Merge

src/hotspot/share/jfr/periodic/jfrPeriodic.cpp

@@ -54,6 +54,7 @@
 #include "runtime/arguments.hpp"
 #include "runtime/flags/jvmFlag.hpp"
 #include "runtime/globals.hpp"
+#include "runtime/interfaceSupport.inline.hpp"
 #include "runtime/os.hpp"
 #include "runtime/os_perf.hpp"
 #include "runtime/thread.inline.hpp"
@@ -174,7 +175,13 @@ TRACE_REQUEST_FUNC(CPULoad) {
   double u = 0; // user time
   double s = 0; // kernel time
   double t = 0; // total time
-  int ret_val = JfrOSInterface::cpu_loads_process(&u, &s, &t);
+  int ret_val = OS_ERR;
+  {
+    // Can take some time on certain platforms, especially under heavy load.
+    // Transition to native to avoid unnecessary stalls for pending safepoint synchronizations.
+    ThreadToNativeFromVM transition((JavaThread*)Thread::current());
+    ret_val = JfrOSInterface::cpu_loads_process(&u, &s, &t);
+  }
   if (ret_val == OS_ERR) {
     log_debug(jfr, system)( "Unable to generate requestable event CPULoad");
     return;
@@ -248,7 +255,13 @@ TRACE_REQUEST_FUNC(SystemProcess) {
 
 TRACE_REQUEST_FUNC(ThreadContextSwitchRate) {
   double rate = 0.0;
-  int ret_val = JfrOSInterface::context_switch_rate(&rate);
+  int ret_val = OS_ERR;
+  {
+    // Can take some time on certain platforms, especially under heavy load.
+    // Transition to native to avoid unnecessary stalls for pending safepoint synchronizations.
+    ThreadToNativeFromVM transition((JavaThread*)Thread::current());
+    ret_val = JfrOSInterface::context_switch_rate(&rate);
+  }
   if (ret_val == OS_ERR) {
     log_debug(jfr, system)( "Unable to generate requestable event ThreadContextSwitchRate");
     return;

src/java.base/share/classes/java/security/Provider.java

@@ -868,7 +868,7 @@ public abstract class Provider extends Properties {
     // For backward compatibility, the registration ordering of
     // SecureRandom (RNG) algorithms needs to be preserved for
     // "new SecureRandom()" calls when this provider is used
-    private transient Set<Service> prngServices;
+    private transient Set<String> prngAlgos;
 
     // Map<ServiceKey,Service>
     // used for services added via legacy methods, init on demand
@@ -1089,7 +1089,7 @@ public abstract class Provider extends Properties {
         legacyChanged = false;
         servicesChanged = false;
         serviceSet = null;
-        prngServices = null;
+        prngAlgos = null;
         super.clear();
         putId();
     }
@@ -1221,7 +1221,7 @@ public abstract class Provider extends Properties {
                 s.className = className;
 
                 if (type.equals("SecureRandom")) {
-                    updateSecureRandomEntries(true, s);
+                    updateSecureRandomEntries(true, s.algorithm);
                 }
             } else { // attribute
                 // e.g. put("MessageDigest.SHA-1 ImplementedIn", "Software");
@@ -1383,25 +1383,25 @@ public abstract class Provider extends Properties {
         synchronized (this) {
             putPropertyStrings(s);
             if (type.equals("SecureRandom")) {
-                updateSecureRandomEntries(true, s);
+                updateSecureRandomEntries(true, s.algorithm);
             }
         }
     }
 
