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https://issues.apache.org/jira/browse/BOOKKEEPER-432?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13508958#comment-13508958
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Hadoop QA commented on BOOKKEEPER-432:
--------------------------------------

Testing JIRA BOOKKEEPER-432

WARNING: Running test-patch on a dirty local svn workspace

Patch <a 
href="/jira/secure/attachment/12555803/PortSkipListLedgerStore.patch">/jira/secure/attachment/12555803/PortSkipListLedgerStore.patch</a>
 downloaded at Mon Dec  3 18:58:51 UTC 2012

----------------------------

{color:green}+1 PATCH_APPLIES{color}
{color:green}+1 CLEAN{color}
{color:red}-1 RAW_PATCH_ANALYSIS{color}
.    {color:green}+1{color} the patch does not introduce any @author tags
.    {color:red}-1{color} the patch contains 1 line(s) with tabs
.    {color:green}+1{color} the patch does not introduce any trailing spaces
.    {color:green}+1{color} the patch does not introduce any line longer than 
120
.    {color:green}+1{color} the patch does adds/modifies 7 testcase(s)
{color:green}+1 RAT{color}
.    {color:green}+1{color} the patch does not seem to introduce new RAT 
warnings
{color:red}-1 JAVADOC{color}
.    {color:red}-1{color} the patch seems to introduce 3 new Javadoc warning(s)
{color:green}+1 COMPILE{color}
.    {color:green}+1{color} HEAD compiles
.    {color:green}+1{color} patch compiles
.    {color:green}+1{color} the patch does not seem to introduce new javac 
warnings
{color:red}-1 FINDBUGS{color}
.    {color:red}-1{color} the patch seems to introduce 8 new Findbugs 
warning(s) in module(s) [bookkeeper-server]
{color:green}+1 TESTS{color}
.    Tests run: 393
{color:green}+1 DISTRO{color}
.    {color:green}+1{color} distro tarball builds with the patch 

----------------------------
{color:red}*-1 Overall result, please check the reported -1(s)*{color}


The full output of the test-patch run is available at

.   https://builds.apache.org/job/bookkeeper-trunk-precommit-build/71/
                
> Improve performance of entry log range read per ledger entries 
> ---------------------------------------------------------------
>
>                 Key: BOOKKEEPER-432
>                 URL: https://issues.apache.org/jira/browse/BOOKKEEPER-432
>             Project: Bookkeeper
>          Issue Type: Improvement
>          Components: bookkeeper-server
>    Affects Versions: 4.2.0
>         Environment: Linux
>            Reporter: Yixue (Andrew) Zhu
>            Assignee: Yixue (Andrew) Zhu
>              Labels: patch
>         Attachments: BookieLedgerStorageProposal.pdf, 
> PortSkipListLedgerStore.patch
>
>
> We observed random I/O reads when some subscribers fall behind (on some 
> topics), as delivery needs to scan the entry logs (thru ledger index), which 
> are interleaved with ledger entries across all ledgers being served.
> Essentially, the ledger index is a non-clustered index. It is not effective 
> when a large number of ledger entries need to be served, which tend to be 
> scattered around due to interleaving.
> Some possible improvements:
> 1. Change the ledger entries buffer to use a SkipList (or other suitable), 
> sorted on (ledger, entry sequence). When the buffer is flushed, the entry log 
> is written out in the already-sorted order. 
> The "active" ledger index can point to the entries buffer (SkipList), and 
> fixed up with entry-log position once latter is persisted.
> Or, the ledger index can be just rebuilt on demand. The entry log file tail 
> can have index attached (light-weight b-tree, similar with big-table). We 
> need to track per ledger which log files contribute entries to it, so that 
> in-memory index can be rebuilt from the tails of corresponding log files.
> 2. Use affinity concept to make ensembles of ledgers (belonging to same 
> topic) as identical as possible. This will help above 1. be more effective.
>  

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