I run this query every minute and I have this exception after couple of hours...
Class.forName("org.mariadb.jdbc.Driver");
conn = DriverManager.getConnection(DB_URL, USER, PASS);
stmt = conn.createStatement();
String sql = "SHOW STATUS LIKE 'wsrep_%'";
rs = stmt.executeQuery(sql);

Is there something i can do to get root cause of that exception?
Thank you,
vic


On Wed, Dec 21, 2016 at 2:55 PM, Vladislav Vaintroub <vvaintroub@gmail.com> wrote:

"SHOW STATUS" fails because server closes the client socket. 

"Could not read resultset: unexpected end of stream, read 0 bytes from 4" is a slightly weird message,  but client reads 0 bytes instead of packet header(4 bytes). Reading 0 bytes which means socket was closed orderly (as opposed to e.g aborting connection with SO_LINGER or server maybe server crash). 

Why does server closes the socket, and what happened otherwise, I do not know.  The error log hints at memory shortage.


On 21.12.2016 20:45, l vic wrote:
Have the following error trace from running 
SHOW STATUS LIKE 'wsrep_%'
Any idea what could cause it?

2016-12-21  3:39:24 139668819036928 [Note] InnoDB: Online DDL : End of applying row log
2016-12-21  3:39:24 139668819036928 [Note] InnoDB: Online DDL : Completed
2016-12-21  3:43:29 139668818733824 [Note] InnoDB: Online DDL : Start
2016-12-21  3:43:29 139668818733824 [Note] InnoDB: Online DDL : Start reading clustered index of the table and create temporary files
2016-12-21 03:43:29 7f072e53ab00 InnoDB: Error: Write to file (merge) failed at offset 0.
InnoDB: 1048576 bytes should have been written, only 901120 were written.
InnoDB: Operating system error number 12.
InnoDB: Check that your OS and file system support files of this size.
InnoDB: Check also that the disk is not full or a disk quota exceeded.
InnoDB: Error number 12 means 'Cannot allocate memory'.
InnoDB: Some operating system error numbers are described at
InnoDB: http://dev.mysql.com/doc/refman/5.6/en/operating-system-error-codes.html
2016-12-21  3:43:29 139668818733824 [Note] InnoDB: Online DDL : End of reading clustered index of the table and create temporary files
java.sql.SQLNonTransientConnectionException: (conn:17945) Could not read resultset: unexpected end of stream, read 0 bytes from 4
Query is : SHOW STATUS LIKE 'wsrep_%'
	at org.mariadb.jdbc.internal.util.ExceptionMapper.get(ExceptionMapper.java:132)
	at org.mariadb.jdbc.internal.util.ExceptionMapper.getException(ExceptionMapper.java:101)
	at org.mariadb.jdbc.internal.util.ExceptionMapper.throwAndLogException(ExceptionMapper.java:77)
	at org.mariadb.jdbc.MariaDbStatement.executeQueryEpilog(MariaDbStatement.java:224)
	at org.mariadb.jdbc.MariaDbStatement.executeInternal(MariaDbStatement.java:258)
	at org.mariadb.jdbc.MariaDbStatement.executeQuery(MariaDbStatement.java:371)
	at com.verizon.mesos.Dbcheck.getStatus(Dbcheck.java:153)
	at com.verizon.mesos.Dbcheck.run(Dbcheck.java:103)
	at com.verizon.mesos.MariadbTask.handleHealthCheck(MariadbTask.java:310)
	at com.verizon.mesos.MariadbTask.executeCmd(MariadbTask.java:384)
	at com.verizon.mesos.MariadbTask.run(MariadbTask.java:450)
	at com.verizon.mesos.ExecutorTask.executeCmd(ExecutorTask.java:50)
	at com.verizon.mesos.ExecutorTask.run(ExecutorTask.java:115)
	at java.lang.Thread.run(Thread.java:745)


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