No subject

Thu Nov 6 15:12:30 EST 2008

with
message=20
delivery when they have changed the clock, via settimeofday and even =
NTP.=20

But I'm not sure if this can only occur when there are multiple daemons =
or
if it can happen=20
in my case too. Browsing through the code in events.c, it looks as it =
could
happen in my case=20
too, although the probability is perhaps small.=20

Has someone a testprogram/argument proving that this is either true or
false?=20

I'm thinking about changing the gettimeofday call in E_get_time to =
something
that is not=20
affected by some external source setting the time, for example,
clock_gettime(CLOCK_MONOTONIC).=20

Has someone done something similar before?=20

Cheers,=20
Drago=20

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Ce message (ainsi que le(s) fichier(s)), transmis par courriel, peut
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destin=E9 =E0
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<p class=3DMsoNormal><font size=3D2 color=3Dnavy face=3DArial><span =
style=3D'font-size:
10.0pt;font-family:Arial;color:navy'>No, not really.=A0 One way you =
could test
would be to see how normal Spread reacts when you jump the clock around =
and
then contrast that with how it operates using your monotonic =
clock.<o:p></o:p></span></font></p>

<p class=3DMsoNormal><font size=3D2 color=3Dnavy face=3DArial><span =
style=3D'font-size:
10.0pt;font-family:Arial;color:navy'><o:p>&nbsp;</o:p></span></font></p>

<div>

<p><font size=3D2 color=3Dnavy face=3D"Times New Roman"><span =
style=3D'font-size:10.0pt;
color:navy'>Cheers!<br>
<br>
---<br>
John Lane Schultz<br>
Spread Concepts LLC<br>
Phn: 443 838 2200 </span></font><o:p></o:p></p>

</div>

<div>

<div class=3DMsoNormal align=3Dcenter style=3D'text-align:center'><font =
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face=3D"Times New Roman"><span style=3D'font-size:12.0pt'>

<hr size=3D2 width=3D"100%" align=3Dcenter tabindex=3D-1>

</span></font></div>

<p class=3DMsoNormal><b><font size=3D2 face=3DTahoma><span =
style=3D'font-size:10.0pt;
font-family:Tahoma;font-weight:bold'>From:</span></font></b><font =
size=3D2
face=3DTahoma><span style=3D'font-size:10.0pt;font-family:Tahoma'>
drago.krznaric at se.transport.bombardier.com
[mailto:drago.krznaric at se.transport.bombardier.com] <br>
<b><span style=3D'font-weight:bold'>Sent:</span></b> Monday, May 11, =
2009 4:18 AM<br>
<b><span style=3D'font-weight:bold'>To:</span></b> John Schultz<br>
<b><span style=3D'font-weight:bold'>Cc:</span></b> <st1:PersonName =
w:st=3D"on">spread-users at lists.spread.org</st1:PersonName><br>
<b><span style=3D'font-weight:bold'>Subject:</span></b> Re: =
[Spread-users] Should
I dare touch the clock?</span></font><o:p></o:p></p>

</div>

<p class=3DMsoNormal><font size=3D3 face=3D"Times New Roman"><span =
style=3D'font-size:
12.0pt'><o:p>&nbsp;</o:p></span></font></p>

Thanky you for prompt reply.
&nbsp;If I would like to try to use the monotonic clock, do you know if =
there
 
is some test suite I could use to =
see that
things work after the change? 
&nbsp; 
Please consider the environment before you print / Merci de penser =E0
l'environnement avant d'imprimer / T=E4nk p=E5 milj=F6n innan du skriver =
ut 
 
