Viraj Jasani created HBASE-26459:
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Summary: HMaster should move non-meta region only if meta is ONLINE
Key: HBASE-26459
URL: https://issues.apache.org/jira/browse/HBASE-26459
Project: HBase
Issue Type: Improvement
Affects Versions: 1.7.1
Reporter: Viraj Jasani
Fix For: 1.7.2
Any non-meta region movement has dependency over meta's availability, hence it
is important for any non-meta region to wait for meta to be assigned and be
available for scan before attempting to move non-meta region.
This concept has already been well managed by SCP (ServerCrashProcedure) on
HBase 1.x and 2.x versions. However, for 1.x versions, HMaster#move API doesn't
check for any prerequisite of meta being available before attempting to move
any non-meta region.
On the other hand, 2.x versions already have TransitRegionStateProcedure (TRSP)
in place that uses lock _LockState.LOCK_EVENT_WAIT_ in case if meta is not yet
assigned and loaded in AssignmentManager's memory:
{code:java}
@Override
protected boolean waitInitialized(MasterProcedureEnv env) {
if (TableName.isMetaTableName(getTableName())) {
return false;
}
// First we need meta to be loaded, and second, if meta is not online then we
will likely to
// fail when updating meta so we wait until it is assigned.
AssignmentManager am = env.getAssignmentManager();
return am.waitMetaLoaded(this) || am.waitMetaAssigned(this, getRegion());
}
{code}
For 1.x versions, it is recommended to introduce configurable wait time in
master's region move API for non-meta region movement until meta region is
available. If meta remains in transition after the wait time elapses, we should
fail fast and avoid non-meta region move.
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