Thanks for reacting Anshum,
I also posted this on the Compass forum, but I was not sure where the
responsibility was. But your information did give me a good start. From
the Compass' RAMDirectoryStore source code: "uses
org.apache.lucene.store.RAMDirectory"
So appearantly I use two separate Lucene RamDirectory instances, one for
each Compass/Lucene engine, which would mean that the data is garbage
collected. Good!
I also have the sheer impression that the id I postfix to the "ram://"
is quite useless. I cannot find any location where that information is
actually used to configure separate filesystems on a ram drive. As a
comparison, the FSDirectoryStore has a "configure" method which actually
uses the part behind the ://, but the RAMDirectoryStore only is created.
In fact the RAMDirectoryStore does nothing else aside from being
created; no deleteIndex is implemented, no cleanIndex, no nothing. It
seems a miracle it works at all ;-) The only thing that is present is a
delete-files loop in beforeCopyFrom.
So I think I dare to assume that the memory is garbage collected.
Thanks again.
Tom
Anshum wrote:
Hi Tom, perhaps this is regarding Compass and you would have wanted to post
this query there.
In case you are looking and asking about running 2 instances of lucene on
the machine with 2 separate indexes in RAM, could you specify :
* Do you use tmpfs or do you load it using the RamDirectory class?
* In case you use tmpfs, you'd have to clean it manually after releasing the
hold of the engine (by stopping or closing the old index reader). The
cleaning is done straight off by deleting the index or moving the index off
the tmpfs after closing the index reader. Incase you happen to do it without
closing the reader, though the dir won't be listed under the directory
listing but it would still be using all of that space (which you would only
realise if you run out of space i.e. have space constraints).
* In the other case, if you are just using the OS cache mechanism or
something like it, it would not get cleaned up but gradually be cleaned as
and when the OS needs to allocate more memory (that is how caching works).
--
Anshum
Naukri Labs!
On Tue, Jun 10, 2008 at 2:53 PM, Tom <[EMAIL PROTECTED]> wrote:
I have not been able to find much information about this, hence this
question.
Currently I use Lucene through Compass with the data stored in RAM. The
indexed information is updated daily and therefore I create a new
Compass/Lucene combination every day, let it load the new data and then swap
the active search engine (simply assigning a 'global' variable). So, all in
memory.
I'm not confident what this will do with the memory. In my setupo each
Compass/Lucene engine gets a separate ram store based on a different id per
engine:
...setSetting(CompassEnvironment.CONNECTION, "ram://" + id)
And this seems to be working okay. However:
1. Is this the correct way to have 2 engines running next to each other
(while the second one is loading the new data)?
2. After the engines are swapped, is the RAM store of the now not used
engine automatically cleaned up? If not, how do I?
Thanks for any help!
Tom
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