Merge pull request #119 from escoem/JENKINS-22791

[JENKINS-22791] Record heap histograms
jenkinsci · Oct 23, 2017 · ea8b5b9 · ea8b5b9
2 parents 6cb4198 + 2563101
commit ea8b5b9
Showing 1 changed file with 97 additions and 0 deletions.
diff --git a/src/main/java/com/cloudbees/jenkins/support/impl/HeapUsageHistogram.java b/src/main/java/com/cloudbees/jenkins/support/impl/HeapUsageHistogram.java
@@ -0,0 +1,97 @@
+package com.cloudbees.jenkins.support.impl;
+
+import com.cloudbees.jenkins.support.AsyncResultCache;
+import com.cloudbees.jenkins.support.api.Component;
+import com.cloudbees.jenkins.support.api.Container;
+import com.cloudbees.jenkins.support.api.Content;
+import edu.umd.cs.findbugs.annotations.NonNull;
+import hudson.Extension;
+import hudson.model.Node;
+import hudson.remoting.Callable;
+import hudson.security.Permission;
+import jenkins.model.Jenkins;
+import org.jenkinsci.remoting.RoleChecker;
+import org.kohsuke.accmod.Restricted;
+import org.kohsuke.accmod.restrictions.NoExternalUse;
+
+import javax.management.InstanceNotFoundException;
+import javax.management.MBeanException;
+import javax.management.MBeanServer;
+import javax.management.MalformedObjectNameException;
+import javax.management.ObjectName;
+import javax.management.ReflectionException;
+import java.io.IOException;
+import java.io.OutputStream;
+import java.lang.management.ManagementFactory;
+import java.util.Collections;
+import java.util.Set;
+import java.util.WeakHashMap;
+import java.util.logging.Level;
+import java.util.logging.Logger;
+
+/**
+ * Heap histogram from master node.
+ */
+@Extension
+@Restricted(NoExternalUse.class)
+public class HeapUsageHistogram extends Component {
+    // first 200 classes so 203 lines required because of the header
+    private static final int MAX = 203;
+
+    private static final Logger logger = Logger.getLogger(HeapUsageHistogram.class.getName());
+
+    @NonNull
+    @Override
+    public Set<Permission> getRequiredPermissions() {
+        return Collections.singleton(Jenkins.ADMINISTER);
+    }
+
+    @NonNull
+    @Override
+    public String getDisplayName() {
+        return "Master Heap Histogram";
+    }
+
+    @Override
+    public void addContents(@NonNull Container result) {
+        result.add(
+            new Content("nodes/master/heap-histogram.txt") {
+                @Override
+                public void writeTo(OutputStream os) throws IOException {
+                    os.write(getLiveHistogram().getBytes("UTF-8"));
+                }
+            }
+        );
+    }
+
+    private String getLiveHistogram() throws IOException {
+        final String raw = getRawLiveHistogram();
+        final String[] lines = raw.split("\n");
+        final int limit = MAX <= lines.length ? MAX : lines.length;
+
+        final StringBuilder bos = new StringBuilder();
+        //starting in 1 because of an empty line
+        for (int i=1; i<limit; i++) {
+            bos.append(lines[i]).append('\n');
+        }
+
+        return bos.toString();
+    }
+
+    private String getRawLiveHistogram() {
+        String result;
+        try {
+            ObjectName objName = new ObjectName("com.sun.management:type=DiagnosticCommand");
+            MBeanServer platform = ManagementFactory.getPlatformMBeanServer();
+            if (platform == null) {
+                return "N/A";
+            }
+            result = (String) platform.invoke(objName, "gcClassHistogram", new Object[] {null}, new String[]{String[].class.getName()});
+        }
+        catch (InstanceNotFoundException | ReflectionException | MBeanException | MalformedObjectNameException e) {
+            logger.log(Level.WARNING,"Could not record heap live histogram.", e);
+            result = "N/A";
+        }
+        return result;
+    }
+}