Hi all, There have been a few reports lately (On JIRA [1] and on Slack) from users regarding inconsistent loggers used across Beam's modules.
While we use SLF4J, different modules use a different logger behind it (JUL, log4j, etc) So when people add a log4j.properties file to their classpath for instance, they expect this to affect all of their dependencies on Beam modules, but it doesn’t and they miss out on some logs they thought they would see. I think we should strive for consistency in which logger is used behind SLF4J, and try to enforce this in our modules. I for one think it should be slf4j-log4j. However, if performance of logging is critical we might want to consider logback. Note: SLF4J will still be the facade for logging across the project. The only change would be the logger SLF4J delegates to. Once we have something like this it would also be useful to add documentation on logging in Beam to the website. [1] https://issues.apache.org/jira/browse/BEAM-1757
