Did you check if persistent=True makes any difference?

> On 6 Aug 2020, at 16:21, Mick Sulley <m...@sulley.info> wrote:
> 
> Well this gets more curious.  I am now measuring the time for each read, 
> reading type, power and latesttemp.  Time for all is generally < 0.1 seconds, 
> but then when I hit the slow loop the read for type is around 0.7 seconds, 
> the others still < 0.1 seconds.  I don't really need type so I removed it and 
> re-tested, on slow loops the power read is around 0.7 seconds, latesttemp 
> still < 0.1 seconds.  So I removed power as well, just reading latesttemp, on 
> slow loops that is now around 0.7 seconds.  So it seems that at some point a 
> sensor takes many times longer for its next read, irrespective of which field 
> is read.
> 
> I have now tested with 19, 11 and 2 sensors and the slow loop occurs every 
> 120 seconds.  I am intrigued to know what causes this, any ideas?
> 
> Thanks
> 
> Mick
> 
> On 06/08/2020 10:23, Mick Sulley wrote:
>> OK I will log read times and see what that shows.
>> 
>> You say 'I also log if the error of the 1wire bus changes.' how do you do 
>> that?
>> 
>> No I don't really need to read that fast, this is just a test setup to get a 
>> better understanding so I can hopefully fine tune my main system.
>> 
>> There should not be anything else running.  I just tried running top at the 
>> same time, I monitored it at the point of the slow scan and didn't see 
>> anything else significant.
>> 
>> Mick
>> 
>> On 06/08/2020 09:06, Martin Patzak wrote:
>>> It looks like your timing has improved after all!
>>> 
>>> in your original Python-code you could time every read for each sensor.
>>> I have also powered sensors and a read is usually faster than 0.1 seconds.
>>> I log in a file if the read took longer than 0.3 seconds, which is almost 
>>> never the case.
>>> I also log in the file if the whole reading loop took longer than 3 
>>> seconds, which again is almost never the case.
>>> 
>>> I also log if the error of the 1wire bus changes.
>>> 
>>> I read 25 sensors every full and every half minute, so maybe you could 
>>> implement a delay as well and see if things get more consistent.
>>> Do you need to read so fast in a loop for you application?
>>> 
>>> What else is running on your machine? You could run top in parallel to your 
>>> python loop.
>>> 
>>> 
>> 
>> 
>> 
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