Why Does Metric Data Collection Fail?

  1. You can view metric data several minutes after you connect Agents.
  2. If data collection is stopped, the possible causes are as follows:
    • Instance level: Agents are stopped on the Instance tab page.
    • Monitoring item level: Monitoring items are manually disabled on the Monitoring Item tab page.
    • Global level: The Stop Collecting Data Through Bytecode Instrumentation option is enabled on the General Configuration page.
  1. If no data is collected for a long time, the possible causes are as follows:
    • Java 9 prompts that the sql.time class cannot be found.

      Cause analysis: Agents are developed using JDK 1.7. However, after Java 9 modularization, no SQL package is provided by default.

      Occurrence probability: This problem occurs under certain conditions.

      Workaround: Ensure that the component can proactively import java.sql to module-info.java.

    • Java 11 prompts that "Caused by: java.lang.NoClassDefFoundError: sun/misc/Unsafe class cannot be found."

      Cause analysis: Agents are developed using JDK 1.7, but the Java 11 Unsafe class is categorized to a different package.

      Occurrence probability: This problem occurs inevitably.

      Workaround: Ensure that the application can proactively import jdk.unsupported to module-info.java.

    • Java 9 reports an illegal reflective access alarm. (This problem will be solved in versions later than Java 9.)

      Workaround: Set --illegal-access to warn or delete this option.

Parent topic: FAQs