Caused by: javax.net.ssl.SSLException: Unsupported or unrecognized SSL message
        at sun.security.ssl.SSLSocketInputRecord.handleUnknownRecord(SSLSocketInputRecord.java:448)
        at sun.security.ssl.SSLSocketInputRecord.decode(SSLSocketInputRecord.java:174)
        at sun.security.ssl.SSLTransport.decode(SSLTransport.java:110)
        at sun.security.ssl.SSLSocketImpl.decode(SSLSocketImpl.java:1290)
        at sun.security.ssl.SSLSocketImpl.readHandshakeRecord(SSLSocketImpl.java:1199)
        at sun.security.ssl.SSLSocketImpl.startHandshake(SSLSocketImpl.java:401)
        at sun.security.ssl.SSLSocketImpl.startHandshake(SSLSocketImpl.java:373)

package me.tianshuang;

import java.util.concurrent.Executors;
import java.util.concurrent.TimeUnit;

public class ScheduledExecutorServiceTest {

    public static void main(String[] args) {
        Executors.newSingleThreadScheduledExecutor()
                .scheduleAtFixedRate(() -> System.out.println("I'm running..."), 1, 1, TimeUnit.SECONDS);
    }

}

/**
 * Executes the given task sometime in the future.  The task
 * may execute in a new thread or in an existing pooled thread.
 *
 * If the task cannot be submitted for execution, either because this
 * executor has been shutdown or because its capacity has been reached,
 * the task is handled by the current {@code RejectedExecutionHandler}.
 *
 * @param command the task to execute
 * @throws RejectedExecutionException at discretion of
 *         {@code RejectedExecutionHandler}, if the task
 *         cannot be accepted for execution
 * @throws NullPointerException if {@code command} is null
 */
public void execute(Runnable command) {
    if (command == null)
        throw new NullPointerException();
    /*
     * Proceed in 3 steps:
     *
     * 1. If fewer than corePoolSize threads are running, try to
     * start a new thread with the given command as its first
     * task.  The call to addWorker atomically checks runState and
     * workerCount, and so prevents false alarms that would add
     * threads when it shouldn't, by returning false.
     *
     * 2. If a task can be successfully queued, then we still need
     * to double-check whether we should have added a thread
     * (because existing ones died since last checking) or that
     * the pool shut down since entry into this method. So we
     * recheck state and if necessary roll back the enqueuing if
     * stopped, or start a new thread if there are none.
     *
     * 3. If we cannot queue task, then we try to add a new
     * thread.  If it fails, we know we are shut down or saturated
     * and so reject the task.
     */
    int c = ctl.get();
    if (workerCountOf(c) < corePoolSize) {
        if (addWorker(command, true))
            return;
        c = ctl.get();
    }
    if (isRunning(c) && workQueue.offer(command)) {
        int recheck = ctl.get();
        if (! isRunning(recheck) && remove(command))
            reject(command);
        else if (workerCountOf(recheck) == 0)
            addWorker(null, false);
    }
    else if (!addWorker(command, false))
        reject(command);
}