<o:p></o:p>

<table class=3DMsoNormalTable border=3D0 cellpadding=3D0 width=3D"100%"
 style=3D'width:100.0%'>
 <tr>
  <td width=3D"35%" valign=3Dtop style=3D'width:35.0%;padding:.75pt =
.75pt .75pt .75pt'>
  <p class=3DMsoNormal><font size=3D3 face=3D"Times New Roman"><span
  style=3D'font-size:12.0pt'><br>
  <br>
  <br>
  </span></font><b><font size=3D1 face=3Dsans-serif><span =
style=3D'font-size:7.5pt;
  font-family:sans-serif;font-weight:bold'>John Schultz
  &lt;jschultz at spreadconcepts.com&gt;</span></font></b> <br>
  <font size=3D1 face=3Dsans-serif><span =
style=3D'font-size:7.5pt;font-family:sans-serif'>2009-05-08
  17:50</span></font> <o:p></o:p></p>
  </td>
  <td width=3D"64%" valign=3Dtop style=3D'width:64.0%;padding:.75pt =
.75pt .75pt .75pt'>
  <table class=3DMsoNormalTable border=3D0 cellpadding=3D0 =
width=3D"100%"
   style=3D'width:100.0%'>
   <tr>
    <td valign=3Dtop style=3D'padding:.75pt .75pt .75pt .75pt'>
    <p class=3DMsoNormal align=3Dright style=3D'text-align:right'><font =
size=3D1
    face=3Dsans-serif><span =
style=3D'font-size:7.5pt;font-family:sans-serif'>To</span></font><o:p></o=
:p></p>
    </td>
    <td valign=3Dtop style=3D'padding:.75pt .75pt .75pt .75pt'>
    <p class=3DMsoNormal><font size=3D1 face=3Dsans-serif><span =
style=3D'font-size:
    7.5pt;font-family:sans-serif'>Drago
    Krznaric/SE/Transport/Bombardier at TRANSPORT</span></font> =
<o:p></o:p></p>
    </td>
   </tr>
   <tr>
    <td valign=3Dtop style=3D'padding:.75pt .75pt .75pt .75pt'>
    <p class=3DMsoNormal align=3Dright style=3D'text-align:right'><font =
size=3D1
    face=3Dsans-serif><span =
style=3D'font-size:7.5pt;font-family:sans-serif'>cc</span></font><o:p></o=
:p></p>
    </td>
    <td valign=3Dtop style=3D'padding:.75pt .75pt .75pt .75pt'>
    <p class=3DMsoNormal><st1:PersonName w:st=3D"on"><font size=3D1 =
face=3Dsans-serif><span
     =
style=3D'font-size:7.5pt;font-family:sans-serif'>spread-users at lists.sprea=
d.org</span></font></st1:PersonName>
    <o:p></o:p></p>
    </td>
   </tr>
   <tr>
    <td valign=3Dtop style=3D'padding:.75pt .75pt .75pt .75pt'>
    <p class=3DMsoNormal align=3Dright style=3D'text-align:right'><font =
size=3D1
    face=3Dsans-serif><span =
style=3D'font-size:7.5pt;font-family:sans-serif'>Subject</span></font><o:=
p></o:p></p>
    </td>
    <td valign=3Dtop style=3D'padding:.75pt .75pt .75pt .75pt'>
    <p class=3DMsoNormal><font size=3D1 face=3Dsans-serif><span =
style=3D'font-size:
    7.5pt;font-family:sans-serif'>Re: [Spread-users] Should I dare touch =
the
    clock?</span></font><o:p></o:p></p>
    </td>
   </tr>
  </table>
  <p class=3DMsoNormal><font size=3D3 face=3D"Times New Roman"><span
  style=3D'font-size:12.0pt'><o:p>&nbsp;</o:p></span></font></p>
  <table class=3DMsoNormalTable border=3D0 cellpadding=3D0>
   <tr>
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    <p class=3DMsoNormal><font size=3D3 face=3D"Times New Roman"><span
    style=3D'font-size:12.0pt'><o:p>&nbsp;</o:p></span></font></p>
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    <p class=3DMsoNormal><font size=3D3 face=3D"Times New Roman"><span
    style=3D'font-size:12.0pt'><o:p>&nbsp;</o:p></span></font></p>
    </td>
   </tr>
  </table>
  <p class=3DMsoNormal><font size=3D3 face=3D"Times New Roman"><span
  style=3D'font-size:12.0pt'><o:p></o:p></span></font></p>
  </td>
 </tr>
</table>

