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From Eddie Epstein <eaepst...@gmail.com>
Subject Re: Synchonizing Batches AE and StatusCallbackListener
Date Fri, 21 Apr 2017 21:22:23 GMT
Hi Erik,

A few words about DUCC and your application. DUCC is a cluster controller
that includes a resource manager and 3 applications: batch processing, long
running services and singleton processes.

The batch processing application consists of a users CollectionReader which
defines work items and a users aggregate for processing work items that can
be replicated as desired across the cluster of machines. DUCC manages the
remote process scale out and distribution of work items. The aggregate can
be vertically scaled within each process so that in-heap data can be shared
by multiple instances of the aggregate. UIMA-AS is not required for this
simple threading model.

For most applications a work item is itself a collection, a CAS containing
references to the data to be processed, where the collection size is
designed to have small enough granularity to support scale out but big
enough granularity to avoid bottlenecks.

The users aggregate normally has an initial CasMultiplier that reads the
input data and creates the CASes to be fed to the rest of the pipeline.
When all children CASes are finished processing the work item CAS is routed
to the aggregate's CasConsumer to finalize the collection. DUCC considers
the work item complete only when the work item CAS is successfully
processed.

The system is quite robust to errors: uncaught exceptions, analytics
crashing, machines crashing, etc.

Regards,
Eddie


On Fri, Apr 21, 2017 at 2:12 PM, Olga Patterson <olga.patterson@utah.edu>
wrote:

