yes, it is used in Nutch 1.x , but never used in Nutch 2.x. because in Nutch 2.x it will never generate selected url.
the correct expression of crawl.gen.crawl is milliseconds you can check the Nutch 1.x nutch-default.xml. the property description like this: <property> <name>crawl.gen.delay</name> <value>604800000</value> <description> This value, expressed in milliseconds, defines how long we should keep the lock on records in CrawlDb that were just selected for fetching. If these records are not updated in the meantime, the lock is canceled, i.e. they become eligible for selecting. Default value of this is 7 days (604800000 ms). </description> </property> Maybe it is wrong. On Fri, Aug 16, 2013 at 3:17 AM, kaveh minooie <[email protected]> wrote: > crawl.gen.delay -- Don't Grow Old, Grow Up... :-)

