Question

I’m using logback as my logging framework and have a couple of jobs that run the same main function with different parameters and would like to create a log file for each job and name the log file with the job’s name.

For example, if I had jobs a,b,c that all run MyClass.main() but with different parameters, then I’d like to see a-{date}.log, b-{date}.log, c-{date}.log.

I can achieve the {date} part by specifying a <fileNamePattern>myjob-%d{yyyy-MM-dd}.log</fileNamePattern> in my logback.xml, but I’m not sure how to (or if it is even possible) create the prefix of the file names dynamically (to be the job’s name).

Is there a way to dynamically name logfiles in logback? Is there another logging framework that makes this possible?

As a follow up question, am I just taking a bad approach for having multiple jobs that call the same main function with different parameters and wanting a log file named after each job? If so is there a standard/best practice solution for this case?

EDIT: The reason why I want to name each log file after the name of the job is that each job naturally defines a “unit of work” and it is easier for me to find the appropriate log file in case one of the job fails. I could simply use a rolling log file for jobs a,b,c but I found it harder for me to look through the logs and pinpoint where each job started and ended.

Answer 1

Is there a way to dynamically name logfiles in logback? Is there another logging framework that makes this possible?

I don’t believe this is possible using the out of the box appenders (File, RollingFile etc) configured by a standard logback.xml file. To do what you want, you would need to dynamically create appenders on the fly and assign loggers to different appenders. Or you would need to invent a new appender that was smart enough to write to multiple files at the same time, based on the logger name.

am I just taking a bad approach for having multiple jobs that call the same main function with different parameters and wanting a log file named after each job?

The authors of logback address this issue and slightly discourage it in the section on Mapped Diagnostic Context

A possible but slightly discouraged approach to differentiate the logging output of one client from another consists of instantiating a new and separate logger for each client. This technique promotes the proliferation of loggers and may increase their management overhead. … A lighter technique consists of uniquely stamping each log request servicing a given client.

Then they go on to discuss mapped diagnostic contexts as a solution to this problem. They give an example of a NumberCruncherServer which is crunching numbers, for various clients in various threads simultaneously. By setting the mapped diagnostic context and an appropriate logging pattern it becomes easy to determine which log events originated from which client. Then you could simply use a grep tool to separate logging events of interest into a separate file for detailed analysis.