[jira] Issue Comment Edited: (CASSANDRA-483) clean up bootstrap code, 2

["Jonathan Ellis (JIRA)" <ji...@apache.org>]

    [ https://issues.apache.org/jira/browse/CASSANDRA-483?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=12770203#action_12770203 ] 

Jonathan Ellis edited comment on CASSANDRA-483 at 10/27/09 3:06 AM:
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05
    refactor bootstrap to only concern itself with bootstrapping the local node, which greatly simplifies things

04
    rename getRangeMap -> getRangeAddresses; add inverse getAddressRanges

03
    fix the bootstrap interaction with gossip; there were two main problems:
    1) token and bootstrap state are not guaranteed to be gossiped together; since we only updated
    TMD.bootstrapNodes on an update of the token, this means we could actually miss the bootstrap notice
    2) deletions of state are not actually supported by Gossiper; there is no concept of that at the protocol
    level. so if we delete state locally it will never get gossiped. Instead, we have a MODE that is either
    MOVING or NORMAL, corresponding to bootstrap & normal operation.

02
    rename away underscores

01
    r/m single-use executor in favor of a Thread


      was (Author: jbellis):
    also fixes the bootstrap interaction with gossip; there were two main problems:

1) token and bootstrap state are not guaranteed to be gossiped together; since we only updated TMD.bootstrapNodes on an update of the token, this means we could actually miss the bootstrap notice
2) deletions of state are not actually supported by Gossiper; there is no concept of that at the protocol level.  so if we delete state locally it will never get gossiped.  Instead, we have a MODE that is either MOVING or NORMAL, corresponding to bootstrap & normal operation.  (Sandeep had it working like this in his initial bootstrap patches and I led him astray, sorry. :)

  
> clean up bootstrap code, 2
> --------------------------
>
>                 Key: CASSANDRA-483
>                 URL: https://issues.apache.org/jira/browse/CASSANDRA-483
>             Project: Cassandra
>          Issue Type: Improvement
>          Components: Tools
>            Reporter: Jonathan Ellis
>            Assignee: Jonathan Ellis
>             Fix For: 0.5
>
>         Attachments: 0001-CASSANDRA-483-r-m-single-use-executor-in-favor-of-a-Th.txt, 0002-rename-away-underscores.txt, 0003-fix-the-bootstrap-interaction-with-gossip-there-were.txt, 0004-rename-getRangeMap-getRangeAddresses-add-inverse-g.txt, 0005-refactor-bootstrap-to-only-concern-itself-with-bootstr.txt
>
>
> existing bootstrap code overengineers things a bit by allowing multiple nodes to bootstrap into the same span of the ring simultaneously.  but, this doesn't handle the case where one of them doesn't complete the bootstrap.  one possible response would be to transfer that node's span to one of the other new nodes, but then you're no longer evenly dividing the ring.  starting over with recomputed tokens for the remaining nodes is significantly complicated.
> in short I think the right solution is to handle each node independently.   if only one node bootstraps into a ring segment at a time, nothing changes.  but if another node bootstraps in before the first finishes, we just say "okay" and send them each the data they would get _if it were the only node bootstrapping_.  So if one fails, we don't have to do any extra work.  If all succeed, the penalty is we transferred too much to some nodes but that will be taken care of by the existing cleanup compaction code.
> (this does mean that we can't automatically pick tokens while a bootstrap is in progress, though, or it will pick the same one for both, which is undesireable.  but saying "if you want to bootstrap multiple nodes into the same ring span at once, you have to manually specify the tokens" seems reasonable to me.  (especially since that was already the case under the old system, if you didn't want just random tokens.)

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