>The reputation of Bill Pugh is quite high - enough so that I would be
>nclined to take his statements on this subject as beyond challenge.
As well you should. And many very smart people have signed his
declaration, including Doug Lea.
>Upon careful reading of the link mentioned in this thread, I came across
>the following:
>
> It will work for 32-bit primitive values
>
> Although the double-checked locking idiom cannot be used for references
> to objects, it can work for 32-bit primitive values (e.g., int's or
> float's). Note that it does not work for long's or double's, since
> unsynchronized reads/writes of 64-bit primitives are not guaranteed to
> be atomic.
This statement is true, but very easy to misinterpret; be careful. There
have been many attempts to "fix" DCL by trying to exploit that; they all
fail.
>Based on this, it would seem to me that the code snippet staring with "if
>(_jspx_inited == false) {" is safe. Worst case, change _jspx_inited from
>boolean to int.
Seems that way, but its not. You can't use this to make an end-run around
the problem in the general case. If jspx_init() creates any objects,
you've gotta synchronize, plain and simple. If jspx_init() calculates
multiple primitive values, which can obtained through any other means than
its return value, you've gotta synchronize.
--
Brian Goetz
Quiotix Corporation
[EMAIL PROTECTED] Tel: 650-843-1300 Fax: 650-324-8032
http://www.quiotix.com
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