-    private void updateSecureRandomEntries(boolean doAdd, Service s) {
+    // keep tracks of the registered secure random algos and store them in order
+    private void updateSecureRandomEntries(boolean doAdd, String s) {
         Objects.requireNonNull(s);
         if (doAdd) {
-            if (prngServices == null) {
+            if (prngAlgos == null) {
-                prngServices = new LinkedHashSet<Service>();
+                prngAlgos = new LinkedHashSet<String>();
             }
-            prngServices.add(s);
+            prngAlgos.add(s);
         } else {
-            prngServices.remove(s);
+            prngAlgos.remove(s);
         }
 
         if (debug != null) {
-            debug.println((doAdd? "Add":"Remove") + " SecureRandom algo " +
+            debug.println((doAdd? "Add":"Remove") + " SecureRandom algo " + s);
-                s.getAlgorithm());
         }
     }
 
@@ -1411,12 +1411,15 @@ public abstract class Provider extends Properties {
         checkInitialized();
 
         if (legacyChanged) {
-            prngServices = null;
+            prngAlgos = null;
             ensureLegacyParsed();
         }
 
-        if (prngServices != null && !prngServices.isEmpty()) {
+        if (prngAlgos != null && !prngAlgos.isEmpty()) {
-            return prngServices.iterator().next();
+            // IMPORTANT: use the Service obj returned by getService(...) call
+            // as providers may override putService(...)/getService(...) and
+            // return their own Service objects
+            return getService("SecureRandom", prngAlgos.iterator().next());
         }
 
         return null;
@@ -1516,7 +1519,7 @@ public abstract class Provider extends Properties {
         synchronized (this) {
             removePropertyStrings(s);
             if (type.equals("SecureRandom")) {
-                updateSecureRandomEntries(false, s);
+                updateSecureRandomEntries(false, s.algorithm);
             }
         }
     }

test/hotspot/jtreg/ProblemList.txt

@@ -143,7 +143,7 @@ vmTestbase/nsk/jvmti/scenarios/jni_interception/JI05/ji05t001/TestDescription.ja
 vmTestbase/nsk/jvmti/scenarios/jni_interception/JI06/ji06t001/TestDescription.java 8219652 aix-ppc64
 vmTestbase/nsk/jvmti/SetJNIFunctionTable/setjniftab001/TestDescription.java 8219652 aix-ppc64
 
-vmTestbase/gc/lock/jni/jnilock002/TestDescription.java 8208243,8192647 generic-all
+vmTestbase/gc/lock/jni/jnilock002/TestDescription.java 8192647 generic-all
 
 vmTestbase/jit/escape/LockCoarsening/LockCoarsening001.java 8148743 generic-all
 vmTestbase/jit/escape/LockCoarsening/LockCoarsening002.java 8208259 generic-all

test/hotspot/jtreg/compiler/unsafe/TestUnsafeUnalignedSwap.java

@@ -4,9 +4,7 @@
  *
  * This code is free software; you can redistribute it and/or modify it
  * under the terms of the GNU General Public License version 2 only, as
- * published by the Free Software Foundation. Alibaba designates this
+ * published by the Free Software Foundation.
- * particular file as subject to the "Classpath" exception as provided
- * by Oracle in the LICENSE file that accompanied this code.
  *
  * This code is distributed in the hope that it will be useful, but WITHOUT
  * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
@@ -18,6 +16,9 @@
  * 2 along with this work; if not, write to the Free Software Foundation,
  * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
  *
+ * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
+ * or visit www.oracle.com if you need additional information or have any
+ * questions.
  */
 
 /* @test

test/hotspot/jtreg/vmTestbase/nsk/share/gc/lock/jni/BooleanArrayCriticalLocker.cpp

