我已将nutch/solr 1.6配置为每12小时对包含约4000个文档和html页面的intranet进行爬网/索引。
如果我在一个空数据库中执行爬网程序，这个过程大约需要30分钟。当爬行执行了几天后，它会变得非常慢。查看日志文件，昨晚最后一步（SolrIndexer）似乎在1小时20分钟后开始，花了1个多小时。
因为索引的文档数量没有增长，我想知道为什么现在这么慢。
使用以下命令执行Nutch：
bin/nutch crawl -urlDir urls -solr http://localhost:8983/solr -dir nutchdb -depth 15 -topN 3000
nutch-site.xml包含：
<?xml version="1.0"?>
<?xml-stylesheet type="text/xsl" href="configuration.xsl"?>
<!-- Put site-specific property overrides in this file. -->
<configuration>
<property>
<name>http.agent.name</name>
<value>Internet Site Agent</value>
</property>
<property>
<name>plugin.includes</name>
<value>protocol-http|urlfilter-regex|parse-(tika|metatags)|index-(basic|anchor|metadata|more|http-header)|scoring-opic|urlnormalizer-(pass|regex|basic)</value>
</property>
<!-- Used only if plugin parse-metatags is enabled. -->
<property>
<name>metatags.names</name>
<value>description;keywords;published;modified</value>
<description> Names of the metatags to extract, separated by;.
Use '*' to extract all metatags. Prefixes the names with 'metatag.'
in the parse-metadata. For instance to index description and keywords,
you need to activate the plugin index-metadata and set the value of the
parameter 'index.parse.md' to 'metatag.description;metatag.keywords'.
</description>
</property>
<property>
<name>index.parse.md</name>
<value>metatag.description,metatag.keywords,metatag.published,metatag.modified</value>
<description> Comma-separated list of keys to be taken from the parse metadata to generate fields.
Can be used e.g. for 'description' or 'keywords' provided that these values are generated
by a parser (see parse-metatags plugin)
</description>
</property>
<property>
<name>db.ignore.external.links</name>
<value>true</value>
<description>Set this to false if you start crawling your website from
for example http://www.example.com but you would like to crawl
xyz.example.com. Set it to true otherwise if you want to exclude external links
</description>
</property>
<property>
<name>http.content.limit</name>
<value>10000000</value>
<description>The length limit for downloaded content using the http
protocol, in bytes. If this value is nonnegative (>=0), content longer
than it will be truncated; otherwise, no truncation at all. Do not
confuse this setting with the file.content.limit setting.
</description>
</property>
<property>
<name>fetcher.max.crawl.delay</name>
<value>1</value>
<description>
If the Crawl-Delay in robots.txt is set to greater than this value (in
seconds) then the fetcher will skip this page, generating an error report.
If set to -1 the fetcher will never skip such pages and will wait the
amount of time retrieved from robots.txt Crawl-Delay, however long that
might be.
</description>
</property>
<property>
<name>fetcher.threads.fetch</name>
<value>10</value>
<description>The number of FetcherThreads the fetcher should use.
This is also determines the maximum number of requests that are
made at once (each FetcherThread handles one connection). The total
number of threads running in distributed mode will be the number of
fetcher threads * number of nodes as fetcher has one map task per node.
</description>
</property>
<property>
<name>fetcher.threads.fetch</name>
<value>10</value>
<description>The number of FetcherThreads the fetcher should use.
This is also determines the maximum number of requests that are
made at once (each FetcherThread handles one connection). The total
number of threads running in distributed mode will be the number of
fetcher threads * number of nodes as fetcher has one map task per node.
</description>
</property>
<property>
<name>fetcher.server.delay</name>
<value>1.0</value>
<description>The number of seconds the fetcher will delay between
successive requests to the same server.</description>
</property>
<property>
<name>http.redirect.max</name>
<value>0</value>
<description>The maximum number of redirects the fetcher will follow when
trying to fetch a page. If set to negative or 0, fetcher won't immediately
follow redirected URLs, instead it will record them for later fetching.
</description>
</property>
<property>
<name>fetcher.threads.per.queue</name>
<value>2</value>
<description>This number is the maximum number of threads that
should be allowed to access a queue at one time. Replaces
deprecated parameter 'fetcher.threads.per.host'.
</description>
</property>
<property>
<name>link.delete.gone</name>
<value>true</value>
<description>Whether to delete gone pages from the web graph.</description>
</property>
<property>
<name>link.loops.depth</name>
<value>20</value>
<description>The depth for the loops algorithm.</description>
</property>
<!-- moreindexingfilter plugin properties -->
<property>
<name>moreIndexingFilter.indexMimeTypeParts</name>
<value>false</value>
<description>Determines whether the index-more plugin will split the mime-type
in sub parts, this requires the type field to be multi valued. Set to true for backward
compatibility. False will not split the mime-type.
