Hi,
I think I've found the main problem with massive parallel ingestion.
I'm working with the last github snapshot.
In org.fcrepo.server.storage.DefaultDOManager, the getIngestWriter method
should not be synchronized as it seems there is only a single instance of that
class for the server. The internal objects of this class seem to be correctly
synchronized (pid generation) of new objects are recreated on each call (inside
Translator, a new DODeserializer is created and the same happens inside the
Validator).
I've tested with FOXML ingestion and now almost all the CPUs are used. I've not
been deeper to check that every inserted object is not corrupted, but after a
quick look, it seems OK. I guess the same kind of patch could also apply on
object deletion.
If one of you that better understand that part could have a look, it seems it
would be a nice patch, not too hard to test, with great performance
improvements.
Regards,
Nicolas HERVE
On 28/09/2012 11:25, Nicolas Hervé wrote:
Hi,
indeed, it seems we are exactly in the same configuration (millions of DO with
some metadata and external content) with almost the same hardware. I've not
identified the bottleneck in the massive parallel ingestion process right now,
but I highly suspect a synchronized portion of code somewhere in the chain. I
hope Edwin could say more about this :-)
For the querying of dc fields, index have to be created in the Mysql schema and
SQL queries are far from being optimal. Currently I only patched for my own
purposes (my datamodel / my queries) and I bypass some code portions in the
following classes :
org.fcrepo.server.search.FieldSearchSQLImpl
org.fcrepo.server.search.FieldSearchResultSQLImpl
I'm really new to Fedora Commons but, from what I understand, these SQL part is
quite old. Changing them for optimizations purposes could imply behaviour
changes for other people. That's why I don't think simple patches could do the
job. It would need a complete refactoring. That could only be done with a
global point of view on the different way this classes are used in the
different contexts where Fedora instances are running.
Feel free to contact me to discuss this more precisely.
Regards,
Nicolas HERVE
+33 1 49 83 21 66 (GMT + 2)
On 27/09/2012 18:23, Jason V wrote:
Hi Nicolas,
My name is Jason Varghese and I'm a senior developer at the New York Public
Library. I think you are doing work similar to what I am presently doing based
on reading some of your posts.
We have a relatively large scale Fedora implementation here. We've had all the
hardware in place for some time and are in the process of migrating from a
large homegrown repository to a Fedora based platform. We have a single Fedora
ingest machine and 3 Fedora readers. The ingest machine alone is 4 x 6 core
processors w/ 128GB RAM. I'm in the process of generating about 1 million+
digital objects and attaching to each DO all the metadata (as managed content
datastreams) and all the digital assets (as external content datastreams). The
digital assets currently are about 183 TB of content (this is replicated at two
sites). I have a multithreaded java client I wrote to accomplish the task for
the Fedora ingest/DO generation and I use the Mediashelf REST API client for
connectivity to Fedora. I was able to successfully ingest 10's of thousands of
digital objects, but really need ensure this process performs optimally and
scales for millions of objects. What bottlenecks were you able to identify when
running your multithreaded ingest process? Look forward to learning/sharing
experiences from this process with you and the community and possibly
collaborating. Thanks
Jason Varghese
NYPL
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