Added defensive code for scenario where thread id <= 0

Signed-off-by: Doug Hoard <[email protected]>

Author: dhoard

simpleclient_hotspot/src/main/java/io/prometheus/client/hotspot/ThreadExports.java

@@ -3,13 +3,13 @@
 import io.prometheus.client.Collector;
 import io.prometheus.client.CounterMetricFamily;
 import io.prometheus.client.GaugeMetricFamily;
-import io.prometheus.client.SampleNameFilter;
 import io.prometheus.client.Predicate;
 
 import java.lang.management.ManagementFactory;
 import java.lang.management.ThreadInfo;
 import java.lang.management.ThreadMXBean;
 import java.util.ArrayList;
+import java.util.Arrays;
 import java.util.Collections;
 import java.util.HashMap;
 import java.util.List;
@@ -36,13 +36,16 @@
  */
 public class ThreadExports extends Collector {
 
+  public static final String UNKNOWN = "UNKNOWN";
+
+  public static final String JVM_THREADS_STATE = "jvm_threads_state";
+
   private static final String JVM_THREADS_CURRENT = "jvm_threads_current";
   private static final String JVM_THREADS_DAEMON = "jvm_threads_daemon";
   private static final String JVM_THREADS_PEAK = "jvm_threads_peak";
   private static final String JVM_THREADS_STARTED_TOTAL = "jvm_threads_started_total";
   private static final String JVM_THREADS_DEADLOCKED = "jvm_threads_deadlocked";
   private static final String JVM_THREADS_DEADLOCKED_MONITOR = "jvm_threads_deadlocked_monitor";
-  private static final String JVM_THREADS_STATE = "jvm_threads_state";
 
   private final ThreadMXBean threadBean;
 
@@ -109,35 +112,51 @@ void addThreadMetrics(List<MetricFamilySamples> sampleFamilies, Predicate<String
               "Current count of threads by state",
               Collections.singletonList("state"));
 
-      Map<Thread.State, Integer> threadStateCounts = getThreadStateCountMap();
-      for (Map.Entry<Thread.State, Integer> entry : threadStateCounts.entrySet()) {
+      Map<String, Integer> threadStateCounts = getThreadStateCountMap();
+      for (Map.Entry<String, Integer> entry : threadStateCounts.entrySet()) {
         threadStateFamily.addMetric(
-                Collections.singletonList(entry.getKey().toString()),
+                Collections.singletonList(entry.getKey()),
                 entry.getValue()
         );
       }
       sampleFamilies.add(threadStateFamily);
     }
   }
 
-  private Map<Thread.State, Integer> getThreadStateCountMap() {
+  private Map<String, Integer> getThreadStateCountMap() {
+    long[] threadIds = threadBean.getAllThreadIds();
+
+    // Code to remove any thread id values <= 0
+    int writePos = 0;
+    for (int i = 0; i < threadIds.length; i++) {
+      if (threadIds[i] > 0) {
+        threadIds[writePos++] = threadIds[i];
+      }
+    }
+
+    int numberOfInvalidThreadIds = threadIds.length - writePos;
+    threadIds = Arrays.copyOf(threadIds, writePos);
+
     // Get thread information without computing any stack traces
-    ThreadInfo[] allThreads = threadBean.getThreadInfo(threadBean.getAllThreadIds(), 0);
+    ThreadInfo[] allThreads = threadBean.getThreadInfo(threadIds, 0);
 
     // Initialize the map with all thread states
-    HashMap<Thread.State, Integer> threadCounts = new HashMap<Thread.State, Integer>();
+    HashMap<String, Integer> threadCounts = new HashMap<String, Integer>();
     for (Thread.State state : Thread.State.values()) {
-      threadCounts.put(state, 0);
+      threadCounts.put(state.name(), 0);
     }
 
     // Collect the actual thread counts
     for (ThreadInfo curThread : allThreads) {
       if (curThread != null) {
         Thread.State threadState = curThread.getThreadState();
-        threadCounts.put(threadState, threadCounts.get(threadState) + 1);
+        threadCounts.put(threadState.name(), threadCounts.get(threadState.name()) + 1);
       }
     }
 
+    // Add the thread count for invalid thread ids
+    threadCounts.put(UNKNOWN, numberOfInvalidThreadIds);
+
     return threadCounts;
   }
 

simpleclient_hotspot/src/test/java/io/prometheus/client/hotspot/ThreadExportsTest.java

@@ -1,13 +1,17 @@
 package io.prometheus.client.hotspot;
 