@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2007, 2019, Oracle and/or its affiliates. All rights reserved.
+ * Copyright (c) 2007, 2020, Oracle and/or its affiliates. All rights reserved.
  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
  *
  * This code is free software; you can redistribute it and/or modify it
@@ -56,13 +56,15 @@ JNIEXPORT jboolean JNICALL Java_nsk_share_gc_lock_jni_BooleanArrayCriticalLocker
   start_time = time(NULL);
   enterTime /= 1000;
   current_time = 0;
-        while (current_time - start_time < enterTime) {
+  while (difftime(current_time, start_time) < enterTime) {
+    hash = JNI_TRUE;
     pa = (jboolean*) ec_jni->GetPrimitiveArrayCritical(arr, NULL, TRACE_JNI_CALL);
     if (pa != NULL) {
-                        for (i = 0; i < size; ++i)
+      for (i = 0; i < size; ++i) {
         hash ^= pa[i];
+      }
     } else {
-                        hash = JNI_FALSE;
+      jni_env->FatalError("GetPrimitiveArrayCritical returned NULL");
     }
     mssleep((long) sleepTime);
     ec_jni->ReleasePrimitiveArrayCritical(arr, pa, 0, TRACE_JNI_CALL);

test/hotspot/jtreg/vmTestbase/nsk/share/gc/lock/jni/ByteArrayCriticalLocker.cpp

@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2007, 2019, Oracle and/or its affiliates. All rights reserved.
+ * Copyright (c) 2007, 2020, Oracle and/or its affiliates. All rights reserved.
  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
  *
  * This code is free software; you can redistribute it and/or modify it
@@ -55,13 +55,15 @@ JNIEXPORT jbyte JNICALL Java_nsk_share_gc_lock_jni_ByteArrayCriticalLocker_criti
   start_time = time(NULL);
   enterTime /= 1000;
   current_time = 0;
-        while (current_time - start_time < enterTime) {
+  while (difftime(current_time, start_time) < enterTime) {
+    hash = 0;
     pa = (jbyte*) ec_jni->GetPrimitiveArrayCritical(arr, NULL, TRACE_JNI_CALL);
     if (pa != NULL) {
-                        for (i = 0; i < size; ++i)
+      for (i = 0; i < size; ++i) {
         hash ^= pa[i];
+      }
     } else {
-                        hash = 0;
+      jni_env->FatalError("GetPrimitiveArrayCritical returned NULL");
     }
     mssleep((long) sleepTime);
     ec_jni->ReleasePrimitiveArrayCritical(arr, pa, 0, TRACE_JNI_CALL);

test/hotspot/jtreg/vmTestbase/nsk/share/gc/lock/jni/CharArrayCriticalLocker.cpp

@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2007, 2019, Oracle and/or its affiliates. All rights reserved.
+ * Copyright (c) 2007, 2020, Oracle and/or its affiliates. All rights reserved.
  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
  *
  * This code is free software; you can redistribute it and/or modify it
@@ -56,13 +56,15 @@ JNIEXPORT jchar JNICALL Java_nsk_share_gc_lock_jni_CharArrayCriticalLocker_criti
   start_time = time(NULL);
   current_time = 0;
   enterTime /= 1000;
-        while (current_time - start_time < enterTime) {
+  while (difftime(current_time, start_time) < enterTime) {
+    hash = 0;
     pa = (jchar*) ec_jni->GetPrimitiveArrayCritical(arr, NULL, TRACE_JNI_CALL);
     if (pa != NULL) {
-                        for (i = 0; i < size; ++i)
+      for (i = 0; i < size; ++i) {
         hash ^= pa[i];
+      }
     } else {
-                        hash = 0;
+      jni_env->FatalError("GetPrimitiveArrayCritical returned NULL");
     }
     mssleep((long) sleepTime);
     ec_jni->ReleasePrimitiveArrayCritical(arr, pa, 0, TRACE_JNI_CALL);

test/hotspot/jtreg/vmTestbase/nsk/share/gc/lock/jni/DoubleArrayCriticalLocker.cpp

