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From Davies Liu <davies....@gmail.com>
Subject Re: Mesos Spark Fine Grained Execution - CPU count
Date Sun, 25 Dec 2016 06:14:53 GMT
Using 0 for spark.mesos.mesosExecutor.cores is better than dynamic
allocation, but have to pay a little more overhead for launching a
task, which should be OK if the task is not trivial.

Since the direct result (up to 1M by default) will also go through
mesos, it's better to tune it lower, otherwise mesos could become the
bottleneck.

spark.task.maxDirectResultSize

On Mon, Dec 19, 2016 at 3:23 PM, Chawla,Sumit <sumitkchawla@gmail.com> wrote:
> Tim,
>
> We will try to run the application in coarse grain mode, and share the
> findings with you.
>
> Regards
> Sumit Chawla
>
>
> On Mon, Dec 19, 2016 at 3:11 PM, Timothy Chen <tnachen@gmail.com> wrote:
>
>> Dynamic allocation works with Coarse grain mode only, we wasn't aware
>> a need for Fine grain mode after we enabled dynamic allocation support
>> on the coarse grain mode.
>>
>> What's the reason you're running fine grain mode instead of coarse
>> grain + dynamic allocation?
>>
>> Tim
>>
>> On Mon, Dec 19, 2016 at 2:45 PM, Mehdi Meziane
>> <mehdi.meziane@ldmobile.net> wrote:
>> > We will be interested by the results if you give a try to Dynamic
>> allocation
>> > with mesos !
>> >
>> >
>> > ----- Mail Original -----
>> > De: "Michael Gummelt" <mgummelt@mesosphere.io>
>> > À: "Sumit Chawla" <sumitkchawla@gmail.com>
>> > Cc: user@mesos.apache.org, dev@mesos.apache.org, "User"
>> > <user@spark.apache.org>, dev@spark.apache.org
>> > Envoyé: Lundi 19 Décembre 2016 22h42:55 GMT +01:00 Amsterdam / Berlin /
>> > Berne / Rome / Stockholm / Vienne
>> > Objet: Re: Mesos Spark Fine Grained Execution - CPU count
>> >
>> >
>> >> Is this problem of idle executors sticking around solved in Dynamic
>> >> Resource Allocation?  Is there some timeout after which Idle executors
>> can
>> >> just shutdown and cleanup its resources.
>> >
>> > Yes, that's exactly what dynamic allocation does.  But again I have no
>> idea
>> > what the state of dynamic allocation + mesos is.
>> >
>> > On Mon, Dec 19, 2016 at 1:32 PM, Chawla,Sumit <sumitkchawla@gmail.com>
>> > wrote:
>> >>
>> >> Great.  Makes much better sense now.  What will be reason to have
>> >> spark.mesos.mesosExecutor.cores more than 1, as this number doesn't
>> include
>> >> the number of cores for tasks.
>> >>
>> >> So in my case it seems like 30 CPUs are allocated to executors.  And
>> there
>> >> are 48 tasks so 48 + 30 =  78 CPUs.  And i am noticing this gap of 30 is
>> >> maintained till the last task exits.  This explains the gap.   Thanks
>> >> everyone.  I am still not sure how this number 30 is calculated.  ( Is
>> it
>> >> dynamic based on current resources, or is it some configuration.  I
>> have 32
>> >> nodes in my cluster).
>> >>
>> >> Is this problem of idle executors sticking around solved in Dynamic
>> >> Resource Allocation?  Is there some timeout after which Idle executors
>> can
>> >> just shutdown and cleanup its resources.
>> >>
>> >>
>> >> Regards
>> >> Sumit Chawla
>> >>
>> >>
>> >> On Mon, Dec 19, 2016 at 12:45 PM, Michael Gummelt <
>> mgummelt@mesosphere.io>
>> >> wrote:
>> >>>
>> >>> >  I should preassume that No of executors should be less than number
>> of
>> >>> > tasks.
>> >>>
>> >>> No.  Each executor runs 0 or more tasks.
>> >>>
>> >>> Each executor consumes 1 CPU, and each task running on that executor
>> >>> consumes another CPU.  You can customize this via
>> >>> spark.mesos.mesosExecutor.cores
>> >>> (https://github.com/apache/spark/blob/v1.6.3/docs/running-on-mesos.md)
>> and
>> >>> spark.task.cpus
>> >>> (https://github.com/apache/spark/blob/v1.6.3/docs/configuration.md)
