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From "Suresh Srinivas (JIRA)" <j...@apache.org>
Subject [jira] [Commented] (HADOOP-9688) Add globally unique Client ID to RPC requests
Date Wed, 10 Jul 2013 23:59:49 GMT

    [ https://issues.apache.org/jira/browse/HADOOP-9688?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13705253#comment-13705253

Suresh Srinivas commented on HADOOP-9688:

bq. storageIDs are unique. There is now probability they will collide as far as I remember.
I am saying we can do the same for clientID.
The probability of StorageID collision is also non-zero. I am not sure how you can assert
otherwise. If you see the randomUUID method implementation, it also uses SecureRandom class.
Also unlike storageID, UUID are compact and 16 bytes.

bq. You know in big clusters most improbable events happen all the time.
I think this improbable even can also happen for StorageID.

Unlike StorageID, retry has many things that further reduce the probability:
# The clientID + callID is used only for retried requests. See the HADOP-9717.
# The validity of an entry in retry cache is short.

> Add globally unique Client ID to RPC requests
> ---------------------------------------------
>                 Key: HADOOP-9688
>                 URL: https://issues.apache.org/jira/browse/HADOOP-9688
>             Project: Hadoop Common
>          Issue Type: Improvement
>          Components: ipc
>            Reporter: Suresh Srinivas
>            Assignee: Suresh Srinivas
>            Priority: Blocker
>             Fix For: 3.0.0
>         Attachments: HADOOP-9688.clientId.1.patch, HADOOP-9688.clientId.patch, HADOOP-9688.patch
> This is a subtask in hadoop-common related to HDFS-4942 to add unique request ID to RPC

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