Flink Log Overview¶
Log Description¶
Log path:
Run logs of a Flink job: ${BIGDATA_DATA_HOME}/hadoop/data${i}/nm/containerlogs/application_${appid}/container_{$contid}
Note
The logs of executing tasks are stored in the preceding path. After the execution is complete, the Yarn configuration determines whether these logs are gathered to the HDFS directory.
FlinkResource run logs: /var/log/Bigdata/flink/flinkResource
Log archive rules:
FlinkResource run logs:
By default, service logs are backed up each time when the log size reaches 20 MB. A maximum of 20 logs can be reserved without being compressed.
Note
For versions earlier than MRS 3.x, The executor logs are backed up each time when the log size reaches 30 MB. A maximum of 20 logs can be reserved without being compressed.
You can set the log size and number of compressed logs on the Manager page or modify the corresponding configuration items in log4j-cli.properties, log4j.properties, and log4j-session.properties in /opt/client/Flink/flink/conf/ on the client. /opt/client is the client installation directory.
Table 1 FlinkResource log list¶ Type
Name
Description
FlinkResource run logs
checkService.log
Health check log
kinit.log
Initialization log
postinstall.log
Service installation log
prestart.log
Prestart script log
start.log
Startup log
Log Level¶
Table 2 describes the log levels supported by Flink. The priorities of log levels are ERROR, WARN, INFO, and DEBUG in descending order. Logs whose levels are higher than or equal to the specified level are printed. The number of printed logs decreases as the specified log level increases.
Level | Description |
|---|---|
ERROR | Error information about the current event processing |
WARN | Exception information about the current event processing |
INFO | Normal running status information about the system and events |
DEBUG | System information and system debugging information |
To modify log levels, perform the following steps:
Go to the All Configurations page of Flink by referring to Modifying Cluster Service Configuration Parameters.
On the menu bar on the left, select the log menu of the target role.
Select a desired log level.
Save the configuration. In the displayed dialog box, click OK to make the configurations take effect.
Note
After the configuration is complete, you do not need to restart the service. Download the client again for the configuration to take effect.
You can also change the configuration items corresponding to the log level in log4j-cli.properties, log4j.properties, and log4j-session.properties in /opt/client/Flink/flink/conf/ on the client. /opt/client is the client installation directory.
When a job is submitted using a client, a log file is generated in the log folder on the client. The default umask value is 0022. Therefore, the default log permission is 644. To change the file permission, you need to change the umask value. For example, to change the umask value of user omm:
Add umask 0026 to the end of the /home/omm/.baskrc file.
Run the source /home/omm/.baskrc command to make the file permission take effect.
Log Format¶
Type | Format | Example |
|---|---|---|
Run log | <yyyy-MM-dd HH:mm:ss,SSS>|<Log level>|<Name of the thread that generates the log>|<Message in the log>|<Location where the log event occurs> | 2019-06-27 21:30:31,778 | INFO | [flink-akka.actor.default-dispatcher-3] | TaskManager container_e10_1498290698388_0004_02_000007 has started. | org.apache.flink.yarn.YarnFlinkResourceManager (FlinkResourceManager.java:368) |