Maybe we have to look at the overall architecture. I don't know whether you have influence on the other side of the application. If yes, it probably would be better to let the other side to inform you when it is the time to query. This can be done thru UDP, or something similar. Then, on this side, you only needs two threads, one to monitor socket (thru fcntl, let the system tell you when you have some packets to read, not sleep/awake...), the other one to really do the collection.

It is never a good idea to use thread together with sleep. Performance goes down quite a lot.

Unfortunately, alarm is not a choice, system does not stack alarms, and only the last one take effects. Internally, the system has an single itimer, and it would be reset everytime you call alarm. Also the signal probably will be delivered to the process, not the thread.