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MapReduce, mail # user - Debug MR tasks impossible.


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Re: Debug MR tasks impossible.
Ravi Prakash 2012-03-29, 16:09
On 0.23 I usually breakpoint on DefaultContainerExecutor.java : 139. Modify
the script mentioned in nmPrivateContainerScriptPath to include JAVA remote
debugging options. Connect to the nodemanager and then breakpoint again in
MRAppMaster.java. Tedious. I know. :(

On Thu, Mar 29, 2012 at 11:06 AM, Ravi Prakash <[EMAIL PROTECTED]> wrote:

> Hi Pedro,
>
> I know its sub-optimal but you should be able to put in as many
> System.out.println / log messages as you want and you should be able to see
> them in stdout, and syslog files. Which version of hadoop are you using?
>
>
>
>
> On Thu, Mar 29, 2012 at 10:33 AM, Pedro Costa <[EMAIL PROTECTED]> wrote:
>
>> Hi,
>>
>> I'm trying to debug map and reduce tasks for a quite long time, and it
>> seems that it's impossible. MR are launched in new process and there's no
>> way to debug them. Even with IsolationRunner class it's impossible. This
>> isn't good because I really need to debug the class, to understand some
>> changes that I made to the code.
>>
>> I wonder how MapReduce programmers could debug the code that they
>> implemented?
>>
>> --
>> Best regards,
>>
>>
>