On 6/18/2015 2:10 PM, Ben RUBSON wrote:
Hello,
In order for the slave to quickly show a communication issue between
the master and the slave, I set slave_net_timeout to 10.
"show slave status" then quickly updates, perfect.
I would also like the master to quickly show when the slave is no more
reachable.
However, "show processlist" and "show slave hosts" take a very long
time to update their status when the slave has gone.
Is there any way to have a refresh rate of about 10 seconds, as I did
on slave side ?
Thank you !
Ben
There are two situations to consider
1) The slave is busy re-trying. It will do this a number of times then
eventually disconnect itself. If it does disconnect itself, the
processlist report will show it as soon as that happens.
2) The connection between the master and slave died (or the slave itself
is lost). In this case, the server did not receive any "I am going to
disconnect" message from its client (the slave). So as far as the server
is concerned, it is simply sitting in a wait expecting the client to
eventually send in a new command packet.
That wait is controlled by --wait-timeout. Once an idle client
connection hits that limit, the server is programmed to think "the idiot
on the other end of this call has hung up on me" so it simply closes its
end of the socket. There are actually two different timers that could be
used, --wait-timeout or --interactive-timeout and which one is used to
monitor the idle socket depends entirely on if the client did or did not
set the 'interactive flag' when it formed the connection. MySQL slaves
do not use that flag.
Now, if the line between the two systems died in the middle of a
conversation (an actual data transfer) then a shorter -net-write-timeout
or --net-read-timeout would expire and the session would die then. But I
think you were not observing one of those failures.
Does that help?
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Shawn Green
MySQL Senior Principal Technical Support Engineer
Oracle USA, Inc. - Hardware and Software, Engineered to Work Together.
Office: Blountville, TN
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