RE: How to continue monitoring file access (Was: Problem solved,

From: Brian MacLean <BMacLean_at_Homebid.com>
Date: Tue, 14 Nov 2000 16:57:07 -0700
Message-Id: <10680.122065@fatcity.com>

Even if you got fuser to loop you could miss processes. Per the man page for fuser:

NOTES

     Because fuser  works with a snapshot of the system image, it
     may  miss  processes that begin using a file while fuser  is
     running. Also, processes reported as using a file  may  have
     stopped  using  it  while  fuser  was running.

-----Original Message-----
From: yong huang [mailto:yong321_at_yahoo.com] Sent: Tuesday, November 14, 2000 4:05 PM To: Multiple recipients of list ORACLE-L Subject: Re: How to continue monitoring file access (Was: Problem solved, but WHY??? (Long))

Thanks, Jared.

gethrtime() is going to use a lot CPU, isn't it? What I really want is to capture fuser or lsof output absolutely without a single miss and it doesn't use much CPU. I hope there's a way to tell fuser that whenever a file (such as
sqlnet.ora) is read by a process, fuser writes the process info to a log file
(or a pipe we create) so we can tail -f that_log_file.

Yong Huang
yong321_at_yahoo.com

• Jared Still <jkstill_at_bcbso.com> wrote:
  > On Sat, 11 Nov 2000, yong huang wrote:
  >
  > > I know the command "fuser somefile" reports what processes are accessing
  > > somefile. Is there a way to continue monitoring this so it won't exit at
  > the
  > > initial detection? I'd like to see the output like "tail -f
  somelogfile". I
  > > don't think wrapping this in a shell infinite loop is an option because
  (1)
  > if
  > > you don't use sleep in the loop, it hogs CPU; (2) if you do, there's too
  > much
  > > gap between two fuser calls.
  > >
  > > Yong Huang
  > > yong321_at_yahoo.com
  > >
  >
  > 1 second between calls to fuser via 'sleep 1' seems reasonable.
  >
  > If you need more granularity, and your system supports high
  > resolution timers, here's an example of one that will time
  > in nano-seconds.
  >
  >
  > #include <sys/time.h>
  > #include <stdio.h>
  >
  > void main ( int argc, char *argv[] ) {
  > hrtime_t start, end;
  > int i;
  >
  > i = argv[1] == NULL ? 200000000 : atoi(argv[1]);
  >
  > printf("Nanoseconds: %i nsec\n", i);
  >
  > start = gethrtime();
  >
  > printf("Start: %lld nsec\n", start);
  >
  > for (;;) {
  > end = gethrtime();
  > if ( ( end - start ) >= i ) { break; }
  > }
  >
  > printf("End: %lld nsec\n", end);
  >
  >
  > }
  >
  >
  >
  > Jared Still
  > Certified Oracle DBA and Part Time Perl Evangelist ;-)
  > Regence BlueCross BlueShield of Oregon
  > jkstill_at_bcbso.com - Work - preferred address
  > jkstill_at_teleport.com - private
  >
  >
  

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Author: yong huang
  INET: yong321_at_yahoo.com

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Received on Tue Nov 14 2000 - 17:57:07 CST