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From: Ted Dennison<dennison@telepath.com>
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 <slrn9slt9m.i2.lutz@taranis.iks-jena.de> <3BCC01B1.18C18C98@free.fr>
 <3BCC6CB7.20BAA30D@boeing.com> <3BCD2EC3.3B3C4498@free.fr>
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In article <3BCD2EC3.3B3C4498@free.fr>, Jean-Marc Bourguet says...
>
>4) whatever you do -- trying to modify the datastructure simultaneously
>via iterators from different tasks -- is save.
>
>>From my experience,
>  * level 4 is useless because you still need synchronisation
>    for other reasons when its whole generality is needed.  Achieving it
>    has a major performance impact (every operation has to be
>protected).

But your "level 4" is exactly what is needed for the "gender-bender"
server-to-server queue we were referring to. This is a *quite* common need. Its
come up in every multitasking Ada app I've ever written of at least moderate
complexity. Your assertion is quite wrong too. When used as I described, it is
the *only* communication the two server tasks need. In fact, it is the only safe
communication method they can have. 

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