Memory statistics never collected unless UseDerivedCumulative is used

[kfcss]

Please answer these questions before submitting a bug report.

What version of OpenCensus are you using?

go.opencensus.io v0.23.0

What version of Go are you using?

1.18

What did you do?

Callled

runmetrics.Enable(runmetrics.RunMetricOptions{
		EnableCPU:            true,
		EnableMemory:         true,
	})

What did you expect to see?

That memory metrics were being updated

What did you see instead?

Memory metrics are NOT updated.

Additional context

I think the bug was created with the commit: 49838f2

Metrics are created here:

opencensus-go/plugin/runmetrics/producer.go

Lines 125 to 138 in 06ffb6a

	if options.EnableMemory {
	switch options.UseDerivedCumulative {
	case true:
	producer.memStats, err = newMemStats(producer)
	if err != nil {
	return err
	}
	default:
	producer.deprecatedMemStats, err = newDeprecatedMemStats(producer)
	if err != nil {
	return err
	}
	}
	}

The problem is that p.deprecatedMemStats.read() is never called in func (p *producer) Read():

opencensus-go/plugin/runmetrics/producer.go

Lines 167 to 177 in 06ffb6a

	func (p *producer) Read() []*metricdata.Metric {
	if p.memStats != nil {
	p.memStats.read()
	}
	if p.cpuStats != nil {
	p.cpuStats.read()
	}
	return p.reg.Read()
	}