Refactoring multi thread program on raspberry pi with sensors

Question

I am doing a IoT experiment with raspberry pis and sensors aiming to monitor temperature change. Each raspberry pi is connected to multiple sensors. My goal is to have one reading per sensor per second, store the data in a buffer(real buffer or a csv file) and publish the data to a broker. The program now is doing all things in queue. It turns out some delay. I have tested and it turns out the delay comes from reading process. Is there any way to reduce reading delay? Will multi threading solve this problem? If so, what I think is to create 3 thread. Sensor thread read the data and store in a buffer. Communicator thread connect to the broker, read the data in buffer and send it to the broker. Main thread will manage sensor thread and communicator thread. If I refactor the program in this way, do I write one sensor thread for each sensor or one sensor thread for all sensors?

Any suggestions will be greatly appreciated.

Answer 1

Before re-engineering your application, you should narrow down where the bottleneck is. To diagnose this, I would try logging the start and end of each read from your sensors to a string buffer you keep in memory. Do this for 30 seconds or so. Then, stop reading from the sensors and write the buffer to a log file. If the log file shows delays between the start and end of each of the sensor reads, then that's where the bottleneck is. If it doesn't, then the bottleneck is probably in continually writing your CSV file to disk.