Mark,
Great effort getting the original lucene index accessor package in this
shape. I am sure this will benefit a lot of people using Lucene in a
multithread env.
I have a quick question to ask you:
Do you have to use the core Lucene 2.3-dev in order to use the accessor?
I will take a look at your codes to see if I could help. I used a
slightly modified version of the original package in my project but it
breaks some of my tests. I hope your version works better.
Thanks a lot!
Jay
Mark Miller wrote:
I have sat down and rewrote IndexAccessor from scratch. I copied in the
same reference counting logic, pruned some things, and tried to make the
whole package a bit simpler to use. I have a few things to do, but its
pretty solid already. The only major thing I'd still like to do is add
an option to warm searchers before putting them in the Searcher cache.
Id like to writer some more tests as well. Any help greatly appreciated
if your interested in using the thing.
http://myhardshadow.com/indexaccessor/trunk/src/test/com/mhs/indexaccessor/SimpleSearchServer.java
Here is a an example of a class that can be instantiated in one of
multiple threads and read /modify a single index without worrying about
what any
of the other threads are doing to the index at any given time. This is a
very simple example of how to use the IndexAccessor and not necessarily an
example of best practices. The main idea is that you get your Writer,
Searcher, or Reader, and then be sure to release it as soon as your done
with it
in a finally block. For loading, you will want to load many docs with a
Writer (batch them) before releasing it, but remember that Readers will
not get a new view
of the index until you release all of the Writers. So beware hogging a
Writer unless you thats what your intending.
JavaDoc:
http://myhardshadow.com/indexaccessorapi/
Code:
http://myhardshadow.com/indexaccessor/trunk/
Jar:
http://myhardshadow.com/indexaccessorreleases/indexaccessor.jar
Your synchronized block concerns:
The synchronized blocks that control accesss to the IndexAccessor do not
have a huge impact on performance. Keep in mind that all of the work is
not done in a synchonrized block, just the retrieval of the Searcher,
Writer, Reader. Even if the synchronization makes the method twice as
expensive, it is still overpowered by the cost of parsing queries and
searching the index. This applies with or without contention. I wrote a
simple test and included the output below. You might use the IBM Lock
Analyzer for Java to further analyze these costs. Trust me, this thing
is speedy. Its many times better than using IndexModifier.
Without Contention
Just retrieve and release Searcher 100000 times
----
avg time:6.3E-4 ms
total time:63 ms
Parse query and search on 1 doc 100000 times
----
avg time:0.03107 ms
total time:3107 ms
With Contention (40 other threads running 80000 searches)
Just retrieve and release Searcher 100000 times
----
avg time:0.04643 ms
total time:4643 ms
Parse query and search on 1 doc 100000 times
----
avg time:0.64337 ms
total time:64337 ms
- Mark
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