Returns the thread keep-alive time, which is the amount of time
that threads may remain idle before being terminated.
Threads that wait this amount of time without processing a
task will be terminated if there are more than the core
number of threads currently in the pool, or if this pool
{@linkplain #allowsCoreThreadTimeOut() allows core thread timeout}.
@param unit the desired time unit of the result
@return the time limit
@see #setKeepAliveTime(long, TimeUnit)
Returns the thread keep-alive time, which is the amount of time that threads may remain idle before being terminated. Threads that wait this amount of time without processing a task will be terminated if there are more than the core number of threads currently in the pool, or if this pool {@linkplain #allowsCoreThreadTimeOut() allows core thread timeout}.
@param unit the desired time unit of the result @return the time limit @see #setKeepAliveTime(long, TimeUnit)