8220774: Add HandshakeALot diag option

Reviewed-by: dcubed, dholmes

src/hotspot/share/runtime/globals.hpp

@@ -371,6 +371,10 @@ define_pd_global(uint64_t,MaxRAM,                    1ULL*G);
           "Generate a lot of safepoints. This works with "                  \
           "GuaranteedSafepointInterval")                                    \
                                                                             \
+  diagnostic(bool, HandshakeALot, false,                                    \
+          "Generate a lot of handshakes. This works with "                  \
+          "GuaranteedSafepointInterval")                                    \
+                                                                            \
   product_pd(bool, BackgroundCompilation,                                   \
           "A thread requesting compilation is not blocked during "          \
           "compilation")                                                    \

src/hotspot/share/runtime/thread.cpp

@@ -2928,9 +2928,21 @@ void JavaThread::oops_do(OopClosure* f, CodeBlobClosure* cf) {
   }
 }
 
+#ifdef ASSERT
+void JavaThread::verify_states_for_handshake() {
+  // This checks that the thread has a correct frame state during a handshake.
+  assert((!has_last_Java_frame() && java_call_counter() == 0) ||
+         (has_last_Java_frame() && java_call_counter() > 0),
+         "unexpected frame info: has_last_frame=%d, java_call_counter=%d",
+         has_last_Java_frame(), java_call_counter());
+}
+#endif
+
 void JavaThread::nmethods_do(CodeBlobClosure* cf) {
   assert((!has_last_Java_frame() && java_call_counter() == 0) ||
-         (has_last_Java_frame() && java_call_counter() > 0), "wrong java_sp info!");
+         (has_last_Java_frame() && java_call_counter() > 0),
+         "unexpected frame info: has_last_frame=%d, java_call_counter=%d",
+         has_last_Java_frame(), java_call_counter());
 
   if (has_last_Java_frame()) {
     // Traverse the execution stack

src/hotspot/share/runtime/thread.hpp

@@ -1874,6 +1874,9 @@ class JavaThread: public Thread {
   // RedefineClasses Support
   void metadata_do(MetadataClosure* f);
 
+  // Debug method asserting thread states are correct during a handshake operation.
+  DEBUG_ONLY(void verify_states_for_handshake();)
+
   // Misc. operations
   char* name() const { return (char*)get_thread_name(); }
   void print_on(outputStream* st, bool print_extended_info) const;

src/hotspot/share/runtime/vmThread.cpp

@@ -434,22 +434,35 @@ void VMThread::evaluate_operation(VM_Operation* op) {
 static VM_None    safepointALot_op("SafepointALot");
 static VM_Cleanup cleanup_op;
 
-VM_Operation* VMThread::no_op_safepoint(bool check_time) {
+class HandshakeALotTC : public ThreadClosure {
+ public:
+  virtual void do_thread(Thread* thread) {
+#ifdef ASSERT
+    assert(thread->is_Java_thread(), "must be");
+    JavaThread* jt = (JavaThread*)thread;
+    jt->verify_states_for_handshake();
+#endif
+  }
+};
+
+VM_Operation* VMThread::no_op_safepoint() {
+  // Check for handshakes first since we may need to return a VMop.
+  if (HandshakeALot) {
+    HandshakeALotTC haltc;
+    Handshake::execute(&haltc);
+  }
+  // Check for a cleanup before SafepointALot to keep stats correct.
+  long interval_ms = SafepointTracing::time_since_last_safepoint_ms();
+  bool max_time_exceeded = GuaranteedSafepointInterval != 0 &&
+                           (interval_ms >= GuaranteedSafepointInterval);
+  if (max_time_exceeded && SafepointSynchronize::is_cleanup_needed()) {
+    return &cleanup_op;
+  }
   if (SafepointALot) {
     return &safepointALot_op;
   }
-  if (!SafepointSynchronize::is_cleanup_needed()) {
+  // Nothing to be done.
-    return NULL;
+  return NULL;
-  }
-  if (check_time) {
-    long interval_ms = SafepointTracing::time_since_last_safepoint_ms();
-    bool max_time_exceeded = GuaranteedSafepointInterval != 0 &&
-                             (interval_ms > GuaranteedSafepointInterval);
-    if (!max_time_exceeded) {
-      return NULL;
-    }
-  }
-  return &cleanup_op;
 }
 
 void VMThread::loop() {
@@ -491,19 +504,22 @@ void VMThread::loop() {
           exit(-1);
         }
 
