Set up resource-usage plugin api so that serverside emits host available memory.

Author: nimpo

jupyter_resource_usage/api.py

@@ -46,6 +46,8 @@ async def get(self):
             except (psutil.NoSuchProcess, psutil.AccessDenied) as e:
                 pass
 
+        available = psutil.virtual_memory().available
+
         if callable(config.mem_limit):
             mem_limit = config.mem_limit(rss=rss, pss=pss)
         else:  # mem_limit is an Int
@@ -58,6 +60,7 @@ async def get(self):
             )
 
         metrics = {"rss": rss, "limits": limits}
+        metrics["mem_avail"] = available
         if pss is not None:
             metrics["pss"] = pss
 

jupyter_resource_usage/config.py

@@ -54,7 +54,10 @@ class ResourceUseDisplay(Configurable):
 
     system_memory_metrics = List(
         trait=PSUtilMetric(),
-        default_value=[{"name": "virtual_memory", "attribute": "total"}],
+        default_value=[
+            {"name": "virtual_memory", "attribute": "total"},
+            {"name": "virtual_memory", "attribute": "available"}
+        ],
     )
 
     process_cpu_metrics = List(