This is automatic generated document for things in Swow\Watchdog class
When it is callable, it will be called when blocking occurred, the developer can choose to suspend the coroutine or kill the coroutine; when it is numeric, Coroutine will be delayed to run with sleep() in millisecond to alleviate CPU starvation; when it is null, Coroutine will be delayed to run at the next round of the event loop starts to alleviate CPU starvation.
int $quantum Nanoseconds, if the blocking time exceeds the quantum, alerter will be triggered. Param
int $threshold Nanoseconds, if the blocking time exceeds the threshold (means the alerter does not alleviate the CPU starvation), it is considered that the system call blocking occurred.