spark-user mailing list archives

Site index · List index
Message view « Date » · « Thread »
Top « Date » · « Thread »
From Andrew Ash <and...@andrewash.com>
Subject Re: Why does sortByKey launch cluster job?
Date Wed, 08 Jan 2014 04:47:56 GMT
Hi Josh,

I just ran into this again myself and noticed that the source hasn't
changed since we discussed in December.  Should I file an official bug in
Jira?

Andrew


On Tue, Dec 10, 2013 at 8:34 AM, Josh Rosen <rosenville@gmail.com> wrote:

> I wonder whether making RangePartitoner .rangeBounds into a lazy val would
> fix this (
> https://github.com/apache/incubator-spark/blob/6169fe14a140146602fb07cfcd13eee6efad98f9/core/src/main/scala/org/apache/spark/Partitioner.scala#L95).
>  We'd need to make sure that rangeBounds() is never called before an action
> is performed.  This could be tricky because it's called in the
> RangePartitioner.equals() method.  Maybe it's sufficient to just compare
> the number of partitions, the ids of the RDDs used to create the
> RangePartitioner, and the sort ordering.  This still supports the case
> where I range-partition one RDD and pass the same partitioner to a
> different RDD.  It breaks support for the case where two range partitioners
> created on different RDDs happened to have the same rangeBounds(), but it
> seems unlikely that this would really harm performance since it's probably
> unlikely that the range partitioners are equal by chance.
>
>
> On Tue, Dec 10, 2013 at 8:18 AM, Ryan Prenger <ryan@tracevector.com>wrote:
>
>> Thanks for the responses!  I agree that b seems like it would be better.
>>  I could imagine optimizations that could be made if a filter call came
>> after the sortByKey that would make the initial partitioning sub-optimal.
>>  Plus this way, it's a pain to use in the REPL.
>>
>> Cheers,
>>
>> Ryan
>>
>>
>> On Tue, Dec 10, 2013 at 7:06 AM, Andrew Ash <andrew@andrewash.com> wrote:
>>
>>> Since sortByKey() invokes those right now, we should either a) change
>>> the documentation to treat note that it kicks off actions or b) change the
>>> method to execute those things lazily.
>>>
>>> Personally I'd prefer b but don't know how difficult that would be.
>>>
>>>
>>> On Tue, Dec 10, 2013 at 1:52 AM, Jason Lenderman <jslenderman@gmail.com>wrote:
>>>
>>>> Hey Ryan,
>>>>
>>>> The *sortByKey* method creates a *RangePartitioner* (see
>>>> Partitioner.scala), and the initialization code of the
>>>> *RangePartitioner* invokes actions *count* and *sample*.
>>>>
>>>>
>>>> Jason
>>>>
>>>>
>>>>
>>>>
>>>> On Mon, Dec 9, 2013 at 7:01 PM, Ryan Prenger <ryan@tracevector.com>wrote:
>>>>
>>>>> sortByKey is listed as a data transformation, not an action, yet it
>>>>> launches a job.  This doesn't seem to square with the documentation.
>>>>>
>>>>> Ryan
>>>>>
>>>>
>>>>
>>>
>>
>

Mime
View raw message