Re: duplicate processes

[Jussi Ramo <jussi.ramo@ericsson.com>]

 >What evidence do you have that the processes are started directly by 
init? Remember that a process will be inherited by init if its direct 
 >parent dies.

No evidence. Just looked at the parent process. So you suggest that the 
"runsv ndb_mgmd" dies and the ndb_mgmd is inherited by init. Then "runsv 
ndb_mgmd" is respawned by runsvdir (?) and that starts another ndb_mgmd. 
This makes sense to me but now the question is why runsv first dies once 
for certain processes.




 >> So duplicate process will be generated and system becomes unstable. 
Both of those processes (the one started by init and the one started by 
runsv) react on sv command.
 >React in what ways?

Do not know if this brings any extra information but if I have first the 
following ndb_mgmd processes (one of them badly as child of init) :

root      1950  1945  0 07:04 ?        00:00:00 runsv ndb_mgmd
ais       1963     1  0 07:04 ?        00:00:00 /opt/SGC/bin/ndb_mgmd -f 
/opt/SGC/etc/ndbconfig.ini
ais       2276  1950  2 07:05 ?        00:00:00 /opt/SGC/bin/ndb_mgmd -f 
/opt/SGC/etc/ndbconfig.ini

Then I do like:

blade_0_7:~ # /opt/SGC/bin/sv down /var/services/ndb_mgmd/

and the other "right" ndb_mgmd disappears:

root      1950  1945  0 07:04 ?        00:00:00 runsv ndb_mgmd
ais       1963     1  0 07:04 ?        00:00:00 /opt/SGC/bin/ndb_mgmd -f 
/opt/SGC/etc/ndbconfig.ini

I then kill the "wrong" ndb_mgmd

blade_0_7:~ # kill -9 1963
root      1950  1945  0 07:04 ?        00:00:00 runsv ndb_mgmd

And when ndb_mgmd is put "up" there are again those two processes:

blade_0_7:~ # /opt/SGC/bin/sv up /var/services/ndb_mgmd/

root      1950  1945  0 07:04 ?        00:00:00 runsv ndb_mgmd
ais       2805     1  0 07:08 ?        00:00:00 /opt/SGC/bin/ndb_mgmd -f 
/opt/SGC/etc/ndbconfig.ini
ais       2837  1950  4 07:08 ?        00:00:00 /opt/SGC/bin/ndb_mgmd -f 
/opt/SGC/etc/ndbconfig.ini


 >> For example below: aisexec works properly but ndb_mgmd causes problems.
 >Google tells me that ndb_mgmd is part of mysql. mysql is known to be 
badly designed wrt co-operating with runit/daemontools.

This is a good piece of information. Other 3pp product that causes similar 
troubles as mysql to me is EMANATE snmp agent, when using with runit.


 >> There are no major diffrencies in run scripts but file paths or so. 
Both of the run scrips are quite simple.
 >What are they?

#!/bin/sh
# Source environment settings
. /opt/SGC/etc/sgcenv
exec >> $LOG_FILE 2>&1
aisexec_BIN=/opt/SGC/bin/aisexec
exec $aisexec_BIN


#!/bin/sh
# Source environment settings
. /opt/SGC/etc/sgcenv
exec >> $LOG_FILE 2>&1
ndb_mgmd_BIN=/opt/SGC/bin/ndb_mgmd
exec $ndb_mgmd_BIN -f /opt/SGC/etc/ndbconfig.ini



 >> The other ndb_mgmd is restarted frequently by runsv because of the 
same process is started directly by init for some reason.
 >Again, what evidence do you have that there is any process started 
directly by init? Even if so, why would runsv restart the process it is 
managing? I expect that the process runsv is monitoring is exiting, and 
that is why runsv is starting a new process.

Right. The process runsv is monitoring is exiting because the port it 
tries to use is reserved by the extra process (now hopefully correct 
phrasing:) whose parent is init.

Thanks and regards,
Jussi

P.S. I now tried to create a new message for a mailing thread, first time 
I just replied on an existing thread changing the subject. Sorry for that!