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<p class=MsoNormal><span lang=IS>Hello all. <o:p></o:p></span></p>

<p class=MsoNormal><span lang=IS>I was recently asked to re-enable our profiler
after we moved from stackless 2.3 to 2.5.  After the switch, it had stopped
working.<o:p></o:p></span></p>

<p class=MsoNormal><span lang=IS><o:p>&nbsp;</o:p></span></p>

<p class=MsoNormal><span lang=IS>Our profiler is a sublclass of
profile.Profile, and properly deals with context switches by saving and
restoring the profiling context when we move between tasklets.<o:p></o:p></span></p>

<p class=MsoNormal><span lang=IS><o:p>&nbsp;</o:p></span></p>

<p class=MsoNormal><span lang=IS>Now, I have two problems.<o:p></o:p></span></p>

<p class=MsoNormal><span lang=IS><o:p>&nbsp;</o:p></span></p>

<p class=MsoListParagraph style='text-indent:-18.0pt;mso-list:l0 level1 lfo1'><![if !supportLists]><span
lang=IS><span style='mso-list:Ignore'>1)<span style='font:7.0pt "Times New Roman"'>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;
</span></span></span><![endif]><span lang=IS>The stuff crashes in eve.  I have
not been able to repro the crash in the standard 2.5 thing, but I have enclosed
a demo that shows mysterious behaviour.  We never reach the &#8222;print ´b´&#8220;
code at all, and get some internal error there too (myprofile.py is just
profile.py with a print statement in there)<o:p></o:p></span></p>

<p class=MsoListParagraph style='text-indent:-18.0pt;mso-list:l0 level1 lfo1'><![if !supportLists]><span
lang=IS><span style='mso-list:Ignore'>2)<span style='font:7.0pt "Times New Roman"'>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;
</span></span></span><![endif]><span lang=IS>It would appear that stackless now
only profiles on the main tasklet, that is, turns off profiling on other
tasklets.  This is a change of behaviour from the old days. <o:p></o:p></span></p>

<p class=MsoNormal><span lang=IS><o:p>&nbsp;</o:p></span></p>

<p class=MsoNormal><span lang=IS>After debugging a lot, it appears to me that
something is heavily wrong with task switching in this scenario.  At least in
EVE.  I didn&#8216;t turn on the debugger for the standalone python yet.  It
also appears somehow related to point 2) above, particularly the &#8222;restore_tracing()&#8220;
callback in scheduling.c.   <o:p></o:p></span></p>

<p class=MsoNormal><span lang=IS><o:p>&nbsp;</o:p></span></p>

<p class=MsoNormal><span lang=IS>Does anyone have a clue what is going on?<o:p></o:p></span></p>

<p class=MsoNormal><span lang=IS><o:p>&nbsp;</o:p></span></p>

<p class=MsoNormal><span lang=IS>And how are the profiling (and tracing)
semantics in stackless now wrt. tasklets?  Does it save and restore the tracing
state in each tasklet?<o:p></o:p></span></p>

<p class=MsoNormal><span lang=IS><o:p>&nbsp;</o:p></span></p>

<p class=MsoNormal><span lang=IS>If we manage to figure out what is going on
here, I would like to be able to have the old profiling behaviour again.  That
is, that profiling is a per-thread global state which can be turned on and off
to capture profiling information about a running stackless program.  Any
objections?<o:p></o:p></span></p>

<p class=MsoNormal><span lang=IS><o:p>&nbsp;</o:p></span></p>

<p class=MsoNormal><span lang=IS>Cheers,<o:p></o:p></span></p>

<p class=MsoNormal><span lang=IS>Kristján<o:p></o:p></span></p>

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