Re: keep a java program open

["Simon Coulter" <shc@xxxxxxxxxxxxxxxxx>]

Hello David,

You wrote:
>I always believed the manuals that said data queues were the fastest
>means of interprocess communication and were extremely lightweight.

They are fast -- faster than the alternatives of message queue or file --
and user queues are faster still.  The major problem with data queues
occurs when they are keyed AND you fill them with data before starting the
process that fetches the data (may also occur when entries arrive on the
queue faster than the queue reader can process them).

The reason is simple.  On RISC AS/400 a keyed queue is not sorted when
entries are added (as happened on IMPI) but rather sorted when a dequeue
operation is performed.  The sort is not very efficient (On**2 last time I
looked) and I don't believe it has changed.

So changing from keyed to sequential as you did would certainly make an
improvement but I would expect a major benefit only if you were filling the
queue before processing the entries.

Regards,
Simon Coulter.

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