[HBASE-10092] Move to slf4j

• Type: Sub-task
• Status: Closed
• Priority: Critical
• Resolution: Fixed
• Fix Version/s: 2.0.0-beta-1, 2.0.0
• Hadoop Flags: Reviewed

Release Note

We now have slf4j as our front-end. Be careful adding logging from here on out; make sure it slf4j.

From here on out, as us devs go, we need to convert log messages from being 'guarded' -- i.e. surrounded by if (LOG.isDebugEnabled...) -- to instead being parameterized log messages. e.g. the latter rather than the former in the below:

logger.debug("The new entry is "+entry+".");
logger.debug("The new entry is {}.", entry);

See [1] for background on perf benefits.

Note, FATAL log level is not present in slf4j. It is noted as a Marker but won't show in logs as a LEVEL.

1. https://www.slf4j.org/faq.html#logging_performance

• Assignee: Balazs Meszaros
• Reporter: Michael Stack
• Created: 06/Dec/13 00:03
• Updated: 17/Jun/22 04:51
• Resolved: 22/Dec/17 03:25

Description

Allows logging with less friction. See http://logging.apache.org/log4j/2.x/ This rather radical transition can be done w/ minor change given they have an adapter for apache's logging, the one we use. They also have and adapter for slf4j so we likely can remove at least some of the 4 versions of this module our dependencies make use of.

I made a start in attached patch but am currently stuck in maven dependency resolve hell courtesy of our slf4j. Fixing will take some concentration and a good net connection, an item I currently lack. Other TODOs are that will need to fix our little log level setting jsp page – will likely have to undo our use of hadoop's tool here – and the config system changes a little.

I will return to this project soon. Will bring numbers.

Issue Links

• is blocked by: LOG4J2-63 Support configuration from version 1.x log4j.properties
• is depended upon by: LOG4J2-1515 Help Apache HBase project to upgrade from Log4j 1.x to 2.x
• is related to: HBASE-10796 Set default log level as INFO
• is related to: HADOOP-12956 Inevitable Log4j2 migration via slf4j
• is related to: HBASE-19449 Minor logging change in HFileArchiver
• relates to: HBASE-10073 Revert HBASE-9718 (Add a test scope dependency on org.slf4j:slf4j-api to hbase-client)
• relates to: HBASE-2608 Switch to SLF4J
• relates to: HBASE-11334 Migrate to SLF4J as logging interface
• links to: Review Board