db-derby-dev mailing list archives

Site index · List index
Message view « Date » · « Thread »
Top « Date » · « Thread »
From Øystein Grøvlen (JIRA) <j...@apache.org>
Subject [jira] Commented: (DERBY-3527) The slave will not notice that a network cable is unplugged and will therefore reject failover/stopSlave commands
Date Mon, 31 Mar 2008 10:24:24 GMT

    [ https://issues.apache.org/jira/browse/DERBY-3527?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=12583622#action_12583622
] 

Øystein Grøvlen commented on DERBY-3527:
----------------------------------------

Thanks, Jørgen. I think the changes on the master side looks good.
I am still trying to understand the issues around synchronization in ReplicationMessageReceive.

I wonder whether the following scenario could occur: isConnectedToMaster is called. Thread
notifies ping thread which sends ping, but when it is to get the receivePongSemaphore, it
has already been acquired by readMessage which reads the pong and calls notify before the
isConnectedToMaster has started to wait. I think this could lead to a false conclusion that
the master is down.

> The slave will not notice that a network cable is unplugged and will therefore reject
failover/stopSlave commands
> -----------------------------------------------------------------------------------------------------------------
>
>                 Key: DERBY-3527
>                 URL: https://issues.apache.org/jira/browse/DERBY-3527
>             Project: Derby
>          Issue Type: Bug
>          Components: Replication
>    Affects Versions: 10.4.0.0, 10.5.0.0
>            Reporter: Jørgen Løland
>            Assignee: Jørgen Løland
>         Attachments: derby-3527-1a.diff, derby-3527-1a.stat, derby-3527-1b.diff, derby-3527-1b.stat,
derby-3527-1c.diff, derby-3527-1c.stat
>
>
> If a network cable between the master and slave is unplugged (or a switch crashes etc),
ObjectInputStream#readObject will not get an exception. Neither the socket nor the input stream
can be queried for information on whether or not the connection is working. AFAIK, the only
way to find out if the network is down is to send a message.
> The slave commands stopSlave and failover are rejected if the network connection is working.
To be absolutely sure that the connection is working, we need to ping the master when these
commands are requested.

-- 
This message is automatically generated by JIRA.
-
You can reply to this email to add a comment to the issue online.


Mime
View raw message