Path: utzoo!attcan!uunet!cs.utexas.edu!tut.cis.ohio-state.edu!bloom-beacon!gatech!ncar!dinl!noren
From: noren@dinl.uucp (Charles Noren)
Newsgroups: comp.unix.questions
Subject: Re: Insufficient Resource Error on msgsnd Call
Keywords: msgsnd, msgrcv, Ingres, UNIX, System V, message queues, Sun, SunOS4.0
Message-ID: <1029@dinl.mmc.UUCP>
Date: 25 May 89 14:13:41 GMT
References: <1023@dinl.mmc.UUCP> <8340@june.cs.washington.edu>
Reply-To: noren@dinl.UUCP (Chuck Noren)
Organization: Martin Marietta I&CS, Denver CO.
Lines: 30

In article <8340@june.cs.washington.edu> ka@june.cs.washington.edu (Kenneth Almquist) writes:
]>    +--------+                +--------+                +--------+
]>    |        |      +-----+   |        |      +-----+   |        |
]>    | Proc A |---->>| Q 1 |-->| Proc B |---->>| Q 2 |-->| Proc C |
]>    |        |      +-----+   |        |      +-----+   |        |
]>    +--------+                +--------+                +--------+
]
]On the other hand, you write:
]
]> Queue 2 looks empty because Process C is blocking on it (using
]> msgsnd with IPC_WAIT) ...
]> reading Queue 2 several times breaks the log jam and the system runs
           ^^^^^^^
]> for a while ...
]
]If you can read messages off of queue 2 while process C is blocked on a
]read, that indicates a kernel bug.  Probably the msgsnd system call is
]failing to call wakeup for some reason.
]				Kenneth Almquist

Oops, I meant to say Queue 1.  Several have caught me on this one.
I'm glad to see all of the good responses in spite of mis-stating
some of the information.

-- 
Chuck Noren
NET:     ncar!dinl!noren
US-MAIL: Martin Marietta I&CS, MS XL8058, P.O. Box 1260,
         Denver, CO 80201-1260
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