[jira] [Created] (HBASE-15327) Canary will always invoke admin.balancer() in each sniffing period when writeSniffing is enabled

["Jianwei Cui (JIRA)" <ji...@apache.org>]

Jianwei Cui created HBASE-15327:
-----------------------------------

             Summary: Canary will always invoke admin.balancer() in each sniffing period when writeSniffing is enabled
                 Key: HBASE-15327
                 URL: https://issues.apache.org/jira/browse/HBASE-15327
             Project: HBase
          Issue Type: Bug
          Components: canary
    Affects Versions: 2.0.0
            Reporter: Jianwei Cui
            Priority: Minor


When Canary#writeSniffing is enabled, Canary#checkWriteTableDistribution will make sure the regions of write table distributed on all region servers as:
{code}
      int numberOfServers = admin.getClusterStatus().getServers().size();
      ......
      int numberOfCoveredServers = serverSet.size();
      if (numberOfCoveredServers < numberOfServers) {
        admin.balancer();
      }
{code}
The master will also work as a regionserver, so that ClusterStatus#getServers will contain the master. On the other hand, write table of Canary will not be assigned to master, making numberOfCoveredServers always smaller than numberOfServers and admin.balancer always be invoked in each sniffing period. This may cause frequent region moves. A simple fix is excluding master from numberOfServers.



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