Re: Atomic thread safe integer increment..
Thomas Kellerer wrote:
On 14.09.2006 14:04 lordy wrote:
Hi, I want to keep a running 'int' total across threads but without the
'synchronized' overhead. (This total will be spinning pretty fast).
I guess the most performant(?) option is to maintain separate totals and
combine them at report time?
The perfomance "penalty" of a synchronized block is relatively small.
I think there is an article on DeveloperWorks that de-mystifies the
common believe that synchronize will make things slower. If I recall the
article correctly this was true for JDK up to 1.3 but starting with 1.4
(or 1.5 not 100% sure about that) the overhead is so small that it does
not justify the effort to avoid it.
If it's a contended lock, particularly on a multicore machine, it could
well be a problem. Having said that, in this case the lock shouldn't be
held for very long.
A local value for each thread should be much faster. Alternatively, if
you can live with an inaccurate variable, just use volatile (I think
that works in 1.4).
Tom Hawtin
--
Unemployed English Java programmer
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