[jira] [Commented] (PIRK-65) Debug Logging Not Working within Distributed Applications

["Walter Ray-Dulany (JIRA)" <ji...@apache.org>]

    [ https://issues.apache.org/jira/browse/PIRK-65?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15514313#comment-15514313 ] 

Walter Ray-Dulany commented on PIRK-65:
---------------------------------------

I've been digging around on this. 

First I thought that perhaps we weren't setting the right property file variables to ensure the log level we wanted. I did a bunch of things, but began to suspect this wasn't the problem when, after eliminating the entire contents of log4j2.xml, the distributed tests produced exactly the same logs as before.

Then I thought the problem was some incompatibility between hadoop (which only knows log4j1) and use (using log4j2), and so I rolled my local branch back to log4j1, and tried a bunch of different options suggested by various internet search hits in a log4j.properties file. This, frustratingly, also did nothing.

Finally, I found some posts that explained things. [this post|http://stackoverflow.com/a/29117078] describes how the log4j levels are determined in a hadoop/yarn system: for the driver, by a system-wide log4j.properties file, and for yarn, by either a data node-by-data node config file container-log4j.properties or, if that doesn't exist, by the values hard-coded into the hadoop-yarn-server-nodemanager jar file. The author of that post assures the reader that we cannot change these no matter how many log4j.properties files we add because the classpath used by hadoop will pre-empt them. I did some reading to know why/how hadoop was influencing the classpath: I found [this explanation|http://stackoverflow.com/a/28260868] sufficiently illuminating, and essentially confirmed what the first-linked post above was saying.

I haven't yet tested this in a system where I was anything but a tenant, which means I can't test changing the global values, or using log4j2 (for us) and...I guess a log4j.properties file (to affect hadoop?).

TL;DR
Unless I'm seriously misunderstanding things,
 - In a tenant system without the ability to change global configuration files for hadoop and yarn, there is no way to change the logging level.
 - In a system where you have the ability to change the global configuration files, you can make global configuration changes to change log levels.
 - I think this ticket should be closed as "Won't Fix" or something similar.

I greatly desire the community's thoughts, and would love nothing more than to be wrong, b/c right now I suspect all we can do to debug the distributed portions is to, as needed, change logger.debug statements to logger.info statements.

> Debug Logging Not Working within Distributed Applications
> ---------------------------------------------------------
>
>                 Key: PIRK-65
>                 URL: https://issues.apache.org/jira/browse/PIRK-65
>             Project: PIRK
>          Issue Type: Bug
>            Reporter: Ellison Anne Williams
>            Assignee: Walter Ray-Dulany
>
> It appears that debug logging is not working within distributed applications - only within standalone components. 



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