High memory usage for generate metrics

[Enotze]

Use promphp/prometheus_client_php version 2.7.1 and APCng

I am use histograms with name 'sdui_component_time_generation_bucket' and labels 'component', 'state_id'

Components count is 100
State_id count is 100
Total number of variants 100 * 100 = 10 000
Generated ~ 128 777 rows for histograms

And for response with 15.1 MB

PHP use 156 MB

I think it is because all metrics collect to one array
\Prometheus\Storage\APCng::collect

And all samples in one array
\Prometheus\Storage\APCng::collectHistograms

I think solution it is use php generator