Anomaly in time.clock()

Ross Ridge rridge at caffeine.csclub.uwaterloo.ca
Wed Mar 19 18:15:08 CET 2008


Godzilla  <godzillaismad at gmail.com> wrote:
>But the time.clock() sometimes return a value of between -3.5 to -4.5
>seconds backward.

There are race conditions in your code.  In between the time you execute
"curTime = time.clock()" and calculate "curTime - self.timeStamp" in one
thread, the other thread can execute "self.timeStamp = time.clock()".
It's the only way your example program can print a negative "Actual
Elapsed Time" value.  The race condition seems unlikely, and it's hard
to explain how this could result in it printing a value in the range
of -3.5 to -4.5.  However, a race condition occuring between the two
evaluations of "curTime - self.timeStamp" is the only way your example
program could print a negative value.

					Ross Ridge

-- 
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[oo][oo]  rridge at csclub.uwaterloo.ca
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