Details
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Sub-task
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Status: Open
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Major
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Resolution: Unresolved
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None
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Description
Today Drill uses ZooKeeper (ZK) to advertise the existence of a Drill-bit, providing the host name/IP Address of the Drill-bit and the ports used, encoded in Protobuf format. All other information (status, CPUs, memory) are assumed to be the same across all Drill-bits in the cluster as specified in the Drill config file. (Amended to reflect 1.6 behavior.)
Moving forward, as Drill becomes more sophisticated, Drill should advertise the specifics of each Drill-bit so that one Drill bit can differ from another.
For example, when running on YARN, we need a way for Drill to gracefully shut down. Advertising a status of Ready or Unavailable will help. Ready is the normal state. Unavailable means the Drill-bit will finish in-flight queries, but won't accept new ones. (The actual status is a separate enhancement.)
In a YARN cluster, Drill should take advantage of machines with more memory, but live with machines with less. (Perhaps some are newer, some are older or more heavily loaded.) Drill should use ZK to identify its available memory and CPUs so that the planner can use them. (Use of the info is a separate enhancement.)
There may be times when two drill bits run on a single machine. If so, they must use separate ports. So, each Drill-bit should advertise its ports in ZK.
For backward compatibility, the information is optional; if not present, the receiver should assume the information defaults to that in the config file.