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From Hussein Elgridly <huss...@broadinstitute.org>
Subject Re: Speeding up Aurora client job creation
Date Tue, 17 Mar 2015 19:18:54 GMT
For anyone following along at home, I managed to make my own THTTPClient
for thriftpy just fine. Unfortunately, thriftpy's TJSONProtocol seems to be
*a* JSON protocol, not *the* JSON protocol:

thrift: [1,"getJobSummary",1,0,{}]
thriftpy: {"metadata": {"ttype": 1, "name": "getJobSummary", "version": 1,
"seqid": 0}, "payload": {}}

Which is frustrating to say the least. I am now debating whether to:

1. Stub out the subset of the API that I actually need (currently only
createJob and getTasksWithoutConfigs);
2. Roll my own protocol, based on Thrift's code [1]; or
3. Backport my project to Python 2.7 and use official Thrift.

[1]
https://github.com/apache/thrift/blob/93fea15b51494a79992a5323c803325537134bd8/lib/py/src/protocol/TJSONProtocol.py


Hussein Elgridly
Senior Software Engineer, DSDE
The Broad Institute of MIT and Harvard


On 16 March 2015 at 23:37, Hussein Elgridly <hussein@broadinstitute.org>
wrote:

> As a general rule we're trying to stick to Python 3.4. I don't imagine
> implementing something a THTTPClient of my own will be too difficult,
> especially given that I have the Aurora client's TRequestsTransport [1] for
> reference.
>
> [1]
> https://github.com/apache/incubator-aurora/blob/master/src/main/python/apache/aurora/common/transport.py
>
> Hussein Elgridly
> Senior Software Engineer, DSDE
> The Broad Institute of MIT and Harvard
>
>
> On 16 March 2015 at 22:58, Bill Farner <wfarner@apache.org> wrote:
>
>> Exploring the possibilities - can you use python 2.7?  If so, you could
>> leverage some of the private libraries within the client and lower the
>> surface area of what you need to build.  It won't be a stable programmatic
>> API, but you might get moving faster.  I assume this is what Stephan is
>> suggesting.
>>
>> -=Bill
>>
>> On Mon, Mar 16, 2015 at 7:52 PM, Hussein Elgridly <
>> hussein@broadinstitute.org> wrote:
>>
>> > I'm not quite sure I understand your question, so I'll be painfully
>> > explicit instead.
>> >
>> > I don't want to use the existing Aurora client because it's slow
>> (Pystachio
>> > + repeated HTTP connection overheads, as detailed earlier in this
>> thread).
>> > Instead, I want to use the Thrift interface to talk to the Aurora
>> scheduler
>> > directly - I can skip Pystachio entirely and keep the HTTP connection
>> > open).
>> >
>> > I cannot use the official Thrift bindings for Python as they do not yet
>> > support Python 3 [1]. There is a third-party, pure Python
>> implementation of
>> > Thrift that does support Python 3 called thriftpy [2]. However, thriftpy
>> > does not include a THTTPClient transport, which is what the Aurora
>> > scheduler uses. I will therefore have to write my own THTTPClient
>> transport
>> > (and probably contribute it back to thriftpy).
>> >
>> > [1] https://issues.apache.org/jira/browse/THRIFT-1857
>> > [2] https://github.com/eleme/thriftpy
>> >
>> > Hussein Elgridly
>> > Senior Software Engineer, DSDE
>> > The Broad Institute of MIT and Harvard
>> >
>> >
>> > On 16 March 2015 at 19:11, Erb, Stephan <Stephan.Erb@blue-yonder.com>
>> > wrote:
>> >
>> > > Just to make sure I get this correctly: You say, you cannot use the
>> > > existing python client because it is python 2.7 only so you want to
>> > write a
>> > > new one in python 3?
>> > >
>> > > Regards,
>> > > Stephan
>> > > ________________________________________
>> > > From: Hussein Elgridly <hussein@broadinstitute.org>
>> > > Sent: Monday, March 16, 2015 11:44 PM
>> > > To: dev@aurora.incubator.apache.org
>> > > Subject: Re: Speeding up Aurora client job creation
>> > >
>> > > So this has now bubbled back to the top of my TODO list and I'm
>> actively
>> > > working on it. I am entirely new to Thrift so please forgive the
>> newbie
>> > > questions...
>> > >
>> > > I would like to talk to the Aurora scheduler directly from my (Python)
>> > > application using Thrift. Since I'm on Python 3.4 I've had to use
>> > thriftpy:
>> > > https://github.com/eleme/thriftpy
>> > >
>> > > As far as I can tell, the following should work (by default, thriftpy
>> > uses
>> > > a TBufferedTransport around a TSocket):
>> > >
>> > > ---
>> > > import thriftpy
>> > > import thriftpy.rpc
>> > >
>> > > aurora_api = thriftpy.load("api.thrift")
>> > >
>> > > client = thriftpy.rpc.make_client(aurora_api.AuroraSchedulerManager,
>> > > host="localhost", port=8081,
>> > > proto_factory=thriftpy.protocol.TJSONProtocolFactory() )
>> > >
>> > > print(client.getJobSummary())
>> > > ---
>> > >
>> > > Obviously I wouldn't be writing this email if it did work :) It hangs.
>> > >
>> > > I jumped into pdb and found it was sending the following payload:
>> > >
>> > > b'\x00\x00\x00\\{"metadata": {"name": "getJobSummary", "seqid": 0,
>> > "ttype":
>> > > 1, "version": 1}, "payload": {}}'
