@InterfaceAudience.Private

Package org.apache.hadoop.hdfs.server.namenode.startupprogress

This package provides a mechanism for tracking NameNode startup progress.

See: Description

Package org.apache.hadoop.hdfs.server.namenode.startupprogress Description

This package provides a mechanism for tracking NameNode startup progress. The package models NameNode startup as a series of Phases, with each phase further sub-divided into multiple Steps. All phases are coarse-grained and typically known in advance, implied by the structure of the NameNode codebase (example: loading fsimage). Steps are more granular and typically only known at runtime after startup begins (example: loading a specific fsimage file with a known length from a particular location). StartupProgress provides a thread-safe data structure for recording status information and counters. Various parts of the NameNode codebase use this to describe the NameNode's activities during startup. StartupProgressView provides an immutable, consistent view of the current state of NameNode startup progress. This can be used to present the data to a user. StartupProgressMetrics exposes startup progress information via JMX through the standard metrics system.

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