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From Chuck Murcko <>
Subject Re: my whack at better status output
Date Mon, 29 Apr 1996 17:01:01 GMT
Robert S. Thau liltingly intones:
>   Even copying from shared memory isn't totally safe without a semaphore
>   of some kind, surely?
> Depends what you mean by "safe".  In this particular instance, the only
> risk is that the final output may reflect the state of different scoreboard
> entries at slightly different instances in time.  Personally, I don't feel
> that this is of very much consequence --- after all, 'ps' has behaved
> this way from time immemorial, and that's never bothered me much either.
Well, writing and reading from shared memory gets really unsafe w/o
semaphores, or even a shm manager in extreme cases.

> (The note to which I was responding pointed out that unless you make a
> copy, and do summary statistics off that, Brian's changes may result
> in a summary which disagrees slightly with what you'd get by actually
> summarizing the detail information in the same status report.  Doing
> both reports off the same scoreboard snapshot makes sure that the
> output is in synch with itself, though again, it wouldn't bug me over
> much if it weren't).
Not to mention that it saves making a second read on the scoreboard itself
to deal with the new formatting.

Chuck Murcko	N2K Inc.	Wayne PA
And now, on a lighter note:
Bizarreness is the essence of the exotic

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