I have thought that pattern would fix the problem also but I have
never seen anyone mention it before.
On 12/2/05, Trenton D. Adams <[EMAIL PROTECTED]> wrote:
> Actually, a co-worker and I just came up with a possible solution.
>
> public static Object getInstance()
> {
> if (instance == null)
> createInstance();
>
> return instance;
> }
>
> private static synchronized void createInstance()
> {
> if (instance == null)
> instance = new Object();
> }
>
> So, we end up having the required synchronized method, but without the
> normal performance hit.
>
> Ok, I'm done now. :)
>
> Curt Arnold wrote:
> >
> > On Dec 1, 2005, at 8:39 PM, Trenton D. Adams wrote:
> >
> >>
> >> As a general rule, singleton methods should not be synchronized for
> >> performance reasons. If this method is only called once in awhile,
> >> no big deal. But, if it's called regularly, then it can be a really
> >> big performance problem. Does the log4j project have coding
> >> standards for such things?
> >>
> >> This particular singleton method should check the
> >> "_defaultLogMonitor" for null first. If it is not null, it should
> >> return it. If it is null, it should synchronize on some object,
> >> perhaps LF5Appender.class. Then it should check it for null again.
> >> If it is not null, it should return it. If it is null, it should
> >> construct it.
> >>
> >
> > That idiom is not thread-safe but the explanation is too complicated to
> > go into here. See "The Double-Checked Locking is Broken" Declaration
> > (http://www.cs.umd.edu/~pugh/java/memoryModel/
> > DoubleCheckedLocking.html). Also covered on pg 193 of "Effective Java"
> > which I highly recommend.
> >
> > ---------------------------------------------------------------------
> > To unsubscribe, e-mail: [EMAIL PROTECTED]
> > For additional commands, e-mail: [EMAIL PROTECTED]
> >
>
>
> --
> Trenton D. Adams
> Systems Analyst/Web Software Engineer
> Navy Penguins at your service!
> Athabasca University
> (780) 675-6195
> :wq!
>
> __
> This communication is intended for the use of the recipient to whom it
> is addressed, and may contain confidential, personal, and or privileged
> information. Please contact us immediately if you are not the intended
> recipient of this communication, and do not copy, distribute, or take
> action relying on it. Any communications received in error, or
> subsequent reply, should be deleted or destroyed.
> ---
>
> ---------------------------------------------------------------------
> To unsubscribe, e-mail: [EMAIL PROTECTED]
> For additional commands, e-mail: [EMAIL PROTECTED]
>
>
--
James Stauffer
Are you good? Take the test at http://www.livingwaters.com/good/
---------------------------------------------------------------------
To unsubscribe, e-mail: [EMAIL PROTECTED]
For additional commands, e-mail: [EMAIL PROTECTED]