+import io.prometheus.client.Collector.MetricFamilySamples;
 import io.prometheus.client.CollectorRegistry;
 import org.junit.Before;
 import org.junit.Test;
 import org.mockito.Mockito;
 
 import java.lang.management.ThreadInfo;
 import java.lang.management.ThreadMXBean;
-import java.util.Arrays;
+import java.util.HashMap;
+import java.util.List;
+import java.util.Map;
+import java.util.concurrent.CountDownLatch;
 
 import static org.junit.Assert.assertEquals;
 import static org.mockito.Mockito.when;
@@ -97,4 +101,98 @@ public void testThreadPools() {
                     "jvm_threads_state", STATE_LABEL, STATE_TERMINATED_LABEL),
             .0000001);
   }
+
+  @Test
+  public void testInvalidThreadIds() {
+    ThreadExports threadExports = new ThreadExports();
+
+    // Number of threads to create with invalid thread ids
+    int numberOfInvalidThreadIds = 2;
+
+    // Get the current thread state counts
+    Map<String, Double> expectedThreadStateCountMap = new HashMap<String, Double>();
+    List<MetricFamilySamples> metricFamilySamplesList = threadExports.collect();
+    for (MetricFamilySamples metricFamilySamples : metricFamilySamplesList) {
+      if (ThreadExports.JVM_THREADS_STATE.equals(metricFamilySamples.name)) {
+        for (MetricFamilySamples.Sample sample : metricFamilySamples.samples) {
+          expectedThreadStateCountMap.put(ThreadExports.JVM_THREADS_STATE + "-" + sample.labelValues.get(0), sample.value);
+        }
+      }
+    }
+
+    // Add numberOfInvalidThreadIds to the expected UNKNOWN thread state count
+    expectedThreadStateCountMap.put(
+      ThreadExports.JVM_THREADS_STATE + "-" + ThreadExports.UNKNOWN,
+      expectedThreadStateCountMap.get(
+        ThreadExports.JVM_THREADS_STATE + "-" + ThreadExports.UNKNOWN) + numberOfInvalidThreadIds);
+
+    final CountDownLatch countDownLatch = new CountDownLatch(numberOfInvalidThreadIds);
+
+    try {
+      // Create and start threads with invalid thread ids (id=0, id=-1, etc.)
+      for (int i = 0; i < numberOfInvalidThreadIds; i++) {
+        new TestThread(-i, new TestRunnable(countDownLatch)).start();
+      }
+
+      // Get the current thread state counts
+      Map<String, Double> actualThreadStateCountMap = new HashMap<String, Double>();
+      metricFamilySamplesList = threadExports.collect();
+      for (MetricFamilySamples metricFamilySamples : metricFamilySamplesList) {
+        if (ThreadExports.JVM_THREADS_STATE.equals(metricFamilySamples.name)) {
+          for (MetricFamilySamples.Sample sample : metricFamilySamples.samples) {
+            actualThreadStateCountMap.put(ThreadExports.JVM_THREADS_STATE + "-" + sample.labelValues.get(0), sample.value);
+          }
+        }
+      }
+
+      // Assert that we have the same number of thread states
+      assertEquals(expectedThreadStateCountMap.size(), actualThreadStateCountMap.size());
+
+      // Check each thread state count
+      for (String threadState : expectedThreadStateCountMap.keySet()) {
+        double expectedThreadStateCount = expectedThreadStateCountMap.get(threadState);
+        double actualThreadStateCount = actualThreadStateCountMap.get(threadState);
+
+        // Assert the expected and actual thread count states are equal
+        assertEquals(expectedThreadStateCount, actualThreadStateCount, 0.0);
+      }
+    } finally {
+      for (int i = 0; i < numberOfInvalidThreadIds; i++) {
+        countDownLatch.countDown();
+      }
+    }
+  }
+
+  private class TestThread extends Thread {
+
+    private long id;
+
+    public TestThread(long id, Runnable runnable) {
+      super(runnable);
+      setDaemon(true);
+      this.id = id;
+    }
+
+    public long getId() {
+      return this.id;
+    }
+  }
+
+  private class TestRunnable implements Runnable {
+
+    private CountDownLatch countDownLatch;
+
+    public TestRunnable(CountDownLatch countDownLatch) {
+      this.countDownLatch = countDownLatch;
+    }
+
+    @Override
+    public void run() {
+      try {
+        countDownLatch.await();
+      } catch (InterruptedException e) {
+        // DO NOTHING
+      }
+    }
+  }
 }