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https://issues.apache.org/jira/browse/JENA-1552?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16497799#comment-16497799
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Andy Seaborne commented on JENA-1552:
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One side effect of the parallel loader is that it takes over the whole machine.
The loading process can make the machine unusable for interactive work, for
example: typing and mouse clicks get delayed for multiple seconds.
The phased loading algorithm provides a way to control the amount of resources
used at the same time.
> Bulk loader for TDB2 (phased loading)
> -------------------------------------
>
> Key: JENA-1552
> URL: https://issues.apache.org/jira/browse/JENA-1552
> Project: Apache Jena
> Issue Type: Improvement
> Components: TDB2
> Reporter: Andy Seaborne
> Assignee: Andy Seaborne
> Priority: Major
>
> Following on from JENA-1550, this ticket is for phased loading which combined
> features of the sequential loader and the parallel loader.
> When building all the persistent datastructures (parallel loader), the work
> on different indexes at the same time is competing for hardware resources,
> RAM and I/O bandwidth. As the size to load grows, this becomes a noticeable
> slowdown.
> The sequential loader is the other extreme of the design spectrum. It does
> work on one index at a time so as to maximize caching efficiency.
> Phased loading has parallel operation per phase and splits work into subsets
> of indexes.
> At 200m and loading to rotational disk, an experimental phased loader working
> with 2 indexes at a time, starts to become faster than parallel on the same
> hardware as used for the [figures in
> JENA-1550|https://issues.apache.org/jira/browse/JENA-1550#comment-16484269]
> (56K parallel, 76K phased).
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