Hi:
I believe I figured out how the behavior here:
A file specified to SparkContext like this '/PATH/TO/SOME/FILE':
* Will be interpreted as 'HDFS://path/to/some/file', when settings for
HDFS are present in '/ETC/HADOOP/CONF/*-SITE.XML'.
* Will be interpreted as 'FILE:///path/to/some/file', (i.e. locally)
otherwise.
I confirmed this behavior by temporarily doing this:
* user$ sudo mv /etc/hadoop/conf /etc/hadoop/conf_
after which I re-ran my commands below. This time the SparkContext did,
indeed, look for and found, the file locally.
In summary, '/PATH/TO/SOME/FILE' is interpreted as an in-HDFS relative
path when a HDFS configuration is found; and interpreted as an absolute
local UNIX file path when a HDFS configuration is *not* found.
To be on the safe side, it's probably best to qualify local files with
'FILE:///' when that is what's intended; ahd with 'hdfs://' when HDFS is
what's intended.
Hopes this helps someone. :)
---
Sincerely,
Noel M. Vega
DiData
www.didata.us
On 2014-04-10 14:53, DiData wrote:
> Hi Alton:
>
> Thanks for the reply. I just wanted to build/use it from scratch to get a
> better intuition of what's a happening.
>
> Btw, using the binaries provided by Cloudera/CDH5 yielded the same issue as
> my compiled version (i.e. it, too,
> tried to access the HDFS / Name Node. Same exact error).
>
> However, a small breakthrough. Just now I tinkered some more and found that
> this variation works:
>
> REPLACE THIS: >>> distData =
> sc.textFile('/home/user/Download/ml-10M100K/ratings.dat') WITH THIS: >>>
> distData = sc.textFile('FILE:///
> [2]home/user/Download/ml-10M100K/ratings.dat') That is, use 'file:/// [2]'. I
> don't know if that is the correct way of specifying the URI for local files,
> or whether this just *happens to work*. The documents that I've read thus far
> haven't shown it that specified way, but I still have more to read.
>
> =:)
>
> Thank you,
>
> ~NMV
>
> On 04/10/2014 04:20 PM, Alton Alexander wrote:
>
> I am doing the exact same thing for the purpose of learning. I also
> don't have a hadoop cluster and plan to scale on ec2 as soon as I get
> it working locally.
>
> I am having good success just using the binaries on and not compiling
> from source... Is there a reason why you aren't just using the
> binaries?
>
> On Thu, Apr 10, 2014 at 1:30 PM, DiData <subscripti...@didata.us> wrote:
>
> Hello friends:
>
> I recently compiled and installed Spark v0.9 from the Apache distribution.
>
> Note: I have the Cloudera/CDH5 Spark RPMs co-installed as well (actually,
> the
> entire big-data suite from CDH is installed), but for the moment I'm using
> my
> manually built Apache Spark for 'ground-up' learning purposes.
>
> Now, prior to compilation (i.e. 'sbt/sbt clean compile') I specified the
> following:
>
> export SPARK_YARN=true
> export SPARK_HADOOP_VERSION=2.3.0-cdh5.0.0
>
> The resulting examples ran fine locally as well as on YARN.
>
> I'm not interested in YARN here; just mentioning it for completeness in case
> that matters in
> my upcoming question. Here is my issue / question:
>
> I start pyspark locally -- on one machine for API learning purposes -- as
> shown below, and attempt to
> interact with a local text file (not in HDFS). Unfortunately, the
> SparkContext (sc) tries to connect to
> a HDFS Name Node (which I don't currently have enabled because I don't need
> it).
>
> The SparkContext cleverly inspects the configurations in my
> '/etc/hadoop/conf/' directory to learn
> where my Name Node is, however I don't want it to do that in this case. I
> just want it to run a
> one-machine local version of 'pyspark'.
>
> Did I miss something in my invocation/use of 'pyspark' below? Do I need to
> add something else?
>
> (Btw: I searched but could not find any solutions, and the documentation,
> while good, doesn't
> quite get me there).
>
> See below, and thank you all in advance!
>
> user$ export PYSPARK_PYTHON=/usr/bin/bpython
> user$ export MASTER=local[8]
> user$ /home/user/APPS.d/SPARK.d/latest/bin/pyspark
> #
> ===========================================================================================
>>>> sc
> <pyspark.context.SparkContext object at 0x24f0f50>
>>>>
>>>> distData = sc.textFile('/home/user/Download/ml-10M100K/ratings.dat')
>>>> distData.count()
> [ ... snip ... ]
> Py4JJavaError: An error occurred while calling o21.collect.
> : java.net.ConnectException: Call From server01/192.168.0.15 to
> namenode:8020 failed on connection exception:
> java.net.ConnectException: Connection refused; For more details see:
> http://wiki.apache.org/hadoop/ConnectionRefused [1]
> [ ... snip ... ]
>>>>
>>>>
> #
> ===========================================================================================
>
> --
> Sincerely,
> DiData
--
Sincerely,
DiData
Links:
------
[1] http://wiki.apache.org/hadoop/ConnectionRefused
[2] file:///
