This breaks test_local_instrument because it assumes that you can:

• run experiment in background process
• end background process
• sync data over to main process

@jenshnielsen

...
run experiment in background process

Does that mean your small change there will make background loops with the current multiprocessing stuff totally impossible?

This change makes it impossible to read the data into the main process using sync. This is probably not the right fix but the current code is fairly convoluted. It's probably better to prevent plot.update from calling sync on default

Test added