Running strace on the running cups-browsed shows it repeatedly calling poll() with a zero timeout:
poll([{fd=5, events=POLLIN}, {fd=6, events=POLLIN}], 2, 0) = 0 (Timeout) poll([{fd=5, events=POLLIN}, {fd=6, events=POLLIN}], 2, 0) = 0 (Timeout) poll([{fd=5, events=POLLIN}, {fd=6, events=POLLIN}], 2, 0) = 0 (Timeout) poll([{fd=5, events=POLLIN}, {fd=6, events=POLLIN}], 2, 0) = 0 (Timeout) ...
Here, fd 5 is an eventfd and fd 6 is a connection to the D-Bus system bus.
Running strace on the running cups-browsed shows it repeatedly calling poll() with a zero timeout:
poll([{fd=5, events=POLLIN}, {fd=6, events=POLLIN}], 2, 0) = 0 (Timeout)
poll([{fd=5, events=POLLIN}, {fd=6, events=POLLIN}], 2, 0) = 0 (Timeout)
poll([{fd=5, events=POLLIN}, {fd=6, events=POLLIN}], 2, 0) = 0 (Timeout)
poll([{fd=5, events=POLLIN}, {fd=6, events=POLLIN}], 2, 0) = 0 (Timeout)
...
Here, fd 5 is an eventfd and fd 6 is a connection to the D-Bus system bus.