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Use this module for online tracking of perf metrics. When using this module, the metrics are written out to stdout every second. There is no mertric file generated for offline analysis. The rate at which metrics are dumped to stdout is controlled by the environment variable CORE_PROFILER=PRINT_INTERVAL=N where N is the integer number of seconds to wait between outputs.
Profiler.don't_check_env is a no-op, provided for compatibility with Offline's interface. Time_stamp_counter calibration is liable to happen occasionally when calling at. safe_to_delay checks if it will be necessary soon, and does it in advance. If possible, call safe_to_delay (fairly regularly) from a time-insensitive point in code (or at least, outside any deltas / groups) to reduce the number of spurious jumps in time deltas.
This is how much the online probes cost. I don't know how much I trust these metrics, but here they are:
A Timer contains only a time stamp and no extra information; however, it is useful because (in Offline) the current time is recorded when measurements are made.