> Erik,
>
> My team at the VA have developed an easy way of implementing UIMA AS
> pipelines and scaling them to a large number of nodes - using Leo framework
> that extends UIMA AS 2.8.1. We have run pipelines on over 200M documents
> scaled across multiple nodes with dozens of service instances and it
> performs great.
>
> Here is some info:
> http://department-of-veterans-affairs.github.io/Leo/
>
> The documentation for Leo reflects an earlier version of Leo, but if you
> are interested in using it with Java 8 and UIMA 2.8.1, we have not released
> the latest version in on the VA github yet but we can share it with you so
> that you can test it out and possibly provide your comments back to us.
>
> Leo has simple-to-use functionality for flexible batch read and write and
> it can work with any UIMA AEs and existing descriptor files and type system
> descriptions, so if you already have a pipeline, wrapping it with Leo would
> take just a few lines of code.
>
> Let me know if you are interested and I can help you to get started.
>
> Olga Patterson
>
>
>
>
>
>
>
> -----Original Message-----
> From: Jaroslaw Cwiklik <uimaee@gmail.com>
> Reply-To: "user@uima.apache.org" <user@uima.apache.org>
> Date: Friday, April 21, 2017 at 8:08 AM
> To: "user@uima.apache.org" <user@uima.apache.org>
> Subject: Re: Synchonizing Batches AE and StatusCallbackListener
>
>     Erik, thanks. This is more clear what you are trying to accomplish.
> First,
>     there are no plans to retire the CPE. It is supported and I don't know
> of
>     any plans to retire it. The only issue is ongoing development. My
> efforts
>     are focused on extending and improving UIMA-AS.
>
>     I don't have an answer yet how to handle the CPE crash scenario with
>     respect to batching and subsequent restart from the last known good
> batch.
>     Seems like some coordination would be needed to avoid redoing the whole
>     collection after a crash. Its been awhile since I've looked at the CPE.
>     Will take a look and see what is possible if anything.
>
>     There is another Apache UIMA project called DUCC which stands for
>     Distributed Uima Cluster Computing. From your email it looks like you
> have
>     a cluster of machines available. Here is a quick description of DUCC:
>
>     DUCC is a Linux cluster controller designed to scale out any UIMA
> pipeline
>     for high throughput collection processing jobs as well as for low
> latency
>     real-tme applications. Building on UIMA-AS, DUCC is particularly well
>     suited to run large memory Java analytics in multiple threads in order
> to
>     fully utilize multicore machines. DUCC manages the life cycle of all
>     processes deployed across the cluster, including non-UIMA processes
> such as
>     tomcat servers or VNC sessions.
>
>      You can find more info on this here:
>     https://uima.apache.org/doc-uimaducc-whatitam.html
>
>     In UIMA-AS batching is an application concern. I am a bit fuzzy on
>     implementation so perhaps someone else can comment how to implement
>     batching and how to handle errors. You can use a CasMultipler and a
> custom
>     FlowController to manage CASes and react to errors.The UIMA-AS service
> can
>     take an input CAS representing your batch, pass it on to the
> CasMultiplier,
>     generate CASes for each piece of work and deliver results to the
>     CasConsumer with a FlowController in the middle orchestrating the
> flow. I
>     defer to application deployment experts to provide you with more
> detail.
>
>     Jerry
>
>
>
>
>
>
>
>     On Fri, Apr 21, 2017 at 2:21 AM, Erik Fäßler <
> erik.faessler@uni-jena.de>
>     wrote:
>
>     > Hi Jerry,
>     >
>     > thanks a lot for your answer! I’m sorry that I didn’t make myself
> clearer.
>     > I will try again! :-)
>     > Here comes a lot of text, sorry for that. The post actually has two
> parts:
>     > The first explaining my issue, the second responding to the pointer
> to
>     > UIMA-AS.
>     >
>     > First: Yes, I use a CPE. I process text documents. Tens of millions
> of
>     > them.
>     > So, I have the following components to my issue, running with the
> CPE.
>     >
>     > 1. A CAS-Consumer (just an AnalysisEngine internally, of course).
> This
>     > consumer is responsible to serialise the document CAS into XMI and
> send the
>     > XMI to a database. It is a XMI-to-database consumer. For performance
>     > reasons, the XMI of multiple CASes is buffered and then sent as a
> batch,
>     > lets say, 50 CAS XMIs at a time.
>     > 2. A CPE StatusCallbackListener which also writes to the same
> database,
>     > but in another table. It logs into the database which documents have
> been
>     > successfully processed by the CPE. It also works on a batch basis.
>     >
>     > The goal: The CallbackListener should only mark those documents as
>     > successfully processed (i.e. as “finished”) where the CAS-Consumer
> actually
>     > has sent the XMI data to the database.
>     >
>     > Reason: I don’t want documents marked as “finished” where the XMI
> data is
>     > not in the database but still in the CAS buffer. Because when now the
>     > pipeline crashes, the XMI data never gets sent to the database.
> Then, the
>     > processing state is inconsistent: Documents that have not been
> written into
>     > the database are marked as successfully processed. But their data is
>     > missing.
>     >
>     > Also, not each XMI data is stored. There is a condition in the
> consumer to
>     > decide whether the XMI is to be stored or not. Thus, I cannot “create
>     > consistency” by checking which XMI made it into the database.
>     >
>     > Is this better understandable?
>     >
>     >
>     >
>     > Regarding UIMA-AS:
>     >
>     > I tried it out a few years back when it was rather new, UIMA 2.3.1 or
>     > something. Back then, it was like the following:
>     > 1. Install a broker (or something - ActiveMQ was it called?)
>     > 2. Configure it.
>     > 3. Start it.
>     > 4. For each AE you want to use, deploy the AE on some server in your
>     > cluster (multiple AEs can be bundled into an AAE).
>     > 5. Start a reader process that will then fill the broker queue.
>     > 6. Wait until processing is finished.
>     > 7. Stop all the AE services deployed to the cluster, if you want to
> save
>     > the resources.
>     > 8. Stop the broker.
>     >
>     > This was quite a while back so perhaps this is not exactly how it
> was. But
>     > it seemed overly complex to me. I had to login into each server
> where I
>     > wanted work to be done. We have like 20 nodes or something. Perhaps
> I could
>     > write a script for that, but then I would have to keep track of the
> servers
>     > that are free to use at a current time. Because I am not the only
> one using
>     > the cluster.
>     > And then I have to stop all AE “services”. Until then, they will use
>     > memory because they just idle when there is nothing more to do.
>     >
>     > In contrast, CPEs are self-contained projects in my case which I can
>     > distribute easily through our job system (SLURM).
>     >
>     > I thought all the setup for UIMA-AS would pay out in better
> performance.
>     > But in my - admittedly limited - tests there was not much of a
> performance
>     > difference. CPEs seemed to be a bit faster due to the lack of CAS
>     > serialization between reader and AEs.
>     >
>     > Of course, this was years in the past. Is the process a bit simpler
> today?
>     > Or perhaps I got it wrong to begin with, that’s possible. But I read
> the
>     > documentation back then and couldn’t see how to do things much
> simpler.
>     >
>     > BUT if CPEs can’t solve my issue and UIMA-AS can, then perhaps I
> will try
>     > it again.
>     >
>     > Another question: You said “CPE was replaced by UIMA-AS”. Does that
> mean
>     > that CPEs will eventually be removed from UIMA? Are they still a
> part of
>     > UIMA 3?
>     >
>     > Sorry for all the text!
>     >
>     > Best regards and thanks!
>     >
>     > Erik
>     >
>     > > On 20 Apr 2017, at 20:31, Jaroslaw Cwiklik <uimaee@gmail.com>
> wrote:
>     > >
>     > > Hi Erik, sorry for a delay responding to your question. This seems
> like a
>     > > CPE question is this right? I am not quite following what is the
> issue
>     > you
>     > > are running into. Could you explain this better? With a clearer
> problem
>     > > description perhaps others will jump in with an answer  :)
>     > >
>     > > Just FYI, the CPE was replaced by the UIMA-AS quite a long time
> ago.
>     > > Perhaps UIMA-AS can work better for you. You can read about it
> here:
>     > > https://uima.apache.org/d/uima-as-2.9.0/uima_async_scaleout.html
>     > >
>     > > Jerry
>     > > UIMA Team
>     > >
>     > > On Tue, Apr 18, 2017 at 5:56 AM, Erik Fäßler <
> erik.faessler@uni-jena.de>
>     > > wrote:
>     > >
>     > >> Hi all,
>     > >>
>     > >> I have a use case where a consumer of mine sends CAS XMI data
> into a
>     > >> database in batchProcessComplete(). I also use a
> StatusCallbackListener
>     > >> that logs into the database whether a document has been completed
>     > >> processing, this is also done batch wise.
>     > >> Now the issue is, if the pipeline crashes for any reason, I must
> start
>     > >> over because the “completion” flag from the CallbackListener and
> the
>     > data
>     > >> actually sent by the XMI consumer is not synchronised, i.e. I
> don’t
>     > know if
>     > >> the data has actually been sent for a document that has completed
>     > >> processing because everything is done batch-wise and not
> immediately for
>     > >> performance reasons. I also cannot just look into the database
> which XMI
>     > >> data is there because it only gets sent on a met condition.
>     > >>
>     > >> I would like to somehow communicate between the consumer and the
>     > >> CallbackListener to send their data for the same documents in
>     > agreement. Is
>     > >> there anything I can do to achieve this?
>     > >>
>     > >> Best,
>     > >>
>     > >> Erik
>     >
>     >
>
>
>

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