SimpleDateFormat must not be used by concurrent threads without
synchronization for parsing or formating dates as it is not thread-safe
(internally holds a calendar instance that is not synchronized).
Prefer now DateTimeFormatter when possible as it is thread-safe without
concurrent access performance bottleneck (does not internally use
synchronization locks).
This organizes all urls to be loaded in separate queues for each host.
Each host separates the crawl depth into it's own queue. The primary
rule for urls taken from any queue is, that the crawl depth is minimal.
This produces a crawl depth which is identical to the clickdepth.
Furthermorem the crawl is able to create a much better balancing over
all hosts which is fair to all hosts that are in the queue.
This process will create a very large number of files for wide crawls in
the QUEUES folder: for each host a directory, for each crawl depth a
file inside the directory. A crawl with maxdepth = 4 will be able to
create 10.000s of files. To be able to use that many file readers, it
was necessary to implement a new index data structure which opens the
file only if an access is wanted (OnDemandOpenFileIndex). The usage of
such on-demand file reader shall prevent that the number of file
pointers is over the system limit, which is usually about 10.000 open
files. Some parts of YaCy had to be adopted to handle the crawl depth
number correctly. The logging and the IndexCreateQueues servlet had to
be adopted to show the crawl queues differently, because the host name
is attached to the port on the host to differentiate between http,
https, and ftp services.
are deleted to terminate the crawl because otherwise the crawl will go
on after the load-from-passive stack policy.
- better check if a crawl is terminated using the loader queue.
all unique links! This made it necessary, that a large portion of the
parser and link processing classes must be adopted to carry a different
type of link collection which carry a property attribute which are
attached to web anchors.
- introduction of a new URL class, AnchorURL
- the other url classes, DigestURI and MultiProtocolURI had been renamed
and refactored to fit into a new document package schema, document.id
- cleanup of net.yacy.cora.document package and refactoring
jdk-based logger tend to block
at java.util.logging.Logger.log(Logger.java:476) in concurrent
environments. This makes logging a main performance issue. To overcome
this problem, this is a add-on to jdk logging to put log entries on a
concurrent message queue and log the messages one by one using a
separate process.
- FTPClient uses the concurrent logging instead of the log4j logger
- time-out after 3 seconds to speed up display (may be incomplete)
- showing also all links from the balancer queue in the host list (after
the '/') and in the result browser view with tag 'loading'
- create a load list from the current list of known hosts
- do not create this list for each Balancer.pop access
- create the list from those hosts which have a zero-waiting time
- select 1/3 from that list which have the most urls waiting
- get hosts from the wainting list in random order
- fixes for some delta-time computations
- always load all urls from hosts which have never been loaded before
MultiProtocolURI during normalform computation because that should
always be done and also be done during initialization of the
MultiProtocolURI Object. The new normalform method takes only one
argument which should be 'true' unless you know exactly what you are
doing.
ready-prepared crawl list but at the stacks of the domains that are
stored for balanced crawling. This affects also the balancer since that
does not need to prepare the pre-selected crawl list for monitoring. As
a effect:
- it is no more possible to see the correct order of next to-be-crawled
links, since that depends on the actual state of the balancer stack the
next time another url is requested for loading
- the balancer works better since the next url can be selected according
to the current situation and not according to a pre-selected order.
Andreas