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LOGGING.md

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Logging

The Top4J Java Agent can be configured to log performance metrics to the local file system.

This feature is disabled by default but can be easily enabled via the Top4J configuration property stats.logger.enabled=true.

The stats.logger.enabled override property can be set in one of two ways:

  1. By creating a custom top4j.properties file containing stats.logger.enabled=true - see the Top4J Configuration documentation for more details.
  2. By adding an additional argument to the java -javaagent command-line argument, for example....
java -javaagent:<path-to-top4j-jar>/top4j-javaagent-0.0.8.jar=stats.logger.enabled=true <java-class-name>

The Top4J stats logger will log to a directory called top4j-stats within the JVMs current working directory by default. However, the default location can be overridden via the Top4J configuration property stats.logger.directory, for example....

java -javaagent:<path-to-top4j-jar>/top4j-javaagent-0.0.8.jar=stats.logger.enabled=true,stats.logger.directory=/var/log/top4j-stats <java-class-name>

NOTE: Make sure the stats.logger.directory is writable by the Java process owner.

The Top4J stats logger creates one log file per Top4J MBean per day. The stats (MBean attributes) are recorded as comma-separated values (CSV) by default. The stats log files are automatically rolled at midnight.

Here is an example Top4J stats file listing....

-bash-4.1$ ls -1 *20190917.csv
AgentStats.20190917.csv
BlockedThread-1.20190917.csv
BlockedThread-10.20190917.csv
BlockedThread-2.20190917.csv
BlockedThread-3.20190917.csv
BlockedThread-4.20190917.csv
BlockedThread-5.20190917.csv
BlockedThread-6.20190917.csv
BlockedThread-7.20190917.csv
BlockedThread-8.20190917.csv
BlockedThread-9.20190917.csv
GCStats.20190917.csv
HeapStats.20190917.csv
MemoryStats.20190917.csv
ThreadStats.20190917.csv
TopThread-1.20190917.csv
TopThread-10.20190917.csv
TopThread-2.20190917.csv
TopThread-3.20190917.csv
TopThread-4.20190917.csv
TopThread-5.20190917.csv
TopThread-6.20190917.csv
TopThread-7.20190917.csv
TopThread-8.20190917.csv
TopThread-9.20190917.csv

Here are some example Top4J stats....

-bash-4.1$ head ThreadStats.20190917.csv
Timestamp,BlockedThreadCount,CpuUsage,MBeanCpuTime,RunnableThreadCount,SysCpuUsage,ThreadCount,TimedWaitingThreadCount,UserCpuUsage,WaitingThreadCount
2019-09-17T00:00:02.685+0100,999,0.8090,473.8873,3,0.1449,1007,2,0.6641,3
2019-09-17T00:01:02.407+0100,999,0.5729,315.9774,3,0.1210,1007,2,0.4519,3
2019-09-17T00:02:02.455+0100,999,0.6128,345.2138,3,0.1131,1007,2,0.4996,3
2019-09-17T00:03:02.450+0100,999,0.6369,357.5654,3,0.1035,1007,2,0.5334,3
2019-09-17T00:04:02.400+0100,999,0.5635,314.5569,3,0.0965,1007,2,0.4670,3
2019-09-17T00:05:02.755+0100,999,0.9344,570.6357,3,0.1718,1007,2,0.7626,3
2019-09-17T00:06:02.343+0100,999,0.5960,265.6631,3,0.0933,1007,2,0.5027,3
2019-09-17T00:07:02.400+0100,999,0.5593,314.1110,3,0.1097,1007,2,0.4496,3
2019-09-17T00:08:02.461+0100,999,0.6450,368.6486,3,0.1289,1007,2,0.5162,3