>> >>>
>> >>> On Mon, Dec 19, 2016 at 12:09 PM, Chawla,Sumit <sumitkchawla@gmail.com
>> >
>> >>> wrote:
>> >>>>
>> >>>> Ah thanks. looks like i skipped reading this "Neither will executors
>> >>>> terminate when they’re idle."
>> >>>>
>> >>>> So in my job scenario,  I should preassume that No of executors
should
>> >>>> be less than number of tasks. Ideally one executor should execute
1
>> or more
>> >>>> tasks.  But i am observing something strange instead.  I start my
job
>> with
>> >>>> 48 partitions for a spark job. In mesos ui i see that number of
tasks
>> is 48,
>> >>>> but no. of CPUs is 78 which is way more than 48.  Here i am assuming
>> that 1
>> >>>> CPU is 1 executor.   I am not specifying any configuration to set
>> number of
>> >>>> cores per executor.
>> >>>>
>> >>>> Regards
>> >>>> Sumit Chawla
>> >>>>
>> >>>>
>> >>>> On Mon, Dec 19, 2016 at 11:35 AM, Joris Van Remoortere
>> >>>> <joris@mesosphere.io> wrote:
>> >>>>>
>> >>>>> That makes sense. From the documentation it looks like the executors
>> >>>>> are not supposed to terminate:
>> >>>>>
>> >>>>> http://spark.apache.org/docs/latest/running-on-mesos.html#
>> fine-grained-deprecated
>> >>>>>>
>> >>>>>> Note that while Spark tasks in fine-grained will relinquish
cores as
>> >>>>>> they terminate, they will not relinquish memory, as the
JVM does
>> not give
>> >>>>>> memory back to the Operating System. Neither will executors
>> terminate when
>> >>>>>> they’re idle.
>> >>>>>
>> >>>>>
>> >>>>> I suppose your task to executor CPU ratio is low enough that
it looks
>> >>>>> like most of the resources are not being reclaimed. If your
tasks
>> were using
>> >>>>> significantly more CPU the amortized cost of the idle executors
>> would not be
>> >>>>> such a big deal.
>> >>>>>
>> >>>>>
>> >>>>> —
>> >>>>> Joris Van Remoortere
>> >>>>> Mesosphere
>> >>>>>
>> >>>>> On Mon, Dec 19, 2016 at 11:26 AM, Timothy Chen <tnachen@gmail.com>
>> >>>>> wrote:
>> >>>>>>
>> >>>>>> Hi Chawla,
>> >>>>>>
>> >>>>>> One possible reason is that Mesos fine grain mode also takes
up
>> cores
>> >>>>>> to run the executor per host, so if you have 20 agents running
Fine
>> >>>>>> grained executor it will take up 20 cores while it's still
running.
>> >>>>>>
>> >>>>>> Tim
>> >>>>>>
>> >>>>>> On Fri, Dec 16, 2016 at 8:41 AM, Chawla,Sumit <
>> sumitkchawla@gmail.com>
>> >>>>>> wrote:
>> >>>>>> > Hi
>> >>>>>> >
>> >>>>>> > I am using Spark 1.6. I have one query about Fine Grained
model in
>> >>>>>> > Spark.
>> >>>>>> > I have a simple Spark application which transforms
A -> B.  Its a
>> >>>>>> > single
>> >>>>>> > stage application.  To begin the program, It starts
with 48
>> >>>>>> > partitions.
>> >>>>>> > When the program starts running, in mesos UI it shows
48 tasks and
>> >>>>>> > 48 CPUs
>> >>>>>> > allocated to job.  Now as the tasks get done, the number
of active
>> >>>>>> > tasks
>> >>>>>> > number starts decreasing.  How ever, the number of
CPUs does not
>> >>>>>> > decrease
>> >>>>>> > propotionally.  When the job was about to finish, there
was a
>> single
>> >>>>>> > remaininig task, however CPU count was still 20.
>> >>>>>> >
>> >>>>>> > My questions, is why there is no one to one mapping
between tasks
>> >>>>>> > and cpus
>> >>>>>> > in Fine grained?  How can these CPUs be released when
the job is
>> >>>>>> > done, so
>> >>>>>> > that other jobs can start.
>> >>>>>> >
>> >>>>>> >
>> >>>>>> > Regards
>> >>>>>> > Sumit Chawla
>> >>>>>
>> >>>>>
>> >>>>
>> >>>
>> >>>
>> >>>
>> >>> --
>> >>> Michael Gummelt
>> >>> Software Engineer
>> >>> Mesosphere
>> >>
>> >>
>> >
>> >
>> >
>> > --
>> > Michael Gummelt
>> > Software Engineer
>> > Mesosphere
>>



-- 
 - Davies

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