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From chen yong <cy...@hotmail.com>
Subject 答复: it does not stop at breakpoints which is in an anonymous function
Date Fri, 16 Sep 2016 14:18:44 GMT
Dear Dirceu,


I am totally confused . In your reply you mentioned ".....the count does that, ..." .However,
in the code snippet shown in  the attachment file FelixProblem.png of your previous mail,
 I cannot find any 'count' ACTION is called.  Would you please clearly show me the line it
is which triggeres the evaluation.

Thanks you very much
________________________________
发件人: Dirceu Semighini Filho <dirceu.semighini@gmail.com>
发送时间: 2016年9月16日 21:07
收件人: chen yong
抄送: user@spark.apache.org
主题: Re: 答复: 答复: 答复: 答复: t it does not stop at breakpoints which is in
an anonymous function

Hello Felix,
No, this line isn't the one that is triggering the execution of the function, the count does
that, unless your count val is a lazy val.
The count method is the one that retrieves the information of the rdd, it has do go through
all of it's data do determine how many records the RDD has.

Regards,

2016-09-15 22:23 GMT-03:00 chen yong <cy163@hotmail.com<mailto:cy163@hotmail.com>>:


Dear Dirceu,

Thanks for your kind help.
i cannot see any code line corresponding to "..... retrieve the data from your DataFrame/RDDs....".
which you suggested in the previous replies.

Later, I guess

the line

val test = count

is the key point. without it, it would not stop at the breakpont-1, right?



________________________________
发件人: Dirceu Semighini Filho <dirceu.semighini@gmail.com<mailto:dirceu.semighini@gmail.com>>
发送时间: 2016年9月16日 0:39
收件人: chen yong
抄送: user@spark.apache.org<mailto:user@spark.apache.org>
主题: Re: 答复: 答复: 答复: t it does not stop at breakpoints which is in an anonymous
function

Hi Felix,
Are sure your n is greater than 0?
Here it stops first at breakpoint 1, image attached.
Have you got the count to see if it's also greater than 0?

2016-09-15 11:41 GMT-03:00 chen yong <cy163@hotmail.com<mailto:cy163@hotmail.com>>:

Dear Dirceu


Thank you for your help.


Acutally, I use Intellij IDEA to dubug the spark code.


Let me use the following code snippet to illustrate my problem. In the code lines below, I've
set two breakpoints, breakpoint-1 and breakpoint-2. when i debuged the code, it did not stop
at breakpoint-1, it seems that the map

function was skipped and it directly reached and stoped at the breakpoint-2.

Additionally, I find the following two posts
(1)http://stackoverflow.com/questions/29208844/apache-spark-logging-within-scala
(2)https://www.mail-archive.com/user@spark.apache.org/msg29010.html

I am wondering whether loggin is an alternative approach to debugging spark anonymous functions.


val count = spark.parallelize(1 to n, slices).map { i =>
      val x = random * 2 - 1
      val y = random * 2 - 1 (breakpoint-1 set in this line)
      if (x*x + y*y < 1) 1 else 0
    }.reduce(_ + _)
val test = x (breakpoint-2 set in this line)



________________________________
发件人: Dirceu Semighini Filho <dirceu.semighini@gmail.com<mailto:dirceu.semighini@gmail.com>>
发送时间: 2016年9月14日 23:32
收件人: chen yong
主题: Re: 答复: 答复: t it does not stop at breakpoints which is in an anonymous function

I don't know which IDE do you use. I use Intellij, and here there is an Evaluate Expression
dialog where I can execute code, whenever it has stopped in a breakpoint.
In eclipse you have watch and inspect where you can do the same.
Probably you are not seeing the debug stop in your functions because you never retrieve the
data from your DataFrame/RDDs.
What are you doing with this function? Are you getting the result of this RDD/Dataframe at
some place?
You can add a count after the function that you want to debug, just for debug, but don't forget
to remove this after testing.



2016-09-14 12:20 GMT-03:00 chen yong <cy163@hotmail.com<mailto:cy163@hotmail.com>>:

Dear Dirceu,


thanks you again.


Actually,I never saw it stopped at the breakpoints no matter how long I wait.  It just skipped
the whole anonymous function to direactly reach the first breakpoint immediately after the
anonymous function body. Is that normal? I suspect sth wrong in my debugging operations or
settings. I am very new to spark and  scala.


Additionally, please give me some detailed instructions about  "....Some ides provide you
a place where you can execute the code to see it's results....". where is the PLACE


your help badly needed!


________________________________
发件人: Dirceu Semighini Filho <dirceu.semighini@gmail.com<mailto:dirceu.semighini@gmail.com>>
发送时间: 2016年9月14日 23:07
收件人: chen yong
主题: Re: 答复: t it does not stop at breakpoints which is in an anonymous function

You can call a count in the ide just to debug, or you can wait until it reaches the code,
so you can debug.
Some ides provide you a place where you can execute the code to see it's results.
Be aware of not adding this operations in your production code, because they can slow down
the execution of your code.



2016-09-14 11:43 GMT-03:00 chen yong <cy163@hotmail.com<mailto:cy163@hotmail.com>>:


Thanks for your reply.

you mean i have to insert some codes, such as xxxxx.count or xxxxx.collect, between the original
spark code lines to invoke some operations, right?
but, where is the right places to put my code lines?

Felix

________________________________
发件人: Dirceu Semighini Filho <dirceu.semighini@gmail.com<mailto:dirceu.semighini@gmail.com>>
发送时间: 2016年9月14日 22:33
收件人: chen yong
抄送: user@spark.apache.org<mailto:user@spark.apache.org>
主题: Re: t it does not stop at breakpoints which is in an anonymous function

Hello Felix,
Spark functions run lazy, and that's why it doesn't stop in those breakpoints.
They will be executed only when you call some methods of your dataframe/rdd, like the count,
collect, ...

Regards,
Dirceu

2016-09-14 11:26 GMT-03:00 chen yong <cy163@hotmail.com<mailto:cy163@hotmail.com>>:

Hi all,



I am newbie to spark. I am learning spark by debugging the spark code. It is strange to me
that it does not stop at breakpoints  which is in  an anonymous function, it is normal in
ordianry function, though. It that normal. How to obverse variables in  an anonymous function.


Please help me. Thanks in advance!


Felix





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