Manual:$wgDebugLogGroups

Details
Set to an array of log group keys to filenames.

If set,   output for that group will go to that file instead of the regular  .

Useful for enabling selective logging in production.

Log destinations may be one of the following:


 * false to completely remove from the output, including from $wgDebugLogFile.


 * string values specifying a filename or URI.


 * associative array with keys:


 * 'destination' desired filename or URI.


 * 'sample' an integer value, specifying a sampling factor (optional)


 * 'level' A \Psr\Log\LogLevel constant, indicating the minimum level log (optional, since 1.25)

When   is set to a non-default value,   will probably be ignored, and the method of configuring log files will be determined by whatever logging system is invoked by  .

Example
This example logs debug messages of group "ConfirmEditExtension" to "debug-ext_confirmedit.log" and those of group "SpamRegex" to "debug-spam.log".

Example:

Advanced example:

Some common debug log groups

 * ,,   - errors
 * - deprecation warnings
 * ,,  /  - cache
 * ,,   - database
 * - all DB queries
 * - response cookies
 * - shell commands
 * ,  - hitting rate limits ( and other)
 * ,  - ResourceLoader
 * ,  - HTTP requests to external services (via the  /  classes)
 * - API
 * ,,   - image-related
 * - job queue
 * ,  - parser
 * - warnings about pages that take long to parse
 * ,  - parser
 * - warnings about pages that take long to parse