private ProcessorEntity getLeader(String jmv) {
    for (ProcessorEntity entity: table.getEntitiesWithPartition(jmv)) {
      if (entity.getIsLeader()) return entity;
    }
    return null;
  }
Scheduler class invoked by each processor to check if the leader is alive.
Checks every 30 seconds.
If a processor row hasn't been updated since 30 seconds, the system assumes that the processor has died.
All time units are in SECONDS.
samza-azure/src/main/java/org/apache/samza/coordinator/scheduler/LeaderLivenessCheckScheduler.java