Idea for alternative MRTG scheduler

Steve Shipway <[email protected]> Thu, 16 Dec 2010 22:36:38 +0000
Newsgroups gmane.network.mrtg.devel
Message-ID <28E447343A85354483BCF7C3E9D5EAA5149F23C9@uxcn10-1.UoA.auckland.ac.nz>
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Here's an idea.

Currently, MRTG will process all Targets until there are none left, using u=
p all the available threads, and then sleep until the next polling cycle.

This can be problematic if you configure more targets, or there is an outag=
e, and suddenly you do not have enough threads to process everything in the=
 5min window.  Also, it results in a large burst of activity at the start o=
f the window followed by silence.

So, how about this - MRTG already knows how many targets there are, and the=
 interval.  It calculates x=3D(interval/#targets)x0.9 (the 0.9 is to allow =
time for the final checks to complete) and then kicks off a new Target to p=
rocess every x seconds, starting a new thread if required (possibly up to a=
 specified upper limit).  This would possibly end up with each thread proce=
ssing a single target and then exiting, with the master starting a new thre=
ad per Target.

I think this may be how the Nagios check scheduler works?  It would certain=
ly solve the problems of (a) uneven CPU usage and (b) running out of window=
 time when you add more targets but not more threads.  The drawback is that=
, of course, you need to have sufficient CPU/memory to handle the potential=
ly large number of threads that could result.

Since Tobi is currently in a coding mood, I thought it best to get the sugg=
estions in quick :)

Steve

________________________________
Steve Shipway
ITS Unix Services Design Lead
University of Auckland, New Zealand
Floor 1, 58 Symonds Street, Auckland
Phone: +64 (0)9 3737599 ext 86487
DDI: +64 (0)9 924 6487
Mobile: +64 (0)21 753 189
Email: [email protected]<mailto:[email protected]>
P Please consider the environment before printing this e-mail



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</o:shapelayout></xml><![endif]--></head><body lang=3DEN-NZ link=3Dblue vli=
nk=3Dpurple><div class=3DWordSection1><p class=3DMsoNormal>Here&#8217;s an =
idea.<o:p></o:p></p><p class=3DMsoNormal><o:p>&nbsp;</o:p></p><p class=3DMs=
oNormal>Currently, MRTG will process all Targets until there are none left,=
 using up all the available threads, and then sleep until the next polling =
cycle.<o:p></o:p></p><p class=3DMsoNormal><o:p>&nbsp;</o:p></p><p class=3DM=
soNormal>This can be problematic if you configure more targets, or there is=
 an outage, and suddenly you do not have enough threads to process everythi=
ng in the 5min window.&nbsp; Also, it results in a large burst of activity =
at the start of the window followed by silence.<o:p></o:p></p><p class=3DMs=
oNormal><o:p>&nbsp;</o:p></p><p class=3DMsoNormal>So, how about this &#8211=
; MRTG already knows how many targets there are, and the interval.&nbsp; It=
 calculates x=3D(interval/#targets)x0.9 (the 0.9 is to allow time for the f=
inal checks to complete) and then kicks off a new Target to process every x=
 seconds, starting a new thread if required (possibly up to a specified upp=
er limit).&nbsp; This would possibly end up with each thread processing a s=
ingle target and then exiting, with the master starting a new thread per Ta=
rget.<o:p></o:p></p><p class=3DMsoNormal><o:p>&nbsp;</o:p></p><p class=3DMs=
oNormal>I think this may be how the Nagios check scheduler works?&nbsp; It =
would certainly solve the problems of (a) uneven CPU usage and (b) running =
out of window time when you add more targets but not more threads.&nbsp; Th=
e drawback is that, of course, you need to have sufficient CPU/memory to ha=
ndle the potentially large number of threads that could result. <o:p></o:p>=
</p><p class=3DMsoNormal><o:p>&nbsp;</o:p></p><p class=3DMsoNormal>Since To=
bi is currently in a coding mood, I thought it best to get the suggestions =
in quick <span style=3D'font-family:Wingdings'>J</span><o:p></o:p></p><p cl=
ass=3DMsoNormal><o:p>&nbsp;</o:p></p><p class=3DMsoNormal>Steve<o:p></o:p><=
/p><p class=3DMsoNormal><o:p>&nbsp;</o:p></p><div class=3DMsoNormal align=
=3Dcenter style=3D'text-align:center'><span lang=3DEN-US><hr size=3D2 width=
=3D"100%" align=3Dcenter></span></div><p class=3DMsoNormal><b>Steve Shipway=
<o:p></o:p></b></p><p class=3DMsoNormal><span style=3D'font-size:10.0pt'>IT=
S Unix Services Design Lead<o:p></o:p></span></p><p class=3DMsoNormal><span=
 style=3D'font-size:10.0pt'>University of Auckland, New Zealand<o:p></o:p><=
/span></p><p class=3DMsoNormal><span style=3D'font-size:10.0pt'>Floor 1, 58=
 Symonds Street, Auckland<o:p></o:p></span></p><p class=3DMsoNormal><i><spa=
n style=3D'font-size:10.0pt;color:#595959'>Phone: +64 (0)9 3737599 ext 8648=
7<o:p></o:p></span></i></p><p class=3DMsoNormal><i><span style=3D'font-size=
:10.0pt;color:#595959'>DDI: +64 (0)9 924 6487<o:p></o:p></span></i></p><p c=
lass=3DMsoNormal><i><span style=3D'font-size:10.0pt;color:#595959'>Mobile: =
+64 (0)21 753 189<o:p></o:p></span></i></p><p class=3DMsoNormal><i><span st=
yle=3D'font-size:10.0pt;color:#595959'>Email: <a href=3D"mailto:s.shipway@a=
uckland.ac.nz"><span style=3D'color:#595959'>[email protected]</span=
></a><o:p></o:p></span></i></p><p class=3DMsoNormal><span lang=3DEN-GB styl=
e=3D'font-size:18.0pt;font-family:Webdings;color:green'>P</span><span lang=
=3DEN-GB style=3D'color:blue'> </span><span lang=3DEN-GB style=3D'font-size=
:10.0pt;font-family:"Arial Narrow","sans-serif";color:green'>Please conside=
r the environment before printing this e-mail</span><span lang=3DEN-GB styl=
e=3D'color:blue'> </span><span lang=3DEN-GB style=3D'font-size:7.5pt;font-f=
amily:"Verdana","sans-serif";color:navy'><o:p></o:p></span></p><p class=3DM=
soNormal><i><span style=3D'font-size:10.0pt'><o:p>&nbsp;</o:p></span></i></=
p><p class=3DMsoNormal><o:p>&nbsp;</o:p></p></div></body></html>=

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