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Article #777

Re: Is applying ulimit to pipes a bug?

#777
From: Daniel R. Levy
Date: Tue, 17 May 1988 18:19
28 lines
2154 bytes
In article <242@twg-ap.UUCP>, dwh@twg-ap.UUCP (Dave Hamaker) writes:
# I find myself often needing/wanting to put filters before and/or after raw
# devices and network connections.  Often, the volume of data involved exceeds
# the ulimit file size controls.  If I don't raise the ulimit, the pipes fail.
# This doesn't make sense to me, as pipes do not accumulate resources in the
# same kind of way as disk files: an out-of-control disk file can use up all
# the disk space; an out-of-control pipe consumes only renewable resources.
# The ulimit documentation is inclusive on the matter; in fact, it sounds
# confused.  If you ask me, I smell a bug of omission; the pipe type just rode
# along with the file type during ulimit implementation, without much thought
# about it.
# The Wollongong Group

What VERSION of System V are you using, on what machine?  The only pipe-related
ulimit problem I've noticed here (ttrdc ttrdc 2.0v3 1208 3B-20S) is if I make
the ulimit so ridiculously small (like 9) that the ulimit is smaller then the
pipe's buffering capacity (5120 bytes).  In this event a write larger than the
ulimit indeed fails with EFBIG.  I suppose you could call that a bug, albeit
a rather unlikely bug.  If I make the ulimit larger than the pipe's buffering
capacity (even 11) then I can call write() with as much as I please (1
megabyte? no problem, it works) to a pipe.

(I just tried it again on a 3B2, SVR3.1.  Same results.)
-- 
|------------Dan Levy------------|  Path: ihnp4,<most AT&T machines>!ttrdc!levy
|              AT&T              |  Weinberg's Principle:  An expert is a
|       Data Systems Group       |  person who avoids the small errors while
|--------Skokie, Illinois--------|  sweeping on to the grand fallacy.
Technical Details
Message-ID: <2673@ttrdc.UUCP>
Path: arc1-ca.pugleaf.net!utzoo!utgpu!water!watmath!clyde!att!ttrdc!levy
References: <242@twg-ap.UUCP>

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Path: arc1-ca.pugleaf.net!utzoo!utgpu!water!watmath!clyde!att!ttrdc!levy
From: levy@ttrdc.UUCP (Daniel R. Levy)
Newsgroups: comp.bugs.sys5
Subject: Re: Is applying ulimit to pipes a bug?
Summary: what version of system V?
Keywords: ulimit pipe filesystem
Message-ID: <2673@ttrdc.UUCP>
Date: 17 May 88 18:19:49 GMT
References: <242@twg-ap.UUCP>
Organization: AT&T, Skokie, IL
Lines: 28