[jira] [Commented] (BOOKKEEPER-178) Delay ledger directory creation until the ledger index file was created

["Sijie Guo (Commented) (JIRA)" <ji...@apache.org>]

    [ https://issues.apache.org/jira/browse/BOOKKEEPER-178?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13215441#comment-13215441 ] 

Sijie Guo commented on BOOKKEEPER-178:
--------------------------------------

we did a simple performance testing comparing non-delay-dir-creation and delay-dir-creation.

3 bookie server, ensemble size 3, quorum size 2:

test steps:
1) create {num} ledgers
2) add 2 * {num} message to these ledgers in round-robin way (so a new message of each ledger would be added to each bookie server)
3) compute the throughput number

the result is shown as below

||num|| 1,000 || 10,000 || 100,000 || 1,000,000 ||
| non-delay-dir-creation | 3,154.57 | 4,564.71 | 4,618.40 | 10,468.79 | 
| delay-dir-creation | 4,219.41 | 7,401.92 | 16,636.17 | 18,267.00 |
                
> Delay ledger directory creation until the ledger index file was created
> -----------------------------------------------------------------------
>
>                 Key: BOOKKEEPER-178
>                 URL: https://issues.apache.org/jira/browse/BOOKKEEPER-178
>             Project: Bookkeeper
>          Issue Type: Improvement
>          Components: bookkeeper-server
>    Affects Versions: 4.0.0
>            Reporter: Sijie Guo
>            Assignee: Sijie Guo
>             Fix For: 4.1.0
>
>         Attachments: BK-178.patch
>
>
> The index file creation is delayed until absolutely necessary after BOOKKEEPER-137. but we don't delay the creation of parent directories of index file, it would hurt performance.

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