MySQL Bugs: #5588: "Lost connection to MySQL server during query (server

Bug #5588	"Lost connection to MySQL server during query (server_errno=2013)" every hour
Submitted:	15 Sep 2004 9:25	Modified:	15 Sep 2005 19:28
Reporter:	Joerg Klein	Email Updates:
Status:	Closed	Impact on me:	None
Category:	MySQL Server: Replication	Severity:	S3 (Non-critical)
Version:	4.0.21	OS:	Windows (win2000)
Assigned to:		CPU Architecture:	Any

Description:
I have a two way replication on 2 servers. A<->B
On each server I have the following entry in the server.err file every hour, if there is no activity(processing queries) on it alternatively if the position of the log event is the same as one hour before:
-------------------------------------------------------------------------------
040915  9:36:49 Error reading packet from server: Lost connection to MySQL server during query (server_errno=2013)
040915  9:36:49 Slave I/O thread: Failed reading log event, reconnecting to retry, log 'obelix-bin.006' position 79
040915  9:36:49 Slave: connected to master 'repl@10.10.10.32:3306',replication resumed in log 'obelix-bin.006' at position 79
040915 10:36:50 Error reading packet from server: Lost connection to MySQL server during query (server_errno=2013)
040915 10:36:50 Slave I/O thread: Failed reading log event, reconnecting to retry, log 'obelix-bin.006' position 79
040915 10:36:50 Slave: connected to master 'repl@10.10.10.32:3306',replication resumed in log 'obelix-bin.006' at position 79
-------------------------------------------------------------------------------

This Error has no impact on the Replication. It works without problems.

How to repeat:
-

Suggested fix:
-

Hi,

Thanks for your bug report!

This is expected behavior.  This reconnection is due to the slave_timeout value which is set to
3600 seconds by default (1 hour).  This is in place because there are cases where the master 
may go down and come back up but the slave isn't notified so it stays in waiting on the same 
connection.  This timeout will cause a reconnection so that a new and working connection will be 
made.

Best Regards

OK, that's a good idea, but my eventlog and the *.err is full of these messages and it is more difficult to see if there is a 'real' error on the mysql server.

I would like to be emailed with the solution to this problem when a response is sent.

I agree with Joerg Klein. It's a nuisance to have these entries in the error log when they are not "real" errors. As a newbie to MySQL replication, where in the docs does it say to expect these "errors" and where does it say that they are not "errors"? I'm testing out replication and looking at my logs thinking, how do I fix this?

Hi,
The normal behaviour is indeed to not print any message in case of connection failure if this failure is because of timeout, which is apparently your case. Maybe something in the network layer (of MySQL or something else) fails to qualify the disconnection as due to timeout. It could be specific to Win2000 (on Linux for example, there is no such error message printed). We'll do one test on Win2000 to see if we can repeat.

Could you please provide your my.ini/my.cnf files for to make
the test on my side.

Thanks in advance.

I verified this on windows 2000 this way:

- start master and slave, both on Windows (2000 if possible, otherwise
any other Windows). Slave should be started with
--slave_net_timeout=1.

- Leave master idle.

- Verify that replication is running (SHOW SLAVE STATUS) and see if
your slave's error log gets filled with error messages.

- If no message, verify that slave I/O thread reconnects every second,
by monitoring SHOW PROCESSLIST on master (should display a new system
thread every second).

For the record, I'm marking here that this is verified on Win2000 and not on Linux: platform-specific MySQL bug.

A patch for this bug has been committed. After review, it may
be pushed to the relevant source trees for release in the next
version. You can access the patch from:

  http://lists.mysql.com/internals/28893

A patch for this bug has been committed. After review, it may
be pushed to the relevant source trees for release in the next
version. You can access the patch from:

  http://lists.mysql.com/internals/29030

Patch looks ok now.
Before pushing, please verify that this fixes the reported problem on windows. (See Matthew Lord's comment of how to do this)

A patch for this bug has been committed. After review, it may
be pushed to the relevant source trees for release in the next
version. You can access the patch from:

  http://lists.mysql.com/internals/29421

Fixed in 4.0.27, 4.1.15, 5.0.13

Noted in 4.0.27, 4.1.15, 5.0.13 changelogs.

Somewhat related: BUG#53955.

Similar error happened on Cent-OS and 5.5.3 version of mysql.

110722 21:31:57 [ERROR] Error reading packet from server: Lost connection to MySQL server during query ( server_errno=2013)
110722 21:31:57 [Note] Slave I/O thread: Failed reading log event, reconnecting to retry, log 'binary-logs.000525' at postion 458558
110722 21:31:57 [ERROR] Slave I/O: error reconnecting to master 'XXXXXXXX' - retry-time: 10  retries: 86400, Error_code: 2003