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 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.
For a better control on the maximum simultaneous outgoing http
connections, as already done for any other http connections (crawls, rwi
search, p2p protocol) using the net.yacy.cora.protocol.http.HTTPClient
If not interested in displaying this on your search results and notably
on a peer with limited resources this can help saving some CPU and
outgoing network connections.
Consistently with the custom Solr http client used for https connections
to remote Solr peers or to YaCy external Solr storage.
This prevent remote Solr requests threads to wait for establishing a
connection to a remote peer longer than the configured timeout.
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.
* less CPU usage using the Solr 'allowedTime' parameter
* increase chances to get some results even when a first operation step
goes in time out by letting some time for final snippets results
processing
Solr can provide partial results for example when a processing time
limit (specified with the parameter `timeAllowed`) is exceeded.
Before this fix, getting partial results from an embedded Solr index
resulted in a ClassCastException :
"org.apache.solr.common.SolrDocumentList cannot be cast to
org.apache.solr.response.ResultContext".
That was caused by concurrent modifications (with addHighlightField()
function) to the same SolrQuery instance when requesting Solr on remote
peers in p2p search.
By not generating MD5 hashes on all words of indexed texts, processing
time is reduced by 30 to 50% on indexed documents with more than 1Mbytes
of plain text.
