comp.lang.java.programmer

Date:

Thu, 06 Sep 2007 10:00:49 -0400

Message-ID:

<jJednR5uioyOlX3bnZ2dnUVZ_qiinZ2d@comcast.com>

korcs wrote:

Thanks for your replies!

I found myself a really good tutorial for java threads as well.

http://www.freejavaguide.com/java-threads-tutorial.pdf

While reading your comments and the suggested tutorials, I was
wondering whether my problem was really a synchronization problem.

Maybe I did not understand everything quite well, but it seems to me,
that synchronization is needed in situations where 2 or more threads
could WRITE(!) global variables simultaneously and make data
inconsistent.

So it means that if a method, used maybe simultaneously by multiple
threads causes only a READ action on program data, then
synchronization is not necessary (not needed and would cause only an
unneccesary overhead).

False if the datum in question is non-immutable and non-final.

Is it correct or did I miss something?

You missed something.

If more than one thread /accesses/ a variable, read or write, you must
synchronize. The "synchronized" keyword is not the only way to synchronize.

Compile-time constants and static final immutable objects are synchronized by
the rules of when such things are created. Thus read-only access can avoid
"synchronized" in such cases, but it doesn't avoid synchronization.

--
Lew