1 files changed, 20 insertions, 1 deletions
diff --git a/container-disc/src/main/java/com/yahoo/container/jdisc/metric/MetricUpdater.java b/container-disc/src/main/java/com/yahoo/container/jdisc/metric/MetricUpdater.java
index e23844c65b7..1c6e85a177a 100644
--- a/container-disc/src/main/java/com/yahoo/container/jdisc/metric/MetricUpdater.java
+++ b/container-disc/src/main/java/com/yahoo/container/jdisc/metric/MetricUpdater.java
@@ -3,6 +3,7 @@ package com.yahoo.container.jdisc.metric;
 
 import java.util.Timer;
 import java.util.TimerTask;
+import java.nio.file.DirectoryStream;
 import java.nio.file.Path;
 import java.nio.file.Paths;
 import java.nio.file.Files;
@@ -26,7 +27,8 @@ public class MetricUpdater extends AbstractComponent {
     private static final String MANHATTAN_FREE_MEMORY_BYTES = "mem.heap.free";
     private static final String MANHATTAN_USED_MEMORY_BYTES = "mem.heap.used";
     private static final String MANHATTAN_TOTAL_MEMORY_BYTES = "mem.heap.total";
-    private static final String MEMORY_MAPPINGS_COUNT = "memory_mappings_count";
+    private static final String MEMORY_MAPPINGS_COUNT = "jdisc.memory_mappings";
+    private static final String OPEN_FILE_DESCRIPTORS = "jdisc.open_file_descriptors";
 
     private final Metric metric;
     private final Timer timer = new Timer();
@@ -65,6 +67,7 @@ public class MetricUpdater extends AbstractComponent {
             metric.set(MANHATTAN_USED_MEMORY_BYTES, usedMemory, null);
             metric.set(MANHATTAN_TOTAL_MEMORY_BYTES, totalMemory, null);
             metric.set(MEMORY_MAPPINGS_COUNT, count_mappings(), null);
+            metric.set(OPEN_FILE_DESCRIPTORS, count_open_files(), null);
         }
 
         // Note: Linux-specific
@@ -83,6 +86,22 @@ public class MetricUpdater extends AbstractComponent {
             }
             return count;
         }
+
+        // Note: Linux-specific
+        private long count_open_files() {
+            long count = 0;
+            try {
+                Path p = Paths.get("/proc/self/fd");
+                try (DirectoryStream<Path> stream = Files.newDirectoryStream(p)) {
+                    for (Path entry : stream) {
+                        ++count;
+                    }
+                }
+            } catch (Exception e) {
+                System.err.println("Could not read /proc/self/fd: " + e);
+            }
+            return count;
+        }
     }
 }