Hello,
I've been trying to figure this problem out for some time now and I'm
totally stuck. The Exception in question is the following:
Caused by: java.lang.NullPointerException
at com.mysql.jdbc.ResultSetImpl.next(ResultSetImpl.java:7009)
at
com.server.persistence.state.connectors.jdbc.JDBCCleanupStateConnector.getUUIDsByTable(JDBCCleanupStateConnector.java:140)
... 8 more
It occurs very infrequently (and unfortunately I have not been able to
reproduce it yet). I have also checked all occurences of getConnection().
Every one of them is wrapped (like below) by try {} finally {if (con !=
null) con.close();}. Connections are not stored locally and used by other
threads later as far as I can tell either.
The last time this problem occured, the thread in question was actually
stuck for 10 minutes (as far as I reconstruct) before the NPE was thrown.
During this time, the thread was seemingly stuck on
SocketInputStream.socketRead0 (see below for stack trace), even though I
set the sockettimeout when creating the db pool.
We're using MySQL Connector/J 5.1.24 (but there are no changes regarding
anything like this problem in 5.1.25 or 5.1.26 - and this problem has
persisted for some versions already) and Tomcat's JDBC Pool 7.0.42.
Best regards
Henning Rohlfs
@Override
public ListString getUUIDsByTable( final String table) throws
TableNotFoundException {
Connection connection = null;
try {
connection = stateDbIo.getConnection();
final PreparedStatement ps = connection.prepareStatement(
SELECT uuid FROM ` + table+ ` GROUP BY uuid );
final ResultSet rs = ps.executeQuery();
final ListString result = new ArrayListString();
while ( rs.next() ) { //this is where the exception is thrown
result.add( rs.getString( UUID_COLUMN ) );
}
return result;
} catch ( final Exception e ) {
throw new TableNotFoundException( table, e );
} finally {
if ( connection != null ) {
try {
connection.close();
} catch ( final SQLException e ) {
// ignore
}
}
}
}
I'm using the tomcat jdbc database pool (7.0.42) to get the connections.
stateDbIo.getConnection():
public Connection getConnection() throws SQLException {
if ( dataSource != null ) {
final Connection connection = dataSource.getConnection();
connection.setReadOnly( readOnly );
connection.setAutoCommit( true );
return connection;
}
return null;
}
Connection pool settings:
protected String initialSize = 0;
protected String maxActive = 8;
protected String maxIdle = 8;
protected String minIdle = 0;
protected String timeBetweenEvictionRunsMillis = 3;
protected String minEvictableIdleTimeMillis = 6;
protected String validationQuery = SELECT 1;
protected String validationInterval = 3;
protected String testOnBorrow = true;
protected String removeAbandoned = true;
protected String removeAbandonedTimeout = 60;
protected String logAbandoned = true;
protected String jdbcInterceptors =
org.apache.tomcat.jdbc.pool.interceptor.ConnectionState; +
org.apache.tomcat.jdbc.pool.interceptor.StatementFinalizer; +
org.apache.tomcat.jdbc.pool.interceptor.ResetAbandonedTimer;
protected String connectionProperties =
[connectTimeout=9;socketTimeout=9;];
props = new Properties();
props.put( url, url );
props.put( driverClassName, driverClass );
props.put( username, username );
props.put( password, password );
props.put( initialSize, initialSize );
props.put( maxActive, maxActive );
props.put( maxIdle, maxIdle );
props.put( minIdle, minIdle );
props.put( timeBetweenEvictionRunsMillis,
timeBetweenEvictionRunsMillis );
props.put( minEvictableIdleTimeMillis, minEvictableIdleTimeMillis
);
props.put( validationQuery, validationQuery );
props.put( validationInterval, validationInterval );
props.put( testOnBorrow, testOnBorrow );
props.put( removeAbandoned, removeAbandoned );
props.put( removeAbandonedTimeout, removeAbandonedTimeout ); //
seconds
props.put( logAbandoned, logAbandoned );
props.put( connectionProperties, connectionProperties );
props.put( jdbcInterceptors, jdbcInterceptors );
return new DataSourceFactory().createDataSource( props );
Stack trace of stuck thread before it threw the exception:
java.lang.Thread.State: RUNNABLE
at java.net.SocketInputStream.
socketRead0(Native Method)
at java.net.SocketInputStream.read(SocketInputStream.java:150)
at java.net.SocketInputStream.read(SocketInputStream.java:121)
at
