lucene-java-user mailing list archives

Site index · List index
Message view « Date » · « Thread »
Top « Date » · « Thread »
From Tincu Gabriel <tincu.gabr...@gmail.com>
Subject Re: search performance
Date Mon, 02 Jun 2014 12:09:09 GMT
MMapDirectory will do the job for you. RamDirectory has a big warning in
the class description stating that the performance will get killed by an
index larger than a few hundred MB, and NRTCachingDirectory is a wrapper
for RamDirectory and suitable for low update rates. MMap will use the
system RAM to cache as much of the index it can and only hit disk when the
portion of the index you're trying to access isn't cached. I'd put my money
on switching directory implementations and see what kind of performance
gains that brings to the table.


On Mon, Jun 2, 2014 at 11:50 AM, Jamie <jamie@mailarchiva.com> wrote:

> Jack
>
> First off, thanks for applying your mind to our performance problem.
>
>
> On 2014/06/02, 1:34 PM, Jack Krupansky wrote:
>
>> Do you have enough system memory to fit the entire index in OS system
>> memory so that the OS can fully cache it instead of thrashing with I/O? Do
>> you see a lot of I/O or are the queries compute-bound?
>>
> Nice idea. The index is 200GB, the machine currently has 128GB RAM. We are
> using SSDs, but disappointingly, installing them didn't reduce search times
> to acceptable levels. I'll have to check your last question regarding
> I/O... I assume it is I/O bound, though will double check...
>
> Currently, we are using
>
> fsDirectory = new NRTCachingDirectory(fsDir, 5.0, 60.0);
>
> Are you proposing we increase maxCachedMB or use the RAMDirectory? With
> the latter, we will still need to persistent the index data to disk, as it
> is undergoing constant updates.
>
>
>> You said you have a 128GB machine, so that sounds small for your index.
>> Have you tried a 256GB machine?
>>
> Nope..didn't think it would make much of a different. I suppose, assuming
> we could store the entire index in RAM it would be helpful. How does one do
> this with Lucene, while still persisting the data?
>
>
>> How frequent are your commits for updates while doing queries?
>>
> Around ten to fifteen documents are being constantly added per second.
>
> Thank again
>
>
> Jamie
>
>
> ---------------------------------------------------------------------
> To unsubscribe, e-mail: java-user-unsubscribe@lucene.apache.org
> For additional commands, e-mail: java-user-help@lucene.apache.org
>
>

Mime
  • Unnamed multipart/alternative (inline, None, 0 bytes)
View raw message