MySQL Bugs: #50797: Agent won't reconnect to monitored DB if started when monitored DB is down 2.1.1

Bug #50797	Agent won't reconnect to monitored DB if started when monitored DB is down 2.1.1
Submitted:	1 Feb 2010 18:38	Modified:	1 Mar 2010 13:45
Reporter:	Diego Medina	Email Updates:
Status:	Closed	Impact on me:	None
Category:	MySQL Enterprise Monitor: Agent	Severity:	S1 (Critical)
Version:	2.1.1.1138	OS:	Any
Assigned to:	Kay Roepke	CPU Architecture:	Any
Tags:	regression, windmill

Description:
If you start the mysqld server before starting the agent, the agent 2.1.1.1138 will never reconnect to the database.
This was fixed on 2.1.0.1074, and it is fixed on 2.2, but somehow 2.1.1.x does not have the fix.

How to repeat:
After you have the agent and mysqld all running and it all shows up on the 
dashboard.

2- stop the mysqld
3- wait until you see an error message on the agent log
4- start the mysqld
5- the agent will not try to reconnect to the mysqld server.

Diego Medina writes: 
On Mac OS 10.5 the agent does reconnect to the mysqld after one minute, the agent tries to reconnect to the mysqld once every minute.

{noformat}
2010-02-01 16:31:52: (critical) proxy-plugin.c.1539: Cannot connect, all backends are down.
2010-02-01 16:31:52: (critical) proxy-plugin.c.1539: Cannot connect, all backends are down.
2010-02-01 16:31:52: (critical) proxy-plugin.c.1539: Cannot connect, all backends are down.
2010-02-01 16:31:52: (critical) proxy-plugin.c.1539: Cannot connect, all backends are down.
2010-02-01 16:31:52: (critical) proxy-plugin.c.1539: Cannot connect, all backends are down.
2010-02-01 16:32:00: (critical) agent_mysqld.c:707: successfully connected to database at 127.0.0.1:5132 as user msandbox (with password: YES)
{noformat}

The messages 
(critical) proxy-plugin.c.1539: Cannot connect, all backends are down.
were because I was trying to send queries through the proxy port.

Kay Roepke writes: 
rats. I used the wrong issue number in the push (the original one instead of this one).
anyway, the two commits fix Bug#50797/EM-4008

Keith Russell writes: 
Patch installed in versions => 2.1.1.1144..

Diego Medina writes: 
Verified fixed on 2.1.1.1144 on mac os .
Waiting for Windows test

Diego Medina writes: 
adding Bill to QA

A note has been added to the 2.1.1 changelog: 

   The &merlin_agent; could fail to reconnect to a monitored MySQL instance if the agent was started while the MySQL instance was unavailable.