just committing the memory monitoring test code that I wrote elsewhere.

Still needs a lot more work before this can be integrated into Hudson.

git-svn-id: https://hudson.dev.java.net/svn/hudson/trunk/hudson/main@13089 71c3de6d-444a-0410-be80-ed276b4c234a

core/src/main/java/hudson/model/MemoryUsageMonitor.java

+package hudson.model;
+
+import hudson.triggers.SafeTimerTask;
+
+import java.lang.management.MemoryPoolMXBean;
+import java.lang.management.MemoryType;
+import java.lang.management.MemoryUsage;
+import java.lang.management.ManagementFactory;
+import java.util.List;
+import java.util.ArrayList;
+
+/**
+ * TODO:
+ * @author Kohsuke Kawaguchi
+ */
+public class MemoryUsageMonitor extends SafeTimerTask {
+    class MemoryGroup {
+        private final List<MemoryPoolMXBean> pools = new ArrayList<MemoryPoolMXBean>();
+
+        MemoryGroup(List<MemoryPoolMXBean> pools, MemoryType type) {
+            for (MemoryPoolMXBean pool : pools) {
+                if (pool.getType() == type)
+                    this.pools.add(pool);
+            }
+        }
+
+        public String metrics() {
+            long used = 0;
+            long max = 0;
+            long cur = 0;
+            for (MemoryPoolMXBean pool : pools) {
+                MemoryUsage usage = pool.getCollectionUsage();
+                if(usage==null) continue;   // not available
+                used += usage.getUsed();
+                max  += usage.getMax();
+
+                usage = pool.getUsage();
+                if(usage==null) continue;   // not available
+                cur += usage.getUsed();
+            }
+
+            // B -> KB
+            used /= 1024;
+            max /= 1024;
+            cur /= 1024;
+
+            return String.format("%d/%d/%d (%d%%)",used,cur,max,used*100/max);
+        }
+    }
+
+    private final MemoryGroup heap;
+    private final MemoryGroup nonHeap;
+
+    public MemoryUsageMonitor() {
+        List<MemoryPoolMXBean> pools = ManagementFactory.getMemoryPoolMXBeans();
+        heap = new MemoryGroup(pools, MemoryType.HEAP);
+        nonHeap = new MemoryGroup(pools, MemoryType.NON_HEAP);
+    }
+
+    protected void doRun() {
+        System.out.printf("%s\t%s\n", heap.metrics(), nonHeap.metrics());
+    }
+}