When gperftools CPU profiling is enabled for a specifically bracketed operation, using ProfilerStart() and ProfilerStop(), and the operation is a very long-running one, it can be useful for the client to flush the statistics during the operation: output can be examined while the operation is running to see what is going on, some stats are available in the event of an abort, etc. It's precisely the long-running operations that benefit most from not losing the stats at the end if something goes wrong.

The attached patch allows calling ProfileFlush in a way similar to start/stop.