[infinispan-dev] Feedback on Infinispan patch

[Sanne Grinovero]

Hi Łukasz,
you've rightful concerns, because the way the IndexWriter tries to
achieve the lock
that will bring some trouble; As far as I remember we decided in this
first release
to avoid multiple writer nodes because of this reasons
(that's written in your docs?)

Actually it shouldn't be very hard to do, as the LockStrategy is
pluggable (see changes from HSEARCH-345)
and you could implement one delegating to an Infinispan eager lock on some key,
like the default LockStrategy takes a file lock in the index directory.

Maybe it's simpler to support this distributed writing instead of
sending the queue to some single
(elected) node? Would be cool, as the Document Analysis effort would
be distributed,
but I have no idea if this would be more or less efficient than a
single node writing; it could
bring some huge data transfers along the wire during segments merging
(basically fetching
the whole index data at each node performing a segment merge); maybe
you'll need to
play with IndexWriter settings (
http://docs.jboss.org/hibernate/stable/search/reference/en/html_single/#lucene-indexing-performance
)
probably need to find the sweet spot for "merge_factor".
I just saw now that MergePolicy is now re-implementable, but I hope
that won't be needed.

Sanne

2009/9/21 Łukasz Moreń <lukasz.moren at gmail.com>:
> Hi,
>
> I'm wondering if it is reasonable to have multiple threads/nodes that
> modifies indexes in Lucene Directory based on Infinispan? Let's assume that
> two nodes try to update index in this same time. First one creates
> IndexWriter and obtains
> write lock. There is high propability that second node throws
> LockObtainFailedException (as one IndexWriter is allowed on single index)
> and index is not modified. How is that? Should be always only one node that
> makes changes in
> the index?
>
> Cheers,
> Lukasz
>
> W dniu 15 września 2009 01:39 użytkownik Łukasz Moreń
> <lukasz.moren at gmail.com> napisał:
>>
>> Hi,
>>
>> With using JMeter I wanted to check if Infinispan dir does not crash under
>> heavy load in "real" use and check performance in comparison with none/other
>> directories.
>> However appeared problem when multiple IndexWriters tries to modify index
>> (test InfinispanDirectoryTest) - random deadlocks, and Lucene exceptions.
>> IndexWriter tries to access files in index that were removed before. I'm
>> looking into it, but not having good idea.
>>
>> Concerning the last part, I think similar thing is done in
>> InfinispanDirectoryProviderTest. Many threads are making changes and
>> searching (not checking if db is in sync with index).
>> If threads finish their work, with Lucene query I'm checking if index
>> contains as many results as expected. Maybe you meant something else?
>> Would be good to run each node in different VM.
>>
>>> Great ! Looking forward to it. What state are things in at the moment
>>> if I want to play around with it ?
>>
>> Should work with with one master(updates index) and one many slave nodes
>> (sends changes to master). I tried with one master and one slave (both with
>> jms and jgroups backend) and worked ok. Still fails if multiple nodes want
>> to modify index.
>>
>> I've attached patch with current version.
>>
>> Cheers,
>> Łukasz
>>
>> 2009/9/13 Michael Neale <michael.neale at gmail.com>
>>>
>>> Great ! Looking forward to it. What state are things in at the moment
>>> if I want to play around with it ?
>>>
>>> Sent from my phone.
>>>
>>> On 13/09/2009, at 7:26 PM, Sanne Grinovero <sanne.grinovero at gmail.com>
>>> wrote:
>>>
>>> > 2009/9/12 Michael Neale <michael.neale at gmail.com>:
>>> >> That does sounds pretty cool. Would be nice if the lucene indexes
>>> >> could scale along with how people will want to use infinispan.
>>> >> Probably worth playing with.
>>> >
>>> > Sure, this is the goal of Łukasz's work; We know compass has
>>> > some good Directories, but we're building our own as one based
>>> > on Infinispan is not yet available.
>>> >
>>> >>
>>> >> Sent from my phone.
>>> >>
>>> >> On 13/09/2009, at 8:37 AM, Jeff Ramsdale <jeff.ramsdale at gmail.com>
>>> >> wrote:
>>> >>
>>> >>> I'm afraid I haven't followed the Infinispan-Lucene implementation
>>> >>> closely, but have you looked at the Compass Project?
>>> >>> (http://www.compass-project.org/overview.html) It provides a
>>> >>> simplified interface to Lucene (optional) as well as Directory
>>> >>> implementations built on Terracotta, Gigaspaces and Coherence. The
>>> >>> latter, in particular, might be a useful guide for the Infinispan
>>> >>> implementation. I believe it's mature enough to have solved many of
>>> >>> the most difficult problems of implementing Directory on a
>>> >>> distributed
>>> >>> Map.
>>> >>>
>>> >>> If someone has any experience with Compass (particularly it's
>>> >>> Directory implementations) I'd be interested in hearing about it...
>>> >>> It's Apache 2.0 licensed, btw.
>>> >>>
>>> >>> -jeff
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