[jira] [Updated] (SOLR-15630) MDC "prefix labels" should be handled by Layout - not hardcoded in solr code

["Chris M. Hostetter (Jira)" <ji...@apache.org>]

     [ https://issues.apache.org/jira/browse/SOLR-15630?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel ]

Chris M. Hostetter updated SOLR-15630:
--------------------------------------
    Attachment: SOLR-15630.patch
        Status: Open  (was: Open)

The attached patch moves the prefixes into the log4j {{PatternLayout}} using {{%notEmpty}} .

The resulting log files hsould be consistent with previous versions, except that I made a conscious choice to move all the existing whitespace separators between the MDC values inside the {{%notEmpty}} macros, so that the log messages would be more compact when any of the MDC values aren't set - but these can be moved out if people miss the {{[    ]}} blocks from threads that aren't collection/core specific.
----
the java changes were made by hand, the config file changes were made via...
{code}
find -name log4j\*xml | xargs perl ~/tmp/fix-mdc.pl
{code}
{code}
#!/usr/bin/perl -pi
BEGIN {
    %prefix = qw( node_name n
		  collection c
		  shard s
		  replica r
		  core x
		  trace_id t );
}
s<(\s*)\%X\{(.*?)\}><%notEmpty{$1$prefix{$2}:%X{$2}}>g;
{code}

> MDC "prefix labels" should be handled by Layout - not hardcoded in solr code
> ----------------------------------------------------------------------------
>
>                 Key: SOLR-15630
>                 URL: https://issues.apache.org/jira/browse/SOLR-15630
>             Project: Solr
>          Issue Type: Improvement
>      Security Level: Public(Default Security Level. Issues are Public) 
>            Reporter: Chris M. Hostetter
>            Assignee: Chris M. Hostetter
>            Priority: Major
>         Attachments: SOLR-15630.patch
>
>
> Currently, when Solr puts values in the MDC for logging, it always prepends them with a "CHAR" + "COLON" prefix that uniquely identifies what the value is – even though the MDC is a map and every value has a "key" associated with it that identifies what it is, ex...
> {code:java}
>   public static void setCollection(String collection) {
>     if (collection != null) {
>       MDC.put(COLLECTION_PROP, "c:" + collection);
>     } else {
>       MDC.remove(COLLECTION_PROP);
>     }
>   }
> {code}
> This choice evidently traces back to when MDC values where initially added SOLR-6673/SOLR-7590 (when Solr was still using slf4j->JUL IIUC) because that was best (only?) way folks found to ensure that log messages that did _not_ have values for specific MDC keys weren't cluttered with valueless prefixes  even when a log message didn't correspond to a specific collection (or replica, or shard, etc...)
> But with modern log4j, we can use use things like the {{%notEmpty}} syntax to prevent excessive verbosity when MDC values aren't set – allowing us to move the prefixes out of the Solr code and into Solr default log4j configuration – so that users who customize their log4j configuration with things like {{%mdc}} (or JSON logging) can get the "bare" values w/o hardcoded prefixes. (while keeping the exact same default log format ... or even improving it by removing some of the wasted whitespace)
>  



--
This message was sent by Atlassian Jira
(v8.3.4#803005)

---------------------------------------------------------------------
To unsubscribe, e-mail: issues-unsubscribe@solr.apache.org
For additional commands, e-mail: issues-help@solr.apache.org