But would it be the case for multiple tasks running on the same worker and also both the tasks are running in client mode, so the one true is true for both or for neither. As mentioned earlier all the confs are same. I have checked and compared each conf.

As Abdeali mentioned it must be because the  way libraries are in both the environments. Also i verified by running the same script for jupyter environment and was able to get the same result using the normal script which i was running with spark-submit.

Currently i am searching for the ways the python packages are transferred from driver to spark cluster in client mode. Any info on that topic would be helpful.


On Wed, 11 Sep, 2019, 7:06 PM Patrick McCarthy, <pmccarthy@dstillery.com> wrote:
Are you running in cluster mode? A large virtualenv zip for the driver sent into the cluster on a slow pipe could account for much of that eight minutes.

On Wed, Sep 11, 2019 at 3:17 AM Dhrubajyoti Hati <dhruba.work@gmail.com> wrote:

I just ran the same script in a shell in jupyter notebook and find the performance to be similar. So I can confirm this is because the libraries used jupyter notebook python is different than the spark-submit python this is happening. 

But now I have a following question. Are the dependent libraries in a python script also transferred to the worker machines when executing a python script in spark. Because though the driver python versions are different, the workers machines will use their same python environment to run the code. If anyone can explain this part, it would be helpful.


Dhrubajyoti Hati.
Mob No: 9886428028/9652029028

On Wed, Sep 11, 2019 at 9:45 AM Dhrubajyoti Hati <dhruba.work@gmail.com> wrote:
Just checked from where the script is submitted i.e. wrt Driver, the python env are different. Jupyter one is running within a the virtual environment which is Python 2.7.5 and the spark-submit one uses 2.6.6. But the executors have the same python version right? I tried doing a spark-submit from jupyter shell, it fails to find python 2.7  which is not there hence throws error.

Here is the udf which might take time:
import base64
import zlib
def decompress(data):

bytecode = base64.b64decode(data)
d = zlib.decompressobj(32 + zlib.MAX_WBITS)
decompressed_data = d.decompress(bytecode )

Could this because of the two python environment mismatch from Driver side? But the processing
happens in the executor side?



On Wed, Sep 11, 2019 at 8:59 AM Abdeali Kothari <abdealikothari@gmail.com> wrote:
Maybe you can try running it in a python shell or jupyter-console/ipython instead of a spark-submit and check how much time it takes too.

Compare the env variables to check that no additional env configuration is present in either environment.

Also is the python environment for both the exact same? I ask because it looks like you're using a UDF and if the Jupyter python has (let's say) numpy compiled with blas it would be faster than a numpy without it. Etc. I.E. Some library you use may be using pure python and another may be using a faster C extension... 

What python libraries are you using in the UDFs? It you don't use UDFs at all and use some very simple pure spark functions does the time difference still exist? 

Also are you using dynamic allocation or some similar spark config which could vary performance between runs because the same resources we're not utilized on Jupyter / spark-submit? 

On Wed, Sep 11, 2019, 08:43 Stephen Boesch <javadba@gmail.com> wrote:
Sounds like you have done your homework to properly compare .   I'm guessing the answer to the following is yes .. but in any case:  are they both running against the same spark cluster with the same configuration parameters especially executor memory and number of workers?

Am Di., 10. Sept. 2019 um 20:05 Uhr schrieb Dhrubajyoti Hati <dhruba.work@gmail.com>:
No, i checked for that, hence written "brand new" jupyter notebook. Also the time taken by both are 30 mins and ~3hrs as i am reading a 500  gigs compressed base64 encoded text data from a hive table and decompressing and decoding in one of the udfs. Also the time compared is from Spark UI not  how long the job actually takes after submission. Its just the running time i am comparing/mentioning.

As mentioned earlier, all the spark conf params even match in two scripts and that's why i am puzzled what going on.

On Wed, 11 Sep, 2019, 12:44 AM Patrick McCarthy, <pmccarthy@dstillery.com> wrote:
It's not obvious from what you pasted, but perhaps the juypter notebook already is connected to a running spark context, while spark-submit needs to get a new spot in the (YARN?) queue.

I would check the cluster job IDs for both to ensure you're getting new cluster tasks for each.

On Tue, Sep 10, 2019 at 2:33 PM Dhrubajyoti Hati <dhruba.work@gmail.com> wrote:

I am facing a weird behaviour while running a python script. Here is what the code looks like mostly:

def fn1(ip):
   some code...

def fn2(row):
    some operations
    return row1

udf_fn1 = udf(fn1)
cdf = spark.read.table("xxxx") //hive table is of size > 500 Gigs with ~4500 partitions
ddf = cdf.withColumn("coly", udf_fn1(cdf.colz)) \
    .drop("colz") \
    .withColumnRenamed("colz", "coly")

edf = ddf \
    .filter(ddf.colp == 'some_value') \
    .rdd.map(lambda row: fn2(row)) \

print edf.count() // simple way for the performance test in both platforms

Now when I run the same code in a brand new jupyter notebook it runs 6x faster than when I run this python script using spark-submit. The configurations are printed and  compared from both the platforms and they are exact same. I even tried to run this script in a single cell of jupyter notebook and still have the same performance. I need to understand if I am missing something in the spark-submit which is causing the issue.  I tried to minimise the script to reproduce the same error without much code.

Both are run in client mode on a yarn based spark cluster. The machines from which both are executed are also the same and from same user.

What i found is the  the quantile values for median for one ran with jupyter was 1.3 mins and one ran with spark-submit was ~8.5 mins.  I am not able to figure out why this is happening.

Any one faced this kind of issue before or know how to resolve this?



Patrick McCarthy 

Senior Data Scientist, Machine Learning Engineering


470 Park Ave South, 17th Floor, NYC 10016


Patrick McCarthy 

Senior Data Scientist, Machine Learning Engineering


470 Park Ave South, 17th Floor, NYC 10016