[GEODE-9476] VMStats processCpuTime, fdLimit, and fdsOpen will always be zero on java 16 and later

• Type: Bug
• Status: Closed
• Priority: Major
• Resolution: Fixed
• Fix Version/s: 1.15.0
• Component/s: statistics
• Labels: Java16 Java17
• Assignee: Unassigned
• Reporter: Darrel Schneider
• Created: 28/Jul/21 20:35
• Updated: 22/Jun/22 20:46
• Resolved: 28/Apr/22 19:40

Description

VMStats processCpuTime, fdLimit, and fdsOpen will always be zero on java 16 and later.
This is because it calls Method.setAccessible which is not allowed under normal conditions starting with java 16 (see: https://softwaregarden.dev/en/posts/new-java/illegal-access-in-java-16).

A workaround for this bug is to start the jvm with --illegal-access=permit

The setAccessible call is in the static initializer for: org.apache.geode.internal.stats50.VMStats50

It turns out the following works for calling processCpuTime:

        OperatingSystemMXBean osBean = ManagementFactory.getOperatingSystemMXBean();
        com.sun.management.OperatingSystemMXBean sunBean = (com.sun.management.OperatingSystemMXBean) osBean;
        System.out.println("getProcessCpuTime=" + sunBean.getProcessCpuTime());

so we can get rid of the setAccessible call