MySQL Bugs: #43051: agent blocks session, cannot logout from it after starting agent

Bug #43051	agent blocks session, cannot logout from it after starting agent
Submitted:	20 Feb 2009 9:35	Modified:	6 May 2010 10:06
Reporter:	Carsten Segieth	Email Updates:
Status:	Closed	Impact on me:	None
Category:	MySQL Enterprise Monitor: Agent	Severity:	S2 (Serious)
Version:	2.0.4.7139, 2.2.0.1666	OS:	Any
Assigned to:	Michael Schuster	CPU Architecture:	Any

Description:
After starting the agent one can no longer logout from the session where the agent was started.

Tested on 5 different OS, so it looks to be a general problem that was introduced between 2.0.4.7138 and 2.0.4.7139.

Using build 7138 one can logout without problems after the agent was started. With all builds since 7139 one cannot logout (it hangs) and need to kill the session where the agent start command was issued.

How to repeat:
test both with 2.0.4.7138 (logout works fine) and 2.0.4.7139 (logout 'hanging')
- ssh to any system
- start agent using the etc/ini.d/ script
- try to logout from the ssh session after agent was started

Suggested fix:
make it work as before ...

there was no code change between 7138 and 7139 in the 2.0 branch.

I was able to consistently verify this behavior on 'blade01'.

Is this related to the fix for Bug #40583?

reproduced on blade01 with the steps from above with build 2.0.5.7151 (where 7138 works)

Change incorporated into version 2.0.5.7152. Agreed to work as expected on 'blade01'. However other platforms need to be tested.

2.0.5.7152 on qa-merlin shows for "restart" if no server was running before (7151 does not show this):
...
cat: /tmp/xfile.8708: No such file or directory
etc/init.d/mysql-monitor-agent: line 231: test: -eq: unary operator expected
...

2.0.5.7152 - using 'restart' to start the agent (to check the script for a non running agent), these (and similar) messages are shown on different OS:

cat: /tmp/xfile.21290: No such file or directory
etc/init.d/mysql-monitor-agent: line 231: test: -eq: unary operator expected

cat: /tmp/xfile.28260: No such file or directory
test: -eq: unexpected operator

cat: cannot open /tmp/xfile.245
etc/init.d/mysql-monitor-agent: test: argument expected

cat: /tmp/xfile.10877: No such file or directory
etc/init.d/mysql-monitor-agent: line 231: test: -eq: unary operator expected

cat: 0652-050 Cannot open /tmp/xfile.1015848.
etc/init.d/mysql-monitor-agent[231]: test: 0403-004 Specify a parameter with this command.

2.0.5.7153 - I still see the blocking when working with remote ssh, but the messages are gone:

pino@IBM /cygdrive/d/Merlin/inst/agent
$ CMD=restart ; V=2.0.3.7134; net-qa1 /data0/merlin/agent/${V}/rhel4-x86-32bit/net-qa1/etc/init.d/mysql-monitor-agent $CMD /data0/merlin/agent/${V}/r
hel4-x86-32bit/net-qa1/etc/no_ssl_quan.ini
MySQL Enterprise agent PID file could not be found![FAILED]
Starting MySQL Enterprise agent service...[  OK  ]

pino@IBM /cygdrive/d/Merlin/inst/agent
$ CMD=stop    ; V=2.0.3.7134; net-qa1 /data0/merlin/agent/${V}/rhel4-x86-32bit/net-qa1/etc/init.d/mysql-monitor-agent $CMD /data0/merlin/agent/${V}/r
hel4-x86-32bit/net-qa1/etc/no_ssl_quan.ini
Shutting down MySQL Enterprise agent service.......[  OK  ]

pino@IBM /cygdrive/d/Merlin/inst/agent
$ CMD=restart ; V=2.0.5.7151   ; net-qa1 /data0/merlin/agent/${V}/rhel4-x86-32bit/net-qa1/etc/init.d/mysql-monitor-agent $CMD /data0/merlin/agent/${V
}/rhel4-x86-32bit/net-qa1/etc/no_ssl_quan.ini
MySQL Enterprise agent PID file could not be found![FAILED]
Starting MySQL Enterprise agent service...[  OK  ]
Killed by signal 2.

pino@IBM /cygdrive/d/Merlin/inst/agent

Seen in version 2.0.5.7153

Another possible workaround: start the agent from screens

Diego Medina writes: 
To make sure you see this error, please use the init.d script that comes with the installer. There are times when the init.d script that we have in our branch is not what customers (or QA) end up using.

Keith Russell writes: 
Patch installed in versions => 2.2.0.1705.

Carsten Segieth writes: 
tested OK in build 2.2.0.1705

A note has been added to the 2.2.0 changelog