Hbase master failed to start with error "java.io.IOException: Timedout 300000ms waiting for namespace table to be assigned"

Symptom:

Hbase master failed to start with error "java.io.IOException: Timedout 300000ms waiting for namespace table to be assigned".

It could happen when starting or switching to master. 

Sample error messages are:

2000-01-01 01:01:01,999 FATAL [myhost:16000.activeMasterManager] master.HMaster: Unhandled exception. Starting shutdown.
java.io.IOException: Timedout 300000ms waiting for namespace table to be assigned
    at org.apache.hadoop.hbase.master.TableNamespaceManager.start(TableNamespaceManager.java:104)
    at org.apache.hadoop.hbase.master.HMaster.initNamespace(HMaster.java:1005)
    at org.apache.hadoop.hbase.master.HMaster.finishActiveMasterInitialization(HMaster.java:799)
    at org.apache.hadoop.hbase.master.HMaster.access$500(HMaster.java:191)
    at org.apache.hadoop.hbase.master.HMaster$1.run(HMaster.java:1783)
    at java.lang.Thread.run(Thread.java:745)

Or

2000-01-01 01:01:01,999 FATAL [myhost:16000.activeMasterManager] master.HMaster: Failed to become active master
java.io.IOException: Timedout 300000ms waiting for namespace table to be assigned
    at org.apache.hadoop.hbase.master.TableNamespaceManager.start(TableNamespaceManager.java:104)
    at org.apache.hadoop.hbase.master.HMaster.initNamespace(HMaster.java:1005)
    at org.apache.hadoop.hbase.master.HMaster.finishActiveMasterInitialization(HMaster.java:799)
    at org.apache.hadoop.hbase.master.HMaster.access$500(HMaster.java:191)
    at org.apache.hadoop.hbase.master.HMaster$1.run(HMaster.java:1783)
    at java.lang.Thread.run(Thread.java:745)

Env:

hbase 1.1.8

Root Cause:

When Hbase master is starting, it assigns meta table firstly and then assign other tables.

So hbase:namespace is the same as other tables in this assignment phase.

If there are too many tables or regions, and the default 300000ms(5mins) may not be enough.

Solution:

Increase hbase.master.namespace.init.timeout in hbase-site.xml and restart Hbase Master.