Re: On the issue of low memory situations

Date: Sun Mar 19 2000 - 12:52:53 EST

David Weinehall wrote:

>AIX implements something akin to this. When memory is running low, it
>sends SIGDANGER to all processes. Those who doesn't trap it, dies. Those
>who trap it can shut down gracefully or, if they are important daemons,
>stay alive.

     Actually, the default disposition for SIGDANGER is to ignore it.
SIGDANGER can be caught, the idea being that they can try to log the fact,
free memory or at least forego anything really memory-intensive in the near
future. 'man 3 psdanger' on AIX show how to query the paging space on the
system, as well as its proximity to the SIGDANGER and SIGKILL thresholds.
I can see advantages to David's way, though--programs written without much
care (buggy, bloated, memory hogs) have probably overlooked SIGDANGER and
will be self-selected for reaping when memory gets tight.

     Justin T. Fries
     Raleigh, North Carolina

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