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https://issues.apache.org/jira/browse/DERBY-3527?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
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Jørgen Løland updated DERBY-3527:
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Attachment: derby-3527-1a.stat
derby-3527-1a.diff
Patch 1a checks if the network connection is up by sending a ping message from
the slave to the master. The shipment of the message has to happen in a
separate thread because TCP timeout for send message is 2 minutes, not
configurable. Also added a message reader thread on the master that currently
accepts two kinds of messages: ping and ack. This receiver thread should later
be modified to also accept other messages from the slave - like "slave is
stopped due to a system shutdown".
I have tested the patch by hand on two computers. I have tried to pull the
plug, and this patch fixes the reported problem (i.e., failover after pulled
plug is accepted only with the patch applied). The replication test suite
passed; currently running the other tests.
Requesting review.
> 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
>
>
> 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.
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