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https://issues.apache.org/jira/browse/HDFS-11804?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
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Rushabh S Shah updated HDFS-11804:
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Attachment: HDFS-11804-trunk.patch
This is by no means a committable patch.
It needs some rework.
Changes done in this patch:
1. Only LoadBalancingKMSClientProvider will be instantiated when createProvider
is being called.
2. Added three new config keys similar to dfs client.
* {{kms.client.failover.attempts.multiplier}}: This is the multiplier factor.
For example: if {{kms.client.failover.attempts.multiplier}} is 2 and there are
2 backend kms servers, then client will retry for maximum 4 times.
* {{kms.client.failover.sleep.base.millis}}: To calculate failover sleep time.
* {{kms.client.failover.sleep.max.millis}}: To calculate maximum amount of time
to sleep.
3. The client is configured to use {{FailoverOnNetworkExceptionRetry}} with
fallback policy as {{TryOnceThenFail}}.
On encountering AccessControlException or AuthorizationException, the client
will stop retrying. This assumes all the servers are configured with identical
permissions and key acls.
4. Since the {{RetryPolicy#shouldRetry}} function expects whether the option is
idempotent or not, We need to decide what all operations are idempotent.
Below is my understanding.
** IdempotentOperations: renewDelegationToken, cancelDelegationToken,
decryptEncryptedKey, getKeyVersion, getKeys, getKeysMetadata, getKeyVersions,
getCurrentKey, getMetadata
** AtMostOnce: createKey, deleteKey, rollNewVersion
** Not sure: addDelegationTokens, generateEncryptedKey,
reencryptEncryptedKey
Would like to know your views.
There are few TODOs in the patch. Would like to know your opinions on that also.
Thanks in advance for reviewing my patch.
> KMS client needs retry logic
> ----------------------------
>
> Key: HDFS-11804
> URL: https://issues.apache.org/jira/browse/HDFS-11804
> Project: Hadoop HDFS
> Issue Type: Bug
> Affects Versions: 2.6.0
> Reporter: Rushabh S Shah
> Assignee: Rushabh S Shah
> Attachments: HDFS-11804-trunk.patch
>
>
> The kms client appears to have no retry logic – at all. It's completely
> decoupled from the ipc retry logic. This has major impacts if the KMS is
> unreachable for any reason, including but not limited to network connection
> issues, timeouts, the +restart during an upgrade+.
> This has some major ramifications:
> # Jobs may fail to submit, although oozie resubmit logic should mask it
> # Non-oozie launchers may experience higher rates if they do not already have
> retry logic.
> # Tasks reading EZ files will fail, probably be masked by framework reattempts
> # EZ file creation fails after creating a 0-length file – client receives
> EDEK in the create response, then fails when decrypting the EDEK
> # Bulk hadoop fs copies, and maybe distcp, will prematurely fail
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