Ruslan Sivak wrote:
Michael McCandless wrote:
Ruslan Sivak wrote:
Michael McCandless wrote:
Ruslan Sivak wrote:
Since my app would be multithreaded, there could be multiple
threads accessing the reader, while i'm reloading it. This
means that if I close the reader, and another thread is using
it, it might get an exception.
The normal approach here is open a new reader, start sending new
searches to the new reader, and only once all existing searches
(and, possibly, search sessions, if for example you want
paginating through results to not suddenly change on the user)
are done with the old reader do you close the old one.
How exactly would I do something like this? I'm not sure where
to start. From what I understand, the reader will be auto closed
when there are no more references to it. What if I did somehting
like this
Private IndexReader reader;
public IndexReader getReader()
{
if (we are reloading)
{
Directory dir = new RAMDirectory (indexName);
reader = IndexReader.open(dir);
}
return reader;
}
public Results search(String searchTerms)
{
IndexReader r=getReader()
//Do search and return results
}
This should work, right? The local variable will hold a
reference to a reader that it's using, and once it goes out of
use, it should auto close, correct? Is closing the reader even
necessary? Won't it just get collected by the GC once there are
no more references to it?
Well you could keep a counter of how many searches are presently
using the previous reader, and then the final search to finish
with the previous reader would close it?
GC doesn't actually "close" the reader, though since you're using
RAMDirectory, you're not actually consuming any file descriptors
so I think it might be OK for you to never close and simply
replace your reader with the newly reopened one? Normally this is
not recommended, ie, a reader against an FSDirectory uses up
precious file descriptors...
Mike
What about using something like decref? Does anyone know the
proper way to use it? From the docs:
decRef
protected void *decRef*()
throws IOException <http://java.sun.com/j2se/1.4/docs/
api/java/io/IOException.html>
Decreases the refCount of this IndexReader instance. If the
refCount drops to 0, then pending changes are committed to the
index and this reader is closed.
That's a very good question!
Well ... that's a protected method. I think it would in fact work,
except, it would only handle closing the reader (not the searcher).
Though, IndexSearcher.close() currently does nothing besides closing
the reader; but in theory that may change some day.
You can do the same thing (reference counting) above your searcher and
that would work.
Mike
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