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From: mishkin@apollo.HP.COM (Nathaniel Mishkin)
Newsgroups: comp.protocols.misc
Subject: Re: RPC Technologies
Message-ID: <1990Aug31.133311@apollo.HP.COM>
Date: 31 Aug 90 17:33:00 GMT
References: <1990Aug29.012657.1305@athena.mit.edu>
Sender: root@apollo.HP.COM
Reply-To: mishkin@apollo.HP.COM (Nathaniel Mishkin)
Organization: Hewlett-Packard Company - Cooperative Object Computing Operation
Lines: 29

In article <1990Aug29.012657.1305@athena.mit.edu>, pae@athena.mit.edu (Philip Earnhardt) writes:
>Just to make sure I understand you clearly, let me re-state what
>I think you've said:
>
>    While current NCS2.0 implementations are multi-threaded via the
>    POSIX PThreads package, there is no architectural restriction that
>    all ports of NCS2.0 must either use PThreads for their
>    implementation or even that all ports use multiple threads.

Correct.

>Finally, are the multiple threads of a NCS2.0 implementation cooperative -- do
>current implementations need a preemptive multi-threading package?

Preemption is required if servers are going to have threads (including
threads running some client's call) that are not going to voluntarily
yield (or terminate) within a relatively short period of time, e.g.,
30 seconds.  This is because the server has a thread created by the NCS
implementation that listens for "ping" messages from the client (which
is trying to determine the server's liveness).  If this thread doesn't
get a chance to run for long enough, the client will think the server
has died.  (Note that the client automatically reduces the ping frequency
during the duration of a single call.)

--
                    -- Nat Mishkin
                       Cooperative Object Computing Operation
                       Hewlett-Packard Company
                       mishkin@apollo.hp.com