Subj : Re: double-checked locking in C
To   : comp.programming.threads
From : David Schwartz
Date : Sat Jul 09 2005 02:41 pm


"Joe Seigh" <jseigh_01@xemaps.com> wrote in message 
news:PamdnUOYDe03SVLfRVn-1w@comcast.com...

> Now take DCL (the OT. surprise!).  The problem is that apparently so far, 
> no one has
> formally defined it (is is a valid synchronization technique after all). 
> Without that,
> you can't demand that someone show formally that their implementation 
> works.  All they
> have to do is tell you that they're run their DCL compliance testcase a 
> zillion times
> and it appears to work.  And they can ignore all your examples of how 
> things *could*
> go wrong much to your and everyone else's exasperation.

    I agree that people do this, and I certainly agree with your description 
of how I feel about it. Their code may not work on the next compiler, the 
next CPU, or the next version of the operating system.

    The purpose of the testcase is to validate the *implementation*, that 
is, the particular code on the particular platform with the particular 
compiler and the particular library. Compliance with a test case is some 
assurance that anything dumb you didn't won't bite you on that particular 
combination. It does not make sure you didn't do something dumb.

    DS

.