Re: Tradeoffs between ConcurrentLinkingQueue and LinkedBlockingQueue

From:

Lew <noone@lewscanon.com>

Newsgroups:

comp.lang.java.programmer

Date:

Wed, 29 Sep 2010 09:23:10 -0400

Message-ID:

<i7vej3$g50$1@news.albasani.net>

Sebastian Millies wrote:

static Queue queue = new ConcurrentLinkedQueue<Request>();

NEVER mix raw and generic types!

schrieb Lew:

While we're waiting for that answer, I'll point out that you likely do
not want static member variables for these. Naturally I can't be sure,
not having seen anything of your code but snippets, but given the rarity
of use cases for 'static' here, snippets containing 'static' were a red
flag.

Sebastian Millies wrote:

could you explain why you think so? I intend to have one dedicated

I know so. 'static' members are unique within the class. At best this
creates a bottleneck for things that are heavily used, at worst wrong results.

consumer thread that must be accessible to all producers in order to
unpark it. So I would think it would have to be either a static variable
or an instance variable in a singleton class. Similarly for the queue.
Would there be any disadvantage in using a static variable?

Yes, there very well would be. With a 'static' variable you only get one.
With instance or local variables you contain scope and lifetime to exactly
what's needed.

First, observe that 'static' is not necessary. The question isn't "Why not
'static'?" but "Why 'static'?" The burden of proof is on the use of 'static'.

A variable simply has to be in scope for all threads (and 'final', if local)
to be shared between threads.

Instance and local variables are easier to control than 'static'.

--
Lew