[ http://issues.apache.org/jira/browse/NUTCH-331?page=all ]
Sami Siren updated NUTCH-331:
-----------------------------
Fix Version/s: (was: 0.8)
> Fetcher incorrectly reports task progress to tasktracker resulting in skipped
> URLs
> ----------------------------------------------------------------------------------
>
> Key: NUTCH-331
> URL: http://issues.apache.org/jira/browse/NUTCH-331
> Project: Nutch
> Issue Type: Bug
> Components: fetcher
> Affects Versions: 0.8, 0.9
> Reporter: Andrzej Bialecki
> Priority: Critical
> Fix For: 0.9
>
>
> Each Fetcher task starts multiple FetcherThreads, which consume the input
> fetchlist. These threads may block for a long time after being started and
> after reading their input fetchlist entries, due to "politeness" settings.
> However, the map-reduce framework considers the task as complete when all
> input data is read.
> This causes the tasktracker to incorreclty assume that task processing is
> complete (because the task progress is 1.0, since all input has been
> consumed), whereas many URLs from the fetchlist may still be waiting for
> fetching, in blocked threads. The more threads is used the more apparent is
> this problem, because the final number of fetched pages may be short of the
> target number by as many as (numThreads * numMapTasks) entries.
> The final result of this is that only a part of the fetchlist is fetched,
> because Fetcher map tasks are stopped when their progress is 1.0.
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