@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2007, 2019, Oracle and/or its affiliates. All rights reserved.
+ * Copyright (c) 2007, 2020, Oracle and/or its affiliates. All rights reserved.
  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
  *
  * This code is free software; you can redistribute it and/or modify it
@@ -56,13 +56,15 @@ JNIEXPORT jdouble JNICALL Java_nsk_share_gc_lock_jni_DoubleArrayCriticalLocker_c
   start_time = time(NULL);
   enterTime /= 1000;
   current_time = 0;
-        while (current_time - start_time < enterTime) {
+  while (difftime(current_time, start_time) < enterTime) {
+    hash = 0;
     pa = (jdouble*) ec_jni->GetPrimitiveArrayCritical(arr, NULL, TRACE_JNI_CALL);
     if (pa != NULL) {
-                        for (i = 0; i < size; ++i)
+      for (i = 0; i < size; ++i) {
         hash += pa[i];
+      }
     } else {
-                        hash = 0;
+      jni_env->FatalError("GetPrimitiveArrayCritical returned NULL");
     }
     mssleep((long) sleepTime);
     ec_jni->ReleasePrimitiveArrayCritical(arr, pa, 0, TRACE_JNI_CALL);

test/hotspot/jtreg/vmTestbase/nsk/share/gc/lock/jni/FloatArrayCriticalLocker.cpp

@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2007, 2019, Oracle and/or its affiliates. All rights reserved.
+ * Copyright (c) 2007, 2020, Oracle and/or its affiliates. All rights reserved.
  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
  *
  * This code is free software; you can redistribute it and/or modify it
@@ -56,13 +56,15 @@ JNIEXPORT jfloat JNICALL Java_nsk_share_gc_lock_jni_FloatArrayCriticalLocker_cri
   start_time = time(NULL);
   enterTime /= 1000;
   current_time = 0;
-        while (current_time - start_time < enterTime) {
+  while (difftime(current_time, start_time) < enterTime) {
+    hash = 0;
     pa = (jfloat*) ec_jni->GetPrimitiveArrayCritical(arr, NULL, TRACE_JNI_CALL);
     if (pa != NULL) {
-                        for (i = 0; i < size; ++i)
+      for (i = 0; i < size; ++i) {
         hash += pa[i];
+      }
     } else {
-                        hash = 0;
+      jni_env->FatalError("GetPrimitiveArrayCritical returned NULL");
     }
     mssleep((long) sleepTime);
     ec_jni->ReleasePrimitiveArrayCritical(arr, pa, 0, TRACE_JNI_CALL);

test/hotspot/jtreg/vmTestbase/nsk/share/gc/lock/jni/IntArrayCriticalLocker.cpp

@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2007, 2019, Oracle and/or its affiliates. All rights reserved.
+ * Copyright (c) 2007, 2020, Oracle and/or its affiliates. All rights reserved.
  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
  *
  * This code is free software; you can redistribute it and/or modify it
@@ -56,13 +56,15 @@ JNIEXPORT jint JNICALL Java_nsk_share_gc_lock_jni_IntArrayCriticalLocker_critica
   start_time = time(NULL);
   enterTime /= 1000;
   current_time = 0;
-        while (current_time - start_time < enterTime) {
+  while (difftime(current_time, start_time) < enterTime) {
+    hash = 0;
     pa = (jint*) ec_jni->GetPrimitiveArrayCritical(arr, NULL, TRACE_JNI_CALL);
     if (pa != NULL) {
-                        for (i = 0; i < size; ++i)
+      for (i = 0; i < size; ++i) {
         hash ^= pa[i];
+      }
     } else {
-                        hash = 0;
+      jni_env->FatalError("GetPrimitiveArrayCritical returned NULL");
     }
     mssleep((long) sleepTime);
     ec_jni->ReleasePrimitiveArrayCritical(arr, pa, 0, TRACE_JNI_CALL);

