启动spark的操作是在其根目录下输入，在终端中输入：
./bin/spark-shell
退出的正确操作是：
:quit
然而我们的错误操作是：
Ctrl+C或Z
这样就会在重启的时候报错。
wugaosheng:spark-2.2.0-bin-hadoop2.7 eric$ ./bin/spark-shell
Using Spark's default log4j profile: org/apache/spark/log4j-defaults.properties
Setting default log level to "WARN".
To adjust logging level use sc.setLogLevel(newLevel). For SparkR, use setLogLevel(newLevel).
17/10/06 17:15:20 WARN NativeCodeLoader: Unable to load native-hadoop library for your platform... using builtin-java classes where applicable
17/10/06 17:15:26 WARN Utils: Service 'SparkUI' could not bind on port 4040. Attempting port 4041.
17/10/06 17:15:33 ERROR Schema: Failed initialising database.
Unable to open a test connection to the given database. JDBC url = jdbc:derby:;databaseName=metastore_db;create=true, username = APP. Terminating connection pool (set lazyInit to true if you expect to start your database after your app). Original Exception: ------
java.sql.SQLException: Failed to start database 'metastore_db' with class loader org.apache.spark.sql.hive.client.IsolatedClientLoader$$anon$1@30517a57, see the next exception for details.
at org.apache.derby.impl.jdbc.SQLExceptionFactory.getSQLException(Unknown Source)
at org.apache.derby.impl.jdbc.SQLExceptionFactory.getSQLException(Unknown Source)
at org.apache.derby.impl.jdbc.Util.seeNextException(Unknown Source)
at org.apache.derby.impl.jdbc.EmbedConnection.bootDatabase(Unknown Source)
at org.apache.derby.impl.jdbc.EmbedConnection.<init>(Unknown Source)
at org.apache.derby.jdbc.InternalDriver$1.run(Unknown Source)
at org.apache.derby.jdbc.InternalDriver$1.run(Unknown Source)
at java.security.AccessController.doPrivileged(Native Method)
at org.apache.derby.jdbc.InternalDriver.getNewEmbedConnection(Unknown Source)
at org.apache.derby.jdbc.InternalDriver.connect(Unknown Source)
at org.apache.derby.jdbc.InternalDriver.connect(Unknown Source)
at org.apache.derby.jdbc.AutoloadedDriver.connect(Unknown Source)
at java.sql.DriverManager.getConnection(DriverManager.java:664)
at java.sql.DriverManager.getConnection(DriverManager.java:208)
at com.jolbox.bonecp.BoneCP.obtainRawInternalConnection(BoneCP.java:361)
at com.jolbox.bonecp.BoneCP.<init>(BoneCP.java:416)
at com.jolbox.bonecp.BoneCPDataSource.getConnection(BoneCPDataSource.java:120)
at org.datanucleus.store.rdbms.ConnectionFactoryImpl$ManagedConnectionImpl.getConnection(ConnectionFactoryImpl.java:501)
at org.datanucleus.store.rdbms.RDBMSStoreManager.<init>(RDBMSStoreManager.java:298)
at sun.reflect.NativeConstructorAccessorImpl.newInstance0(Native Method)
at sun.reflect.NativeConstructorAccessorImpl.newInstance(NativeConstructorAccessorImpl.java:62)
at sun.reflect.DelegatingConstructorAccessorImpl.newInstance(DelegatingConstructorAccessorImpl.java:45)
at java.lang.reflect.Constructor.newInstance(Constructor.java:423)
at org.datanucleus.plugin.NonManagedPluginRegistry.createExecutableExtension(NonManagedPluginRegistry.java:631)
at org.datanucleus.plugin.PluginManager.createExecutableExtension(PluginManager.java:301)
at org.datanucleus.NucleusContext.createStoreManagerForProperties(NucleusContext.java:1187)
at org.datanucleus.NucleusContext.initialise(NucleusContext.java:356)
at org.datanucleus.api.jdo.JDOPersistenceManagerFactory.freezeConfiguration(JDOPersistenceManagerFactory.java:775)
at org.datanucleus.api.jdo.JDOPersistenceManagerFactory.createPersistenceManagerFactory(JDOPersistenceManagerFactory.java:333)
at org.datanucleus.api.jdo.JDOPersistenceManagerFactory.getPersistenceManagerFactory(JDOPersistenceManagerFactory.java:202)
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
at java.lang.reflect.Method.invoke(Method.java:498)
at javax.jdo.JDOHelper$16.run(JDOHelper.java:1965)
at java.security.AccessController.doPrivileged(Native Method)
at javax.jdo.JDOHelper.invoke(JDOHelper.java:1960)
at javax.jdo.JDOHelper.invokeGetPersistenceManagerFactoryOnImplementation(JDOHelper.java:1166)
at javax.jdo.JDOHelper.getPersistenceManagerFactory(JDOHelper.java:808)
at javax.jdo.JDOHelper.getPersistenceManagerFactory(JDOHelper.java:701)
at org.apache.hadoop.hive.metastore.ObjectStore.getPMF(ObjectStore.java:365)
at org.apache.hadoop.hive.metastore.ObjectStore.getPersistenceManager(ObjectStore.java:394)
at org.apache.hadoop.hive.metastore.ObjectStore.initialize(ObjectStore.java:291)
at org.apache.hadoop.hive.metastore.ObjectStore.setConf(ObjectStore.java:258)
at org.apache.hadoop.util.ReflectionUtils.setConf(ReflectionUtils.java:76)
at org.apache.hadoop.util.ReflectionUtils.newInstance(ReflectionUtils.java:136)
at org.apache.hadoop.hive.metastore.RawStoreProxy.<init>(RawStoreProxy.java:57)
at org.apache.hadoop.hive.metastore.RawStoreProxy.getProxy(RawStoreProxy.java:66)
at org.apache.hadoop.hive.metastore.HiveMetaStore$HMSHandler.newRawStore(HiveMetaStore.java:593)
at org.apache.hadoop.hive.metastore.HiveMetaStore$HMSHandler.getMS(HiveMetaStore.java:571)
at org.apache.hadoop.hive.metastore.HiveMetaStore$HMSHandler.createDefaultDB(HiveMetaStore.java:620)
.......
输出了很长的错误信息，并且输入正常的代码会报错。
这时候就需要删除spark目录下的metastore_db文件夹，如我的命令：
mv metastore_db/ metastore_db1/
这时候再重启就不会输出那么多错误信息了
如果想杀掉4040端口进程，我的Mac为例：
sudo lsof -i :4040
会输出如下信息：
COMMAND PID USER FD TYPE DEVICE SIZE/OFF NODE NAME
java 38639 eric 262u IPv6 0x731427fd0077f5d 0t0 TCP *:yo-main (LISTEN)
然后运行：
sudo kill -9 38639
这样，占用的端口就可以重新使用了
参考文献
[1]. 1.Spark启动时hive出现another instance of derby may have already booted the database的错误.
[2].【Linux—Spark1.1.0】spark-shell强制关闭再重启导致的端口占用问题.http://blog.sina.com.cn/s/blog_49cd89710102v1hl.html
[3]. MAC OS查看端口占用情况及杀死进程
