a main problem when crawling is long waiting time cuased by crawl-delay
values from robots.txt entries. that attribute is not supported by
google and interpreted by yandex and bing in different ways. In large
crawls there is always one host which blocks the whole crawl with
extreme large values. YaCy now still obeys crawl-delay but limits them
to 10 seconds.
Additionally the blocking logic when loading new robots.txt was analyzed
and a deadlock was removed. Furthermore the construction of new queue
lists was redesigned and it was ensured that always a large list of
different hosts for host-balancing is provided for the loader.
For finer control over which parsed documents can trigger an addition of
their links to the crawl stack, complementary to the existing crawl
depth parameter.
New "Media Type detection" section in the advanced crawl start page
allow to choose between :
- not loading URLs with unknown or unsupported file extension without
checking the actual Media Type (relying Content-Type header for now).
This was the old default behavior, faster, but not really accurate.
- always cross check URL file extension against the actual Media Type.
This lets properly parse URLs ending with an apparently odd file
extension, but which have actually a supported Media Type such as
text/html.
Sample URLs with misleading file extensions added as documentation in
the crawl start page.
fixes issue #244
When using the 'From Link-List of URL' as a crawl start, with lists in
the order of one or more thousands of links, the failreason_s Solr field
maximum size (32kb) was exceeded by the string representation of the URL
must-match filter when a crawl URL was rejected because not matching.
This makes possbile to set up much more advanced document crawl filters,
by filtering on one or more document indexed fields before inserting in
the index.
Initializing Thread names using the Thread constructor parameter is
faster as it already sets a thread name even if no customized one is
given, while an additional call to the Thread.setName() function
internally do synchronized access, eventually runs access check on the
security manager and performs a native call.
Profiling a running YaCy server revealed that the total processing time
spent on Thread.setName() for a typical p2p search was in the range of
seconds.
Required for proper operation when the default system locale is Turkish,
as dottless and dotted i characters have specific case conversion rules
in this language.
When a crawl is started, a new field to exclude content from scraping is
available. The field can be identified with the class name of div tags.
All text contained in such a div tag where the configured class name(s)
match are not indexed, while the remaining page is indexed.
Using a Reentrant lock instead of the intrinsic synchronization lock
permits limiting the blocking time to acquire a lock.
Useful on a very busy Cache concurrently accessed by many threads : when
the time to acquire a lock is too high, getting/storing content on the
cache becomes inefficient, and it is then better to fall back to loading
remote resources.
Illustrated by the CacheTest stress test and some traces reported in
mantis 751 ( http://mantis.tokeek.de/view.php?id=751 )
Shutdown was hanging in CrawlQueues.close() at
this.workerQueue.put(POISON_REQUEST) when config value
crawler.MaxActiveThreads was greater than 200.
Revealed by "Collision" Threads dumps in mantis 689
(http://mantis.tokeek.de/view.php?id=689#c1312)
Fixed consistency between this.worker.length and this.workerQueue
capacity, and made the process more reliable using non-blocking offer()
function.
Even after network switch, ErroCache was still holding a reference to
the previous Solr cores, thus becoming useless until next YaCy restart.
Initial error cache filling with recent errors from the index was also
missing after the swtich.
If remote crawl option is not activated, skip init of remoteCrawlJob to save the resources of queue and ideling thread.
Deploy of the remoteCrawlJob deferred on activation of the option.
Michael Peter Christen