In some cases, like read more than write scenario, the replication
offset of the replicas are the same. When the primary fails, the
replicas have the same rankings (rank == 0). They issue the election
at the same time (although we have a random 500), the simultaneous
elections may lead to the failure of the election due to quorum.
In clusterGetReplicaRank, when we calculates the rank, if the offsets
are the same, the one with the smaller node name will have a better
rank to avoid this situation.
---------
Signed-off-by: Binbin <binloveplay1314@qq.com>
This commit adds a logic to cache `CLUSTER SLOTS` response for reduced
latency and also updates the cache when a change in the cluster is
detected.
Historically, `CLUSTER SLOTS` command was deprecated, however all the
server clients have been using `CLUSTER SLOTS` and have not migrated to
`CLUSTER SHARDS`. In future this logic can be added to any other
commands to improve the performance of the engine.
---------
Signed-off-by: Roshan Khatri <rvkhatri@amazon.com>
We currently has two disjoint TCL frameworks:
1. Normal testing framework, which trigger by runtest, which individually
launches nodes for testing.
2. Cluster framework, which trigger by runtest-cluster, which pre-allocates
N nodes and uses them for testing large configurations.
The normal TCL testing framework is much more readily tested and is also
automatically run as part of the CI for new PRs. The runtest-cluster since
it runs very slowly (cannot be parallelized), it currently only runs in daily
CI, this results in some changes to the cluster not being exposed in PR CI
in time.
This PR migrate the Cluster mode tests to normal framework. Some cluster
tests are kept in runtest-cluster because of timing issues or not yet
supported, we can process them later.
Signed-off-by: Binbin <binloveplay1314@qq.com>
