In high RPS environments, the default listen backlog is not sufficient, so
giving users the power to configure it is the right approach, especially
since it requires only minor modifications to the code.
The check was placed in a way that conflicted with the continue
statements used by the node hearth beat code later that needs to skip
the current node sometimes. Moved at the start of the function so that's
always executed.
The check was placed in a way that conflicted with the continue
statements used by the node hearth beat code later that needs to skip
the current node sometimes. Moved at the start of the function so that's
always executed.
This feature allows slaves to migrate to orphaned masters (masters
without working slaves), as long as a set of conditions are met,
including the fact that the migrating slave needs to be in a
master-slaves ring with at least another slave working.
This feature allows slaves to migrate to orphaned masters (masters
without working slaves), as long as a set of conditions are met,
including the fact that the migrating slave needs to be in a
master-slaves ring with at least another slave working.
When we schedule a failover, broadcast a PONG to the slaves.
The other slaves that plan to get elected will do the same too, this way
it is likely that every slave will have a good picture of its own rank.
Note that this is N*N messages where N is the number of slaves for the
failing master, however usually even large clusters have many master
nodes but a limited number of replicas per node, so this is harmless.
When we schedule a failover, broadcast a PONG to the slaves.
The other slaves that plan to get elected will do the same too, this way
it is likely that every slave will have a good picture of its own rank.
Note that this is N*N messages where N is the number of slaves for the
failing master, however usually even large clusters have many master
nodes but a limited number of replicas per node, so this is harmless.
Note that when we compute the initial delay, there are probably still
more up to date information to receive from slaves with new offsets, so
the delay is recomputed when new data is available.
Note that when we compute the initial delay, there are probably still
more up to date information to receive from slaves with new offsets, so
the delay is recomputed when new data is available.
Return the number of slaves for the same master having a better
replication offset of the current slave, that is, the slave "rank" used
to pick a delay before the request for election.
Return the number of slaves for the same master having a better
replication offset of the current slave, that is, the slave "rank" used
to pick a delay before the request for election.
Accessing to the 'myself' node, the node representing the currently
running instance, is handy without the need to type
server.cluster->myself every time.
Accessing to the 'myself' node, the node representing the currently
running instance, is handy without the need to type
server.cluster->myself every time.
The two fields are used in order to remember the latest known
replication offset and the time we received it from other slave nodes.
This will be used by slaves in order to start the election procedure
with a delay that is proportional to the rank of the slave among the
other slaves for this master, when sorted for replication offset.
Usually this allows the slave with the most updated offset to win the
election and replace the failing master in the cluster.
The two fields are used in order to remember the latest known
replication offset and the time we received it from other slave nodes.
This will be used by slaves in order to start the election procedure
with a delay that is proportional to the rank of the slave among the
other slaves for this master, when sorted for replication offset.
Usually this allows the slave with the most updated offset to win the
election and replace the failing master in the cluster.
