That's definitely surprising to me that you would be hitting a lot of GC
for this scenario. Are you setting --executor-cores and
--executor-memory? What are you setting them to?
-Sandy
On Thu, Feb 5, 2015 at 10:17 AM, Guillermo Ortiz <konstt2...@gmail.com>
wrote:
> Any idea why if I use more containers I get a lot of stopped because GC?
>
> 2015-02-05 8:59 GMT+01:00 Guillermo Ortiz <konstt2...@gmail.com>:
> > I'm not caching the data. with "each iteration I mean,, each 128mb
> > that a executor has to process.
> >
> > The code is pretty simple.
> >
> > final Conversor c = new Conversor(null, null, null,
> longFields,typeFields);
> > SparkConf conf = new SparkConf().setAppName("Simple Application");
> > JavaSparkContext sc = new JavaSparkContext(conf);
> > JavaRDD<byte[]> rdd = sc.binaryRecords(path, c.calculaLongBlock());
> >
> > JavaRDD<String> rddString = rdd.map(new Function<byte[], String>() {
> > @Override
> > public String call(byte[] arg0) throws Exception {
> > String result = c.parse(arg0).toString();
> > return result;
> > }
> > });
> > rddString.saveAsTextFile(url + "/output/" + System.currentTimeMillis()+
> "/");
> >
> > The parse function just takes an array of bytes and applies some
> > transformations like,,,
> > [0..3] an integer, [4...20] an String, [21..27] another String and so on.
> >
> > It's just a test code, I'd like to understand what it's happeing.
> >
> > 2015-02-04 18:57 GMT+01:00 Sandy Ryza <sandy.r...@cloudera.com>:
> >> Hi Guillermo,
> >>
> >> What exactly do you mean by "each iteration"? Are you caching data in
> >> memory?
> >>
> >> -Sandy
> >>
> >> On Wed, Feb 4, 2015 at 5:02 AM, Guillermo Ortiz <konstt2...@gmail.com>
> >> wrote:
> >>>
> >>> I execute a job in Spark where I'm processing a file of 80Gb in HDFS.
> >>> I have 5 slaves:
> >>> (32cores /256Gb / 7physical disks) x 5
> >>>
> >>> I have been trying many different configurations with YARN.
> >>> yarn.nodemanager.resource.memory-mb 196Gb
> >>> yarn.nodemanager.resource.cpu-vcores 24
> >>>
> >>> I have tried to execute the job with different number of executors a
> >>> memory (1-4g)
> >>> With 20 executors takes 25s each iteration (128mb) and it never has a
> >>> really long time waiting because GC.
> >>>
> >>> When I execute around 60 executors the process time it's about 45s and
> >>> some tasks take until one minute because GC.
> >>>
> >>> I have no idea why it's calling GC when I execute more executors
> >>> simultaneously.
> >>> The another question it's why it takes more time to execute each
> >>> block. My theory about the this it's because there're only 7 physical
> >>> disks and it's not the same 5 processes writing than 20.
> >>>
> >>> The code is pretty simple, it's just a map function which parse a line
> >>> and write the output in HDFS. There're a lot of substrings inside of
> >>> the function what it could cause GC.
> >>>
> >>> Any theory about?
> >>>
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> >>
>
