Consider adding JVM metric for open file descriptors Semantic Conventions

[schmikei]

Propose new conventions

I'd like to add this metric to the java-contrib project.

  - bean: java.lang:type=OperatingSystem
    mapping:
      OpenFileDescriptorCount:
        metric: jvm.fd.open
        unit: 1
        desc: open file descriptors

Happy to discuss naming conventions on these as well but would like to collect this information!

I believe that this metric would be useful for monitoring resource usage and detecting potential file descriptor leaks and should be recommended metric.

Apologies if there was already discussion on adding this metric I just did not see it in the current list found here: https://opentelemetry.io/docs/specs/semconv/runtime/jvm-metrics/

[trask]

hi @schmikei!

let's watch #1798, and once they decide on a name, we can reuse that same name under jvm.*, similar to how we have jvm.cpu.time reflecting process.cpu.time

[trask]

@schmikei I'm not finding the OpenFileDescriptorCount metric you're showing in the screenshot.

I looked in

• https://docs.oracle.com/en/java/javase/17/docs/api/java.management/java/lang/management/OperatingSystemMXBean.html
• https://docs.oracle.com/en/java/javase/17/docs/api/jdk.management/com/sun/management/OperatingSystemMXBean.html

[schmikei]

@trask

They can be found here:

https://docs.oracle.com/en/java/javase/17/docs/api/jdk.management/com/sun/management/UnixOperatingSystemMXBean.html

They are unix based only since Windows doesn't use file descriptors on the kernel layer