Change log levels of JobManager and TaskManager to debug a running job - Realtime Compute for Apache Flink - Alibaba Cloud - Realtime Compute for Apache Flink

When INFO level logs do not provide enough information to troubleshoot an issue, you can change the log level to DEBUG. This topic describes how to dynamically adjust the log level for a running job, including its limitations and usage notes.

Background information

The supported log levels are listed in the following table in ascending order of severity.

Level	Description
TRACE	Provides more fine-grained information than `DEBUG`.
DEBUG	Provides detailed information about how the system is operating.
INFO	Provides information about important or notable events.
WARN	Indicates potential system issues.
ERROR	Indicates system errors and exceptions.

Limitations

You can only dynamically set the log level to INFO or DEBUG, as other levels are not supported for this feature.
You can change the log level for the entire JobManager.
You can only change the log level for one TaskManager at a time. To change the level for multiple TaskManagers, you must configure each one individually.

Usage notes

When the log level is set to DEBUG, logs from the DEBUG, INFO, WARN, and ERROR levels are printed.
When the log level is set to INFO, only logs from the INFO, WARN, and ERROR levels are printed.
Changing the log level affects only new log messages.
Enabling DEBUG logs can slightly affect job performance. We recommend keeping the log level set to INFO except when troubleshooting an issue.

Procedure

Log in to the Realtime Compute for Apache Flink console.
In the Actions column of the target workspace, click Console.
In the navigation pane, go to O&M > Deployments.
Click the name of the target deployment.
Click the Logs tab.
On the Running Logs tab, select the running job.
Change the log level for the JobManager or TaskManagers.
- Change the JobManager log level
  1. On the JobManager tab, click Logs.
  2. Click Edit.
  3. Click OK. In the confirmation dialog box that appears with the message The log will then be output in the modified type, click OK.
  4. Select the target log level from the drop-down list.
  5. Click OK.
- Change a TaskManager log level
  1. On the Running TaskManagers tab, find the target TaskManager and click its entry in the Path, ID column.
  2. Click the Logs tab to view the runtime logs for the TaskManager.
  3. Click Edit.
  4. Click OK. In the confirmation dialog box that appears, a message is displayed: The log will then be output in the modified type. Click OK.
  5. Select the target log level from the drop-down list.
  6. After changing the log level, click OK.