Some of these are referred to as being "bounded" while others are "unbounded". I don't understand the meanings behind these terms, which makes it hard to make a choice as to which one is most suitable for my project. Could someone please explain, in laymans terms, what the difference is between a bounded queue and an unbounded queue?
My project will involve several threads running, each of which will access and insert into the queue an EMessage object, which is essentially an email message with subject line (two Strings in other words). The queue will then release each EMessage, one at a time, to another class that will perform the actual processing of the email. Hope this helps. Perhaps with this description you can recommend the appropriate type queue class to use?
Alan [ December 12, 2006: Message edited by: Alan Shiers ]
Blocking Queue doc says it's optionally "capacity bounded" meaning that you can only put a specified number of items in the queue. If you try to put more, the put operation blocks until another thread takes something out and makes room. Exercise for the original poster: Which other ones said they were bounded? Does that definition fit them, too?
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So, I believe I understand now. Bounded simply means that the queue has a specific capacity that cannot be exceeded. Unbounded is one who capacity can expand, at least as far as memory consumption will permit.
So, I believe I would be looking for an unbounded queue. Since I'm not too concerned about the growing capacity of the queue, and since the queue will be accessed by multiple threads, my best choice is probably ConcurrentLinkedQueue.
Abhineet Kapil wrote:which might mean, that poll operation will still hold as blocking operation for unbounded blocking queue.
And what would you have it do otherwise?
Joanne's basically explained it for you, but think about what "unbounded" means. The Queue can't return a value it doesn't have, so it needs some mechanism to say "I don't have a value for you".
Personally, I prefer blocking, because otherwise you usually need to write code which simply "buzzes" until it can provide a value - which is, logically, the same thing. And blocking is generally preferable (and less CPU-intensive) unless you have a specific reason to "buzz".
Or, of course, do something else.
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