nutch -crawldelay-fetcher.server.delay的控制因素

1 除了配置文件中 fetcher.server.delay
<property>
  <name>fetcher.server.delay</name>
  <value>0.0</value>
  <description>The number of seconds the fetcher will delay between 
   successive requests to the same server.</description>
</property>

2 来自机器人协议的约束

　　　　　　　　　　 FetchItemQueue fiq = fetchQueues.getFetchItemQueue(fit.queueID);
                  fiq.crawlDelay = rules.getCrawlDelay();
                  if (LOG.isDebugEnabled()) {
                    LOG.info("Crawl delay for queue: " + fit.queueID + " is set to " + fiq.crawlDelay + " as per robots.txt. url: " + fit.url);
                  }