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commons-logging

commons-logging provides a custom log4j appender to manage log files

Overview

Logging has following challenges

  1. Disk becomes fully consumed by logs. This results in server stalling, and loss of logs.
  2. We primarily use Log4j

    1. Log4j RollingFileAppender renames older files

      1. So this can fool Greylog's Sidecar tool into thinking that new log files have been created. So Sidecar may send duplicate logs to Greylog
      2. It does not name files as per date/time

    2. Log4j DailyRollingFileAppender only renames files as per date/time. It does not take care of disk utilization

  3. There is no combination of the above which does this in a meaningful manner.

Thus, we have created our own Log4j appender in the commons-logging library.

Usage

log4j.properties

Add the following to the log4j.properties file in the project

#Worked with 2.17 version
log4j.rootLogger=INFO, file

#Specify our class to be used as the appender
log4j.appender.file=com.increff.commons.logging.SmartFileAppender

#Maximum file size which triggers rolling - 10MB
log4j.appender.file.MaxFileSize=10000000

#Maximum total log file disk usage - 1GB
log4j.appender.file.MaxDiskUsage=1000000000

#Log file name
log4j.appender.file.File=app.log
log4j.appender.file.BufferedIO=true
log4j.appender.file.layout=org.apache.log4j.PatternLayout  
log4j.appender.file.layout.ConversionPattern=%d [%t] %-5p (%F:%L) - %m%n

pom.xml

To use commons-logging, include the following in the project's pom.xml

<dependency>
    <groupId>com.increff.commons</groupId>
    <artifactId>commons-logging</artifactId>
    <version>1.7</version>
</dependency>

Behavior

  1. The actual log files are named as app.<yyyy-MM-dd-HH-mm>.log For example, app.2020-04-27-14-01.log
  2. The log file rotation happens when either of the following conditions is satisfied
    1. Current log file size exceeds MaxFileSize
    2. The day has changed
  3. If too many logs are getting generated, then the file will get rotated only when the minute changes
  4. When the total disk consumed by all log files exceeds MaxDiskUsage, then the oldest files are deleted to bring the usage under MaxDiskUsage

Parameters

Name Required Default Example Purpose
File yes NA app.log Name of the log file. Actual file is named as <yyyy-MM-dd-HH-mm>.log
BufferedIO no false true Whether to use buffering or not. This parameter is recommended to improve performance.
BufferSize no 8*1024 (8Kb) 16000 bytes to buffer before flushing. This parameter can be left to default.
MaxFileSize no 10000000 (10MB) 50000000 (50 MB) Disk usage by current log file, before a new log file is created. This parameter may not behonored perfectly if logs generated per minute exceed this limit. Value under 1MB will be ignored.
MaxDiskUsage no 10000000000 (10 GB) 50000000000 (50 GB) Disk usage by all log files, before oldest files are deleted.Value under 50MB will be ignored

License

Copyright (c) Increff

Licensed under the Apache License, Version 2.0 (the "License"); you may not use this file except in compliance with the License. You may obtain a copy of the License at

http://www.apache.org/licenses/LICENSE-2.0

Unless required by applicable law or agreed to in writing, software distributed under the License is distributed on an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the License for the specific language governing permissions and limitations under the License.