</description>
</property>
<property>
<name>moreIndexingFilter.mapMimeTypes</name>
<value>false</value>
<description>Determines whether MIME-type mapping is enabled. It takes a
plain text file with mapped MIME-types. With it the user can map both
application/xhtml+xml and text/html to the same target MIME-type so it
can be treated equally in an index. See conf/contenttype-mapping.txt.
</description>
</property>
<!-- Fetch Schedule Configuration -->
<property>
<name>db.fetch.interval.default</name>
<!-- for now always re-fetch everything -->
<value>10</value>
<description>The default number of seconds between re-fetches of a page (less than 1 day).
</description>
</property>
<property>
<name>db.fetch.interval.max</name>
<!-- for now always re-fetch everything -->
<value>10</value>
<description>The maximum number of seconds between re-fetches of a page
(less than one day). After this period every page in the db will be re-tried, no
matter what is its status.
</description>
</property>
<!--property>
<name>db.fetch.schedule.class</name>
<value>org.apache.nutch.crawl.AdaptiveFetchSchedule</value>
<description>The implementation of fetch schedule. DefaultFetchSchedule simply
adds the original fetchInterval to the last fetch time, regardless of
page changes.</description>
</property>
<property>
<name>db.fetch.schedule.adaptive.inc_rate</name>
<value>0.4</value>
<description>If a page is unmodified, its fetchInterval will be
increased by this rate. This value should not
exceed 0.5, otherwise the algorithm becomes unstable.</description>
</property>
<property>
<name>db.fetch.schedule.adaptive.dec_rate</name>
<value>0.2</value>
<description>If a page is modified, its fetchInterval will be
decreased by this rate. This value should not
exceed 0.5, otherwise the algorithm becomes unstable.</description>
</property>
<property>
<name>db.fetch.schedule.adaptive.min_interval</name>
<value>60.0</value>
<description>Minimum fetchInterval, in seconds.</description>
</property>
<property>
<name>db.fetch.schedule.adaptive.max_interval</name>
<value>31536000.0</value>
<description>Maximum fetchInterval, in seconds (365 days).
NOTE: this is limited by db.fetch.interval.max. Pages with
fetchInterval larger than db.fetch.interval.max
will be fetched anyway.</description>
</property>
<property>
<name>db.fetch.schedule.adaptive.sync_delta</name>
<value>true</value>
<description>If true, try to synchronize with the time of page change.
by shifting the next fetchTime by a fraction (sync_rate) of the difference
between the last modification time, and the last fetch time.</description>
</property>
<property>
<name>db.fetch.schedule.adaptive.sync_delta_rate</name>
<value>0.3</value>
<description>See sync_delta for description. This value should not
exceed 0.5, otherwise the algorithm becomes unstable.</description>
</property>
<property>
<name>db.fetch.schedule.adaptive.sync_delta_rate</name>
<value>0.3</value>
<description>See sync_delta for description. This value should not
exceed 0.5, otherwise the algorithm becomes unstable.</description>
</property-->
<property>
<name>fetcher.threads.fetch</name>
<value>1</value>
<description>The number of FetcherThreads the fetcher should use.
This is also determines the maximum number of requests that are
made at once (each FetcherThread handles one connection). The total
number of threads running in distributed mode will be the number of
fetcher threads * number of nodes as fetcher has one map task per node.
</description>
</property>
<property>
<name>hadoop.tmp.dir</name>
<value>/opt/apache-nutch/tmp/</value>
</property>
<!-- Boilerpipe -->
<property>
<name>tika.boilerpipe</name>
<value>true</value>
</property>
<property>
<name>tika.boilerpipe.extractor</name>
<value>ArticleExtractor</value>
</property>
</configuration>
正如你所看到的，我已经将nutch配置为始终重新绘制所有文档。因为场地很小，现在应该可以重新蚀刻所有东西（第一次只需要30分钟…）。
我注意到，在crawldb/sgments文件夹中，每天都会创建大约40个新的分段。当然，数据库的磁盘大小增长非常快。
这是预期的行为吗？配置有问题吗？
有必要从nutchdb中删除早于db.default.fetch.interval的段。此间隔定义了何时应该重新蚀刻页面。
如果页面已被重新蚀刻，则可以删除旧的分段。
如果不删除段，步骤solrindexer必须读取太多段，并且速度非常慢（在我的情况下是一小时而不是4分钟）。