How Can I Optimize My Bash Script That Collects Data Every 10 Seconds?
Asked by
CuriousCoder27
I've created a bash script that collects data from a solar inverter every 10 seconds for a duration of 5 minutes. It performs some calculations and then sends the data to a platform. While it works, I'm noticing that the CPU usage is quite high, peaking at about 80%. I'm looking for an effective way to manage the timing for the next data collection without running a time-consuming loop. Specifically, I want to improve line 7 of my script. Here's a simplified version of it:
```bash
#!/bin/bash
set -o pipefail
IFS=$''
samples="0"
nr="0"
while [ $SECONDS -lt 292 ]; do #5min-8s
if [[ (( $(( (samples - 1) * 10 + 10 )) == $SECONDS )) || (( 0 == $SECONDS )) ]]; then
((samples++))
timestart=$SECONDS
output="$(./inverter_poller --run-once)" # get data from inverter
timeend=$SECONDS
echo ${output} > /var/log/inverter.last
rs232time=$((timeend - timestart)) # usually it is 6-7 seconds
if (( rs232time > /var/log/inverter.last
fi
looptime=$((SECONDS - timestart))
echo "time": $looptime >> /var/log/inverter.last
fi
done
***boring data processing and sending to emoncms was here***
```
Any suggestions for optimizing my script?
Answers
Your issue seems to stem from the continuous looping of your script, resulting in high CPU usage. Instead, you might want to introduce a sleep command after you fetch the data. For instance:
```bash
while [ $SECONDS -lt 292 ]; do
((samples++))
timestart=$SECONDS
output="$(./inverter_poller --run-once)" # get data from inverter
timeend=$SECONDS
echo ${output} > /var/log/inverter.last
rs232time=$((timeend - timestart)) # usually 6-7 seconds
if (( rs232time > /var/log/inverter.last
fi
looptime=$((SECONDS - timestart))
echo "time": $looptime >> /var/log/inverter.last
sleep 10
done
```
This will effectively create a 10-second pause between each data collection and should help reduce CPU spikes significantly. You can even adjust the sleep duration depending on your specific timing needs.
Reply to this answer
Add your answer
Answers are reviewed before publication.
ScriptGuru45: I ran into issues with sleep because my loop was often taking longer than expected on some iterations. One workaround I found is to check the time taken and only sleep for the remaining duration: ```bash if (( $looptime < 10 )); then sleep $((10 - $looptime)); fi ``` Just ensure that you handle cases where the operation might take longer than 10 seconds.
SmartScripter88: That's a good strategy! Also, if your rs232time consistently exceeds 10 seconds, you might want to log that and alert yourself instead of losing the readings.