test/hotspot/jtreg/vmTestbase/nsk/share/gc/lock/jni/LongArrayCriticalLocker.cpp

@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2007, 2019, Oracle and/or its affiliates. All rights reserved.
+ * Copyright (c) 2007, 2020, Oracle and/or its affiliates. All rights reserved.
  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
  *
  * This code is free software; you can redistribute it and/or modify it
@@ -56,13 +56,15 @@ JNIEXPORT jlong JNICALL Java_nsk_share_gc_lock_jni_LongArrayCriticalLocker_criti
   start_time = time(NULL);
   enterTime /= 1000;
   current_time = 0;
-        while (current_time - start_time < enterTime) {
+  while (difftime(current_time, start_time) < enterTime) {
+    hash = 0;
     pa = (jlong*) ec_jni->GetPrimitiveArrayCritical(arr, NULL, TRACE_JNI_CALL);
     if (pa != NULL) {
-                        for (i = 0; i < size; ++i)
+      for (i = 0; i < size; ++i) {
         hash ^= pa[i];
+      }
     } else {
-                        hash = 0;
+      jni_env->FatalError("GetPrimitiveArrayCritical returned NULL");
     }
     mssleep((long) sleepTime);
     ec_jni->ReleasePrimitiveArrayCritical(arr, pa, 0, TRACE_JNI_CALL);

test/hotspot/jtreg/vmTestbase/nsk/share/gc/lock/jni/ShortArrayCriticalLocker.cpp

@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2007, 2019, Oracle and/or its affiliates. All rights reserved.
+ * Copyright (c) 2007, 2020, Oracle and/or its affiliates. All rights reserved.
  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
  *
  * This code is free software; you can redistribute it and/or modify it
@@ -57,12 +57,14 @@ JNIEXPORT jshort JNICALL Java_nsk_share_gc_lock_jni_ShortArrayCriticalLocker_cri
   enterTime /= 1000;
   current_time = 0;
   while (current_time - start_time < enterTime) {
+    hash = 0;
     pa = (jshort*) ec_jni->GetPrimitiveArrayCritical(arr, NULL, TRACE_JNI_CALL);
     if (pa != NULL) {
-                        for (i = 0; i < size; ++i)
+      for (i = 0; i < size; ++i) {
         hash ^= pa[i];
+      }
     } else {
-                        hash = 0;
+      jni_env->FatalError("GetPrimitiveArrayCritical returned NULL");
     }
     mssleep((long) sleepTime);
     ec_jni->ReleasePrimitiveArrayCritical(arr, pa, 0, TRACE_JNI_CALL);

test/hotspot/jtreg/vmTestbase/nsk/share/gc/lock/jni/StringCriticalLocker.cpp

@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2007, 2019, Oracle and/or its affiliates. All rights reserved.
+ * Copyright (c) 2007, 2020, Oracle and/or its affiliates. All rights reserved.
  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
  *
  * This code is free software; you can redistribute it and/or modify it
@@ -57,12 +57,14 @@ JNIEXPORT jchar JNICALL Java_nsk_share_gc_lock_jni_StringCriticalLocker_critical
   enterTime /= 1000;
   current_time = 0;
   while (current_time - start_time < enterTime) {
+    hash = 0;
     pa = ec_jni->GetStringCritical(str, NULL, TRACE_JNI_CALL);
     if (pa != NULL) {
-                        for (i = 0; i < size; ++i)
+      for (i = 0; i < size; ++i) {
         hash ^= pa[i];
+      }
     } else {
-                        hash = JNI_FALSE;
+      jni_env->FatalError("GetStringCritical returned NULL");
     }
     mssleep((long) sleepTime);
     ec_jni->ReleaseStringCritical(str, pa, TRACE_JNI_CALL);

test/jdk/java/security/SecureRandom/DefaultAlgo.java

@@ -26,13 +26,12 @@ import java.security.Provider;
 import java.security.Security;
 import java.security.SecureRandom;
 import java.security.Provider.Service;
-import java.util.Objects;
 import java.util.Arrays;
 import sun.security.provider.SunEntries;
 
