Fork process models for metric batch reader do not work

[lzchen]

and when a new process is not created (simply a new fork is created).

When does this happen?

One thing I am still thinking about is how do I do the same for PeriodicExportingMetricReader? Unlike tracing/logging where the events are received by processor, the PMR collects them with collect function. There is nothing like emit or on_start/on_end where I can check if the pids to see the fork hook is invoked and invoke if not.

Originally posted by @srikanthccv in https://github.com/open-telemetry/opentelemetry-python/issues/2277#issuecomment-1148999039