1.問題描述：

啟動spark-shell local的模式

bin/spark-shell --master local[2]

報錯：

[[email protected] spark-2.1.0-bin-hadoop2.6]$ bin/spark-shell --master local[2]
Setting default log level to "WARN".
To adjust logging level use sc.setLogLevel(newLevel). For SparkR, use setLogLevel(newLevel).
18/11/03 10:54:04 WARN NativeCodeLoader: Unable to load native-hadoop library for your platform... using builtin-java classes where applicable
18/11/03 10:54:35 ERROR PoolWatchThread: Error in trying to obtain a connection. Retrying in 7000ms
java.sql.SQLException: A read-only user or a user in a read-only database is not permitted to disable read-only mode on a connection.
        at org.apache.derby.impl.jdbc.SQLExceptionFactory.getSQLException(Unknown Source)
        at org.apache.derby.impl.jdbc.Util.generateCsSQLException(Unknown Source)
        at org.apache.derby.impl.jdbc.TransactionResourceImpl.wrapInSQLException(Unknown Source)
        at org.apache.derby.impl.jdbc.TransactionResourceImpl.handleException(Unknown Source)
        at org.apache.derby.impl.jdbc.EmbedConnection.handleException(Unknown Source)
        at org.apache.derby.impl.jdbc.EmbedConnection.setReadOnly(Unknown Source)
        at com.jolbox.bonecp.ConnectionHandle.setReadOnly(ConnectionHandle.java:1324)
        at com.jolbox.bonecp.ConnectionHandle.<init>(ConnectionHandle.java:262)
        at com.jolbox.bonecp.PoolWatchThread.fillConnections(PoolWatchThread.java:115)
        at com.jolbox.bonecp.PoolWatchThread.run(PoolWatchThread.java:82)
        at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1149)
        at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:624)
        at java.lang.Thread.run(Thread.java:748)
Caused by: ERROR 25505: A read-only user or a user in a read-only database is not permitted to disable read-only mode on a connection.
        at org.apache.derby.iapi.error.StandardException.newException(Unknown Source)
        at org.apache.derby.iapi.error.StandardException.newException(Unknown Source)
        at org.apache.derby.impl.sql.conn.GenericAuthorizer.setReadOnlyConnection(Unknown Source)
        at org.apache.derby.impl.sql.conn.GenericLanguageConnectionContext.setReadOnly(Unknown Source)
        ... 8 more
18/11/03 10:54:42 ERROR PoolWatchThread: Error in trying to obtain a connection. Retrying in 7000ms
java.sql.SQLException: A read-only user or a user in a read-only database is not permitted to disable read-only mode on a connection.
        at org.apache.derby.impl.jdbc.SQLExceptionFactory.getSQLException(Unknown Source)
        at org.apache.derby.impl.jdbc.Util.generateCsSQLException(Unknown Source)
        at org.apache.derby.impl.jdbc.TransactionResourceImpl.wrapInSQLException(Unknown Source)
        at org.apache.derby.impl.jdbc.TransactionResourceImpl.handleException(Unknown Source)
        at org.apache.derby.impl.jdbc.EmbedConnection.handleException(Unknown Source)
        at org.apache.derby.impl.jdbc.EmbedConnection.setReadOnly(Unknown Source)
        at com.jolbox.bonecp.ConnectionHandle.setReadOnly(ConnectionHandle.java:1324)
        at com.jolbox.bonecp.ConnectionHandle.<init>(ConnectionHandle.java:262)
        at com.jolbox.bonecp.PoolWatchThread.fillConnections(PoolWatchThread.java:115)
        at com.jolbox.bonecp.PoolWatchThread.run(PoolWatchThread.java:82)
        at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1149)
        at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:624)
        at java.lang.Thread.run(Thread.java:748)
Caused by: ERROR 25505: A read-only user or a user in a read-only database is not permitted to disable read-only mode on a connection.
        at org.apache.derby.iapi.error.StandardException.newException(Unknown Source)
        at org.apache.derby.iapi.error.StandardException.newException(Unknown Source)
        at org.apache.derby.impl.sql.conn.GenericAuthorizer.setReadOnlyConnection(Unknown Source)
        at org.apache.derby.impl.sql.conn.GenericLanguageConnectionContext.setReadOnly(Unknown Source)
        ... 8 more
 

2.問題原因：

可能是由於之前的操作失誤，錯誤關閉了spark，生成了一個檔案db.lck，導致無法啟動。

3.解決：

刪除/opt/modules/spark-2.1.0-bin-hadoop2.6/metastore_db下的db.loc

rm -rf db.lck 

（一步一個坑！）