 /**
  * @test
- * @bug 8228613 8246613
+ * @bug 8228613 8246613 8248505
  * @summary Ensure that the default SecureRandom algo used is based
  *     on the registration ordering, and falls to next provider
  *     if none are found
@@ -40,6 +39,9 @@ import sun.security.provider.SunEntries;
  */
 public class DefaultAlgo {
 
+    private static final String SR_IMPLCLASS =
+            "sun.security.provider.SecureRandom";
+
     public static void main(String[] args) throws Exception {
         String[] algos = { "A", "B", "C" };
         test3rdParty(algos);
@@ -51,7 +53,8 @@ public class DefaultAlgo {
     private static void test3rdParty(String[] algos) {
         Provider[] provs = {
             new SampleLegacyProvider(algos),
-            new SampleServiceProvider(algos)
+            new SampleServiceProvider(algos),
+            new CustomProvider(algos)
         };
         for (Provider p : provs) {
             checkDefault(p, algos);
@@ -72,9 +75,10 @@ public class DefaultAlgo {
     }
 
     private static void checkDefault(Provider p, String ... algos) {
-        out.println(p.getName() + " with " + Arrays.toString(algos));
-        int pos = Security.insertProviderAt(p, 1);
         String pName = p.getName();
+        out.println(pName + " with " + Arrays.toString(algos));
+        int pos = Security.insertProviderAt(p, 1);
+
         boolean isLegacy = pName.equals("SampleLegacy");
         try {
             if (isLegacy) {
@@ -91,7 +95,13 @@ public class DefaultAlgo {
             out.println("=> Test Passed");
         } finally {
             if (pos != -1) {
-                Security.removeProvider(p.getName());
+                Security.removeProvider(pName);
+            }
+            if (isLegacy) {
+                // add back the removed algos
+                for (String s : algos) {
+                    p.put("SecureRandom." + s, SR_IMPLCLASS);
+                }
             }
         }
     }
@@ -100,7 +110,7 @@ public class DefaultAlgo {
         SampleLegacyProvider(String[] listOfSupportedRNGs) {
             super("SampleLegacy", "1.0", "test provider using legacy put");
             for (String s : listOfSupportedRNGs) {
-                put("SecureRandom." + s, "sun.security.provider.SecureRandom");
+                put("SecureRandom." + s, SR_IMPLCLASS);
             }
         }
     }
@@ -110,8 +120,37 @@ public class DefaultAlgo {
             super("SampleService", "1.0", "test provider using putService");
             for (String s : listOfSupportedRNGs) {
                 putService(new Provider.Service(this, "SecureRandom", s,
-                        "sun.security.provider.SecureRandom", null, null));
+                        SR_IMPLCLASS, null, null));
             }
         }
     }
+
+    // custom provider which overrides putService(...)/getService() and uses
+    // its own Service impl
+    private static class CustomProvider extends Provider {
+        private static class CustomService extends Provider.Service {
+            CustomService(Provider p, String type, String algo, String cName) {
+                super(p, type, algo, cName, null, null);
+            }
+        }
+
+        CustomProvider(String[] listOfSupportedRNGs) {
+            super("Custom", "1.0", "test provider overrides putService with " +
+                    " custom service with legacy registration");
+            for (String s : listOfSupportedRNGs) {
+                putService(new CustomService(this, "SecureRandom", s ,
+                        SR_IMPLCLASS));
+            }
+        }
+        @Override
+        protected void putService(Provider.Service s) {
+            // convert to legacy puts
+            put(s.getType() + "." + s.getAlgorithm(), s.getClassName());
+            put(s.getType() + ":" + s.getAlgorithm(), s);
+        }
+        @Override
+        public Provider.Service getService(String type, String algo) {
+            return (Provider.Service) get(type + ":" + algo);
+        }
+    }
 }

test/jdk/jdk/jfr/event/runtime/TestThreadStartEndEvents.java

@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2013, 2018, Oracle and/or its affiliates. All rights reserved.
+ * Copyright (c) 2013, 2020, Oracle and/or its affiliates. All rights reserved.
  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
  *
  * This code is free software; you can redistribute it and/or modify it
@@ -48,16 +48,19 @@ import jdk.test.lib.jfr.Events;
  */
 