>> > >
>> > > to a socket that looked like this:
>> > >
>> > > <socket.socket fd=3, family=AddressFamily.AF_INET, type=2049, proto=0,
>> > > laddr=('<localhost's_private_ip>', 49167),
>> > raddr=('localhost's_private_ip',
>> > > 8081)>
>> > >
>> > > ...but was waiting forever to receive any data. Adding a timeout just
>> > > triggered the timeout.
>> > >
>> > > I'm stumped. Any clues?
>> > >
>> > >
>> > > Hussein Elgridly
>> > > Senior Software Engineer, DSDE
>> > > The Broad Institute of MIT and Harvard
>> > >
>> > >
>> > > On 12 February 2015 at 04:15, Erb, Stephan <
>> Stephan.Erb@blue-yonder.com>
>> > > wrote:
>> > >
>> > > > Hi Hussein,
>> > > >
>> > > > we also had slight performance problems when talking to Aurora. We
>> > ended
>> > > > up using the existing python client directly in our code (see
>> > > > apache.aurora.client.api.__init__.py). This allowed us to reuse the
>> api
>> > > > object and its scheduler connection, dropping a connection latency
>> of
>> > > about
>> > > > 0.3-0.4 seconds per request.
>> > > >
>> > > > Best Regards,
>> > > > Stephan
>> > > > ________________________________________
>> > > > From: Bill Farner <wfarner@apache.org>
>> > > > Sent: Wednesday, February 11, 2015 9:29 PM
>> > > > To: dev@aurora.incubator.apache.org
>> > > > Subject: Re: Speeding up Aurora client job creation
>> > > >
>> > > > To reduce that time you will indeed want to talk directly to the
>> > > > scheduler.  This will definitely require you to roll up your
>> sleeves a
>> > > bit
>> > > > and set up a thrift client to our api (based on api.thrift [1]),
>> since
>> > > you
>> > > > will need to specify your tasks in a format that the thermos
>> executor
>> > can
>> > > > understand.  Turns out this is JSON data, so it should not be *too*
>> > > > prohibitive.
>> > > >
>> > > > However, there is another technical limitation you will hit for the
>> > > > submission rate you are after.  The scheduler is backed by a durable
>> > > store
>> > > > whose write latency is at minimum the amount of time required to
>> fsync.
>> > > >
>> > > > [1]
>> > > >
>> > > >
>> > >
>> >
>> https://github.com/apache/incubator-aurora/blob/master/api/src/main/thrift/org/apache/aurora/gen/api.thrift
>> > > >
>> > > > -=Bill
>> > > >
>> > > > On Wed, Feb 11, 2015 at 11:46 AM, Hussein Elgridly <
>> > > > hussein@broadinstitute.org> wrote:
>> > > >
>> > > > > Hi folks,
>> > > > >
>> > > > > I'm looking at a use cases that involves submitting potentially
>> > > hundreds
>> > > > of
>> > > > > jobs a second to our Mesos cluster. My tests show that the aurora
>> > > client
>> > > > is
>> > > > > taking 1-2 seconds for each job submission, and that I can run
>> about
>> > > four
>> > > > > client processes in parallel before they peg the CPU at 100%.
I
>> need
>> > > more
>> > > > > throughput than this!
>> > > > >
>> > > > > Squashing jobs down to the Process or Task level doesn't really
>> make
>> > > > sense
>> > > > > for our use case. I'm aware that with some shenanigans I can
batch
>> > jobs
>> > > > > together using job instances, but that's a lot of work on my
>> current
>> > > > > timeframe (and of questionable utility given that the jobs
>> certainly
>> > > > won't
>> > > > > have identical resource requirements).
>> > > > >
>> > > > > What I really need is (at least) an order of magnitude speedup
in
>> > terms
>> > > > of
>> > > > > being able to submit jobs to the Aurora scheduler (via the client
>> or
>> > > > > otherwise).
>> > > > >
>> > > > > Conceptually it doesn't seem like adding a job to a queue should
>> be a
>> > > > thing
>> > > > > that takes a couple of seconds, so I'm baffled as to why it's
>> taking
>> > so
>> > > > > long. As an experiment, I wrapped the call to client.execute()
in
>> > > > > client.py:proxy_main in cProfile and called aurora job create
>> with a
>> > > very
>> > > > > simple test job.
>> > > > >
>> > > > > Results of the profile are in the Gist below:
>> > > > >
>> > > > > https://gist.github.com/helgridly/b37a0d27f04a37e72bb5
>> > > > >
>> > > > > Our of a 0.977s profile time, the two things that stick out to
me
>> > are:
>> > > > >
>> > > > > 1. 0.526s spent in Pystachio for a job that doesn't use any
>> templates
>> > > > > 2. 0.564s spent in create_job, presumably talking to the scheduler
>> > (and
>> > > > > setting up the machinery for doing so)
>> > > > >
>> > > > > I imagine I can sidestep #1 with a check for "{{" in the job
file
>> and
>> > > > > bypass Pystachio entirely. Can I also skip the Aurora client
>> entirely
>> > > and
>> > > > > talk directly to the scheduler? If so what does that entail,
and
>> are
>> > > > there
>> > > > > any risks associated?
>> > > > >
>> > > > > Thanks,
>> > > > > -Hussein
>> > > > >
>> > > > > Hussein Elgridly
>> > > > > Senior Software Engineer, DSDE
>> > > > > The Broad Institute of MIT and Harvard
>> > > > >
>> > > >
>> > >
>> >
>>
>
>

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