Enis Soztutar created HBASE-16095:
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Summary: Add priority to TableDescriptor and priority region open
thread pool
Key: HBASE-16095
URL: https://issues.apache.org/jira/browse/HBASE-16095
Project: HBase
Issue Type: Bug
Reporter: Enis Soztutar
Assignee: Enis Soztutar
Fix For: 2.0.0, 1.4.0
This is in the similar area with HBASE-15816, and also required with the
current secondary indexing for Phoenix.
The problem with P secondary indexes is that data table regions depend on index
regions to be able to make progress. Possible distributed deadlocks can be
prevented via custom RpcScheduler + RpcController configuration via HBASE-11048
and PHOENIX-938. However, region opening also has the same deadlock situation,
because data region open has to replay the WAL edits to the index regions.
There is only 1 thread pool to open regions with 3 workers by default. So if
the cluster is recovering / restarting from scratch, the deadlock happens
because some index regions cannot be opened due to them being in the same queue
waiting for data regions to open (which waits for RPC'ing to index regions
which is not open). This is reproduced in almost all Phoenix secondary index
clusters (mutable table w/o transactions) that we see.
The proposal is to have a "high priority" region opening thread pool, and have
the HTD carry the relative priority of a table. This maybe useful for other
"framework" level tables from Phoenix, Tephra, Trafodian, etc if they want some
specific tables to become online faster.
As a follow up patch, we can also take a look at how this priority information
can be used by the rpc scheduler on the server side or rpc controller on the
client side, so that we do not have to set priorities manually per-operation.
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