 /**
- * Starts and stops a number of threads in order.
+ * Starts a number of threads in order and verifies
- * Verifies that events are in the same order.
+ * that Thread Start events are in that same order.
+ * The order of Thread End events is non-deterministic.
  */
 public class TestThreadStartEndEvents {
     private final static String EVENT_NAME_THREAD_START = EventNames.ThreadStart;
     private final static String EVENT_NAME_THREAD_END = EventNames.ThreadEnd;
     private static final String THREAD_NAME_PREFIX = "TestThread-";
+    private static int currentThreadIndex = 0;
+    private static int numberOfThreadStartEvents = 0;
+    private static int numberOfThreadEndEvents = 0;
 
     public static void main(String[] args) throws Throwable {
-        // Test Java Thread Start event
         Recording recording = new Recording();
         recording.enable(EVENT_NAME_THREAD_START).withThreshold(Duration.ofMillis(0));
         recording.enable(EVENT_NAME_THREAD_END).withThreshold(Duration.ofMillis(0));
@@ -65,8 +68,6 @@ public class TestThreadStartEndEvents {
         LatchedThread[] threads = startThreads();
         stopThreads(threads);
         recording.stop();
-
-        int currThreadIndex = 0;
         List<RecordedEvent> events = Events.fromRecording(recording);
         events.sort((e1, e2) -> e1.getStartTime().compareTo(e2.getStartTime()));
         Events.hasEvents(events);
@@ -75,22 +76,37 @@ public class TestThreadStartEndEvents {
                 continue;
             }
             System.out.println("Event:" + event);
-            // Threads should be started and stopped in the correct order.
+            String eventType = event.getEventType().getName();
-            Events.assertEventThread(event, threads[currThreadIndex % threads.length]);
+            switch (eventType) {
-            String eventName = currThreadIndex < threads.length ? EVENT_NAME_THREAD_START : EVENT_NAME_THREAD_END;
+                case EVENT_NAME_THREAD_START:
-            if (!eventName.equals(event.getEventType().getName())) {
+                    validateThreadStartEvent(event, threads);
-                throw new Exception("Expected event of type " + eventName + " but got " + event.getEventType().getName());
+                break;
+                case EVENT_NAME_THREAD_END:
+                    validateThreadEndEvent(event);
+                break;
+                default:
+                   throw new RuntimeException("Test encountered an invalid event: " + eventType);
+            }
+        }
+        assertEQ(numberOfThreadStartEvents, threads.length);
+        assertEQ(numberOfThreadEndEvents, threads.length);
     }
 
-            if (eventName == EVENT_NAME_THREAD_START) {
+    // The order of Thread Start events should corresponding to their start order.
+    private static void validateThreadStartEvent(RecordedEvent event, LatchedThread[] threads) {
+        Events.assertEventThread(event, threads[currentThreadIndex++]);
         Events.assertEventThread(event, "parentThread", Thread.currentThread());
         RecordedStackTrace stackTrace = event.getValue("stackTrace");
         assertNotNull(stackTrace);
         RecordedMethod topMethod = stackTrace.getFrames().get(0).getMethod();
         assertEQ(topMethod.getName(), "startThread");
+        numberOfThreadStartEvents++;
     }
-            currThreadIndex++;
+
-        }
+    // The order of Thread End events is non-deterministic. This is because the event
+    // is committed as part of dismantling the JavaThread in the VM, post thread.isAlive().
+    private static void validateThreadEndEvent(RecordedEvent event) {
+        numberOfThreadEndEvents++;
     }
 
     private static LatchedThread[] startThreads() {
@@ -147,5 +163,4 @@ public class TestThreadStartEndEvents {
             stop.countDown();
         }
     }
-
 }