Spread currently uses the wall clock time for =
all of
its time based calculations. &nbsp;If you only move the clock a little, =
then
you probably won't have any issues, although I'm not 100% sure. &nbsp;If =
you
drastically jump the clock forward, then I can see major issues as =
suddenly the
already scheduled timeouts will take forever to fire. &nbsp;If you =
drastically
jump the clock backwards, then a lot of timeouts will fire prematurely, =
which
might cause a spurious partition or something, but the system would =
probably
then return to normal operations immediately thereafter. =
 
 
The
events system definitely should be moved over to using a monotonic clock =
on
whatever platforms such a service is available. &nbsp;We would like to =
do this
sometime in the future, but if you experiment with it and get something =
to work
and want to contribute it back, then that would be great. =
 
 
Cheers!
 
John
 
 
---
 
John
Lane Schultz 
Spread
Concepts LLC 
Phn:
443 838 2200 
Fax:
301 560 8875 
 
Friday,
May 8, 2009, 11:19:23 AM, you wrote: <o:p></o:p>

<table class=3DMsoNormalTable border=3D0 cellpadding=3D0 width=3D"100%"
 style=3D'width:100.0%'>
 <tr>
 <td width=3D"1%" valign=3Dtop bgcolor=3Dblue =
style=3D'width:1.0%;background:blue;
 padding:.75pt .75pt .75pt .75pt'>
 &gt;
 <o:p></o:p>
 </td>
 <td width=3D"98%" valign=3Dtop bgcolor=3Dwhite =
style=3D'width:98.0%;background:white;
 padding:.75pt .75pt .75pt .75pt'>
 
 Hi, 
 
 I
 have a single spread daemon and a bunch of programs communicating via =
spread
 messages 
 through
 this daemon. All programs and the daemon are running on the same =
machine. 
 
 From
 previous mails on this list, I know that people have had problems with
 message 
 delivery
 when they have changed the clock, via settimeofday and even =
NTP. 
 
 But
 I'm not sure if this can only occur when there are multiple daemons or =
if it
 can happen 
 in
 my case too. Browsing through the code in events.c, it looks as it =
could
 happen in my case 
 too,
 although the probability is perhaps small. =
 
 
 Has
 someone a testprogram/argument proving that this is either true or =
false? 
 
 I'm
 thinking about changing the gettimeofday call in E_get_time to =
something that
 is not 
 affected
 by some external source setting the time, for example,
 clock_gettime(CLOCK_MONOTONIC). 
 
 Has
 someone done something similar before? 
 
 Cheers, 
 Drago
 <o:p></o:p>
 </td>
 </tr>
</table>

_________________________________________________________________________=
______________________________________
 
This e-mail communication (and any attachment/s) may contain =
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information systems an AntiSPAM solution is in use and will browse =
through
incoming emails. 
Thank you. 
_________________________________________________________________________=
________________________________________
 
 
Ce message (ainsi que le(s) fichier(s)), transmis par courriel, peut =
contenir
des renseignements confidentiels ou prot=E9g=E9s et est destin=E9 =E0 =
l&#8217;usage
exclusif du destinataire ci-dessus. Toute autre personne est, par les
pr=E9sentes, avis=E9e qu&#8217;il est strictement interdit de le =
diffuser, le
distribuer ou le reproduire. Si vous l&#8217;avez re=E7u par =
inadvertance, veuillez
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antipollupostage (AntiSPAM) est utilis=E9e afin d'assurer la =
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Merci. 
_________________________________________________________________________=
________________________________________
<o:p></o:p>

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