confusing debug message thrown by Configuration class

[Haijun Cao <Ha...@kindsight.net>]

Hi, 


I noticed that the org.apache.hadoop.conf.Configuration constructor will
log a message like below if DEBUG is enabled:

2008-05-19 15:59:43,237 DEBUG [main] conf.Configuration
java.io.IOException: config()
        at
org.apache.hadoop.conf.Configuration.<init>(Configuration.java:156)

The code is:

  public Configuration() {
    if (LOG.isDebugEnabled()) {
      LOG.debug(StringUtils.stringifyException(new
IOException("config()")));
    }


I am just wondering if anybody know why such messages are logged, as a
user, it made me think there is a "real" exception, but in fact, there
isn't.

BTW, I am using hadoop.fs package in a non-mapreduce java program.


Thanks.
Haijun

-----Original Message-----
From: Amar Kamat [mailto:amarrk@yahoo-inc.com] 
Sent: Monday, May 19, 2008 2:05 AM
To: core-user@hadoop.apache.org
Subject: Re: Master Failure

Fabrizio detto Mario wrote:
> How does Hadoop manage the failure of the JobTracker (Master Node)?
> For example, Google Map/Reduce version "aborts the MapReduce
computation if
> the master fails".
>
>   
Currently there is no recovery/backup strategy inplace to take care of 
this. We are currently working on it, look 
https://issues.apache.org/jira/browse/HADOOP-3245.
> As NameNode and SecondaryNameNode, exists a SecondaryJobTracker?
>   
No
Amar
> Thanks.
>
>   

Re: confusing debug message thrown by Configuration class

[Steve Loughran <st...@apache.org>]

Haijun Cao wrote:
> Hi, 
> 
> 
> I noticed that the org.apache.hadoop.conf.Configuration constructor will
> log a message like below if DEBUG is enabled:
> 
> 2008-05-19 15:59:43,237 DEBUG [main] conf.Configuration
> java.io.IOException: config()
>         at
> org.apache.hadoop.conf.Configuration.<init>(Configuration.java:156)
> 
> The code is:
> 
>   public Configuration() {
>     if (LOG.isDebugEnabled()) {
>       LOG.debug(StringUtils.stringifyException(new
> IOException("config()")));
>     }
> 
> 
> I am just wondering if anybody know why such messages are logged, as a
> user, it made me think there is a "real" exception, but in fact, there
> isn't.

I think they are there to let people see a stack trace of when a 
Configuration gets created; turn debug on and your log shows not just 
that things happen, but where they are.