public static void shutdown() {
        ScheduledExecutorService exec = PURGE_THREAD.getAndSet(null);
        if (exec != null) {
            exec.shutdownNow();
        }
        POOLS.clear();
    }
public static void shutdown() {
        ScheduledExecutorService exec = PURGE_THREAD.getAndSet(null);
        if (exec != null) {
            exec.shutdownNow();
        }
        POOLS.clear();
    }
public static void shutdown ( ) { ScheduledExecutorService exec = PURGE_THREAD . getAndSet ( null ) ; if ( exec != null ) { exec . shutdownNow ( ) ; } POOLS . clear ( ) ; }
Stops the purge thread.
Stops the purge thread .