问题
I want to provide a global io_service that is driven by one global thread. Simple enough, I just have the thread body call io_service::run(). However, that doesn't work as run (run_one, poll, poll_one) return if there is no work to do. But, if the thread repeatedly calls run(), it will busy loop when there is nothing to do.
I'm looking for a way to get the thread to block while there isn't any work to be done in the io_service. I could add a global event to the mix for the thread to block on. However, that would require users of the io_service to notify the event every time they used the service. Not the ideal solution.
Note: there are no actual globals and I never use events for concurrency I just simplified the problem down to my exact need. The real goal is a asio::deadline_timer subclass that doesn't require an io_service as a construction parameter.
回答1:
You need to create an io_service::work object.
See this section of the documentation:
Stopping the io_service from running out of work
来源：https://stackoverflow.com/questions/1942550/dedicated-thread-for-io-servicerun