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From "James Carman" <ja...@carmanconsulting.com>
Subject Re: codec - thread safe
Date Mon, 08 Oct 2007 17:58:28 GMT
Try using a ThreadLocal variable to store your Encoder/Decoder that
you need to be thread safe.

On 10/8/07, sebb <sebbaz@gmail.com> wrote:
> On 08/10/2007, Will Pugh <willpugh@sourcelabs.com> wrote:
> > David J. Biesack wrote:
> > >> Date: Mon, 8 Oct 2007 17:01:02 +0200
> > >> From: =?iso-8859-1?Q?J=F6rg_Schaible?= <Joerg.Schaible@Elsag-Solutions.com>
> > >>
> > >>
> > >>> The java.util.concurrent backport
> > >>> http://backport-jsr166.sourceforge.net/ runs on 1.3, for just this
> > >>> kind of use.
> > >>>
> > >> I know this, but I doubt that we wanna start to depend Apache common components
on it ;-)
> > >>
> > >
> > > Agreed; I, like you, was merely suggesting to what Commons consumers might
do to deal with non-threadsafe codecs.
> > >
> > >
> > Might seem like a silly question, but has anyone found anything that
> > looks like a threading issue in Codec?
>
> Yes -  QCodec has a public method that sets an instance variable (see
> my comments on CODEC-55).
>
> > The code is pretty simple.  I did a quick look through the code, and it
> > seemed like everything was pretty thread safe.  It looks like you should
> > be O.K. as long as:
> >    1)  You don't change the parameters to a codec while it's running,
> > e.g. changing charsets, etc.
>
> See above.
>
> Having said that, I think it would not be too difficult to fix the
> classes so that they are thread-safe. Most of the ones I looked at
> could even be made invariant.
>
> So their thread-safety would only depend on any external calls they
> made; this could presumably be fixed by providing synchronised
> versions as suggested earlier.
>
> >    2)  You should not use a MessageDigest returned by DigestUtils by
> > multiple threads.  This should be clear given the API (it's a SUN api)
> >
> > It also seems to me that the difference between code that you can trust
> > as being thread safe, and code you cannot trust as being thread safe has
> > a lot to do with whether it is tested for thread safety.  Seems to me
> > like another way of helping out here would be to build concurrency tests
> > for whichever APIs you are interested using on multiple threads.  Not
> > sure where we would put them yet, but seems like the only way to assure
> > thread-safety (especially if we could get someone to volunteer running
> > them on a big beefy multi-proc machine :).
>
> Indeed.
>
> > >> - Jörg
> > >>
> > >
> > >
> >
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>
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