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https://issues.apache.org/jira/browse/HDFS-12682?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
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Xiao Chen updated HDFS-12682:
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Attachment: HDFS-12682.03.patch
Thanks for the review Eddy!
Had some offline discussions with Eddy to clarify his second point. His
proposal is we do not change the protobuf, but handles it carefully so the
state is only exposed to the -listPolicies.
Attached patch 3 which implements this idea. The advantage of this is:
- compatible, so less intrusive
- less code change
- no ECPInfo class/proto, which just contain the same information of the
current ECP.
The drawback is:
- Converting to protobuf need to be overloaded to handle with state, and
without state. Added some javadoc to hopefully make it clear.
- since the ECP object will always have the state, so for calls other than
-listPolicies, the object will have a state to DISABLED (the default).
Considering we make the ECP class {{InterfaceAudience.Private}}, this is within
HDFS and should be okay.
> ECAdmin -listPolicies will always show policy state as DISABLED
> ---------------------------------------------------------------
>
> Key: HDFS-12682
> URL: https://issues.apache.org/jira/browse/HDFS-12682
> Project: Hadoop HDFS
> Issue Type: Bug
> Components: erasure-coding
> Reporter: Xiao Chen
> Assignee: Xiao Chen
> Priority: Blocker
> Labels: hdfs-ec-3.0-must-do
> Attachments: HDFS-12682.01.patch, HDFS-12682.02.patch,
> HDFS-12682.03.patch
>
>
> On a real cluster, {{hdfs ec -listPolicies}} will always show policy state as
> DISABLED.
> {noformat}
> [hdfs@nightly6x-1 root]$ hdfs ec -listPolicies
> Erasure Coding Policies:
> ErasureCodingPolicy=[Name=RS-10-4-1024k, Schema=[ECSchema=[Codec=rs,
> numDataUnits=10, numParityUnits=4]], CellSize=1048576, Id=5, State=DISABLED]
> ErasureCodingPolicy=[Name=RS-3-2-1024k, Schema=[ECSchema=[Codec=rs,
> numDataUnits=3, numParityUnits=2]], CellSize=1048576, Id=2, State=DISABLED]
> ErasureCodingPolicy=[Name=RS-6-3-1024k, Schema=[ECSchema=[Codec=rs,
> numDataUnits=6, numParityUnits=3]], CellSize=1048576, Id=1, State=DISABLED]
> ErasureCodingPolicy=[Name=RS-LEGACY-6-3-1024k,
> Schema=[ECSchema=[Codec=rs-legacy, numDataUnits=6, numParityUnits=3]],
> CellSize=1048576, Id=3, State=DISABLED]
> ErasureCodingPolicy=[Name=XOR-2-1-1024k, Schema=[ECSchema=[Codec=xor,
> numDataUnits=2, numParityUnits=1]], CellSize=1048576, Id=4, State=DISABLED]
> [hdfs@nightly6x-1 root]$ hdfs ec -getPolicy -path /ecec
> XOR-2-1-1024k
> {noformat}
> This is because when [deserializing
> protobuf|https://github.com/apache/hadoop/blob/branch-3.0.0-beta1/hadoop-hdfs-project/hadoop-hdfs-client/src/main/java/org/apache/hadoop/hdfs/protocolPB/PBHelperClient.java#L2942],
> the static instance of [SystemErasureCodingPolicies
> class|https://github.com/apache/hadoop/blob/branch-3.0.0-beta1/hadoop-hdfs-project/hadoop-hdfs-client/src/main/java/org/apache/hadoop/hdfs/protocol/SystemErasureCodingPolicies.java#L101]
> is first checked, and always returns the cached policy objects, which are
> created by default with state=DISABLED.
> All the existing unit tests pass, because that static instance that the
> client (e.g. ECAdmin) reads in unit test is updated by NN. :)
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