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Full Discussion: ps blocking
Top Forums UNIX for Advanced & Expert Users ps blocking Post 302436988 by steadyonabix on Tuesday 13th of July 2010 03:26:02 PM
Old 07-13-2010
ps blocking
Hi Folks


I have been debugging a script that is called every thirty seconds. Basically it is doing a ps, well two actually, one to file (read by the getline below) and the other into a pipe. The one into the pipe is: -

V_SYSVPS=/usr/sysv/bin/ps

Code:
$V_SYSVPS -p$PIDLIST -o$PSARGS 2>/dev/null | \
nawk -v tmpfile=$TMPFILE -v ta=$(vdate -t -d 197001010000.00 + $CMDTIME) \
                                  -v h=$V_HOSTNAME -v tr=$((COUNT * V_AUTO_MON_FREQUENCY)) -v argfield=$V_AUTO_MON_ARGFIELD \
                                  -v s="MON:1,psm,$V_AUTO_MON_START,$CMDTIME" \
                                  'BEGIN      {
                                                  while (getline < tmpfile)
                                                          l[$1] = $0
                                              }
                                              }'

The problem is that the sysv ps intermittently takes longer than 30 seconds to come back, I have echoed the date to file either side of it and it is definitely blocking on the write to the pipe. I have also trussed the nawk and it hangs on the read from the pipe.

I spotted that the getline does not check for EOF or close the file but it still blocks on the write to the pipe after I fixed it.

Trussing the ps itself shows it goes to the /dev directory for some reason which contains 29000 files and does a statx on each. However most of the time it deals with that in under 2 seconds.

Can anyone tell me if there is anything about the sysv ps that can explain this 30 delay? (Sometimes it takes 20 or so seconds but this completes in time)

Apparently this is using both ps commands because they could not get all the info they wanted from just the one version.
 

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mdbfontsize

mdbFontSize(5)							 The m17n Library						    mdbFontSize(5)

NAME

       mdbFontSize - Font Size

DESCRIPTION

       In some case, a font contains incorrect information about its size (typically in the case of a hacked TrueType font), which results in a
       bad text layout when such a font is used in combination with the other fonts. To overcome this problem, the m17n library loads information
       about font-size adjustment from the m17n database by the tags <font, resize>. The data is loaded as a plist of this format.

       FONT-SIZE-ADJUSTMENT ::= PER-FONT *

       PER-FONT ::= '(' FONT-SPEC ADJUST-RATIO ')'

       FONT-SPEC ::=
	   '(' [ FOUNDRY FAMILY
	      [ WEIGHT [ STYLE [ STRETCH [ ADSTYLE ]]]]]
	    REGISTRY ')'

       ADJUST-RATIO ::= INTEGER

       FONT-SPEC is to specify properties of a font. FOUNDRY to REGISTRY are symbols corresponding to Mfoundry to Mregistry property of a font.
       See m17nFont for the meaning of each property.

       ADJUST-RATIO is an integer number specifying by percentage how much the font-size must be adjusted. For instance, this PER-FONT:

	   ((devanagari-cdac) 150)

       instructs the font handler of the m17n library to open a font of 1.5 times bigger than a requested size on opening a font whose registry is
       'devanagari-cdac'.

COPYRIGHT

       Copyright (C) 2001 Information-technology Promotion Agency (IPA)
       Copyright (C) 2001-2011 National Institute of Advanced Industrial Science and Technology (AIST)
       Permission is granted to copy, distribute and/or modify this document under the terms of the GNU Free Documentation License
       <http://www.gnu.org/licenses/fdl.html>.

Version 1.6.2							    12 Jan 2011 						    mdbFontSize(5)
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