-        if (timedout && (_cur_vm_operation = VMThread::no_op_safepoint(false)) != NULL) {
+        if (timedout) {
-          MutexUnlockerEx mul(VMOperationQueue_lock,
+          // Have to unlock VMOperationQueue_lock just in case no_op_safepoint()
-                              Mutex::_no_safepoint_check_flag);
+          // has to do a handshake.
-          // Force a safepoint since we have not had one for at least
+          MutexUnlockerEx mul(VMOperationQueue_lock, Mutex::_no_safepoint_check_flag);
-          // 'GuaranteedSafepointInterval' milliseconds.  This will run all
+          if ((_cur_vm_operation = VMThread::no_op_safepoint()) != NULL) {
-          // the clean-up processing that needs to be done regularly at a
+            // Force a safepoint since we have not had one for at least
-          // safepoint
+            // 'GuaranteedSafepointInterval' milliseconds and we need to clean
-          SafepointSynchronize::begin();
+            // something. This will run all the clean-up processing that needs
-          #ifdef ASSERT
+            // to be done at a safepoint.
+            SafepointSynchronize::begin();
+            #ifdef ASSERT
             if (GCALotAtAllSafepoints) InterfaceSupport::check_gc_alot();
-          #endif
+            #endif
-          SafepointSynchronize::end();
+            SafepointSynchronize::end();
-          _cur_vm_operation = NULL;
+            _cur_vm_operation = NULL;
+          }
         }
         _cur_vm_operation = _vm_queue->remove_next();
 
@@ -615,10 +631,9 @@ void VMThread::loop() {
       VMOperationRequest_lock->notify_all();
     }
 
-    //
+    // We want to make sure that we get to a safepoint regularly
-    // We want to make sure that we get to a safepoint regularly.
+    // even when executing VMops that don't require safepoints.
-    //
+    if ((_cur_vm_operation = VMThread::no_op_safepoint()) != NULL) {
-    if ((_cur_vm_operation = VMThread::no_op_safepoint(false)) != NULL) {
       HandleMark hm(VMThread::vm_thread());
       SafepointSynchronize::begin();
       SafepointSynchronize::end();

src/hotspot/share/runtime/vmThread.hpp

@@ -123,7 +123,7 @@ class VMThread: public NamedThread {
 
   static VMOperationTimeoutTask* _timeout_task;
 
-  static VM_Operation* no_op_safepoint(bool check_time);
+  static VM_Operation* no_op_safepoint();
 
   void evaluate_operation(VM_Operation* op);
 

test/hotspot/jtreg/ProblemList.txt

@@ -80,7 +80,6 @@ gc/metaspace/CompressedClassSpaceSizeInJmapHeap.java 8193639 solaris-all
 
 # :hotspot_runtime
 
-runtime/handshake/HandshakeWalkSuspendExitTest.java 8214174 generic-all
 runtime/NMT/CheckForProperDetailStackTrace.java 8218458 generic-all
 runtime/SharedArchiveFile/SASymbolTableTest.java 8193639 solaris-all
 runtime/containers/docker/TestCPUSets.java 8220672 generic-all

test/hotspot/jtreg/runtime/Thread/SuspendAtExit.java

@@ -26,6 +26,7 @@
  * @bug 8167108
  * @summary Stress test java.lang.Thread.suspend() at thread exit.
  * @run main/othervm -Xlog:thread+smr=debug SuspendAtExit
+ * @run main/othervm -Xlog:thread+smr=debug -XX:+UnlockDiagnosticVMOptions -XX:GuaranteedSafepointInterval=1 -XX:+HandshakeALot SuspendAtExit
  */
 
 import java.util.concurrent.CountDownLatch;

test/hotspot/jtreg/runtime/handshake/HandshakeSuspendExitTest.java

@@ -0,0 +1,104 @@
+/*
+ * Copyright (c) 2019, 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
+ * under the terms of the GNU General Public License version 2 only, as
+ * published by the Free Software Foundation.
+ *
+ * This code is distributed in the hope that it will be useful, but WITHOUT
+ * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
+ * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
+ * version 2 for more details (a copy is included in the LICENSE file that
+ * accompanied this code).
+ *
+ * You should have received a copy of the GNU General Public License version
+ * 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 HandshakeSuspendExitTest
+ * @summary This test tries to stress the handshakes with new and exiting threads while suspending them.
+ * @library /testlibrary /test/lib
+ * @build HandshakeSuspendExitTest
+ * @run main/othervm -XX:+UnlockDiagnosticVMOptions -XX:GuaranteedSafepointInterval=1 -XX:+HandshakeALot HandshakeSuspendExitTest
+ */
+
+public class HandshakeSuspendExitTest  implements Runnable {
+
+    static Thread[] _suspend_threads = new Thread[16];
+    static volatile boolean _exit_now = false;
+    static java.util.concurrent.Semaphore _sem = new java.util.concurrent.Semaphore(0);
+
+    @Override
+    public void run() {
+        _sem.release();
+        while (!_exit_now) {
+            // Leave last 2 threads running.
+            for (int i = 0; i < _suspend_threads.length - 2; i++) {
+                if (Thread.currentThread() != thr) {
+                    thr.suspend();
+                    thr.resume();
+                }
+            }
+        }
+        _sem.release();
+    }
+
+    public static void main(String... args) throws Exception {
+        HandshakeSuspendExitTest test = new HandshakeSuspendExitTest();
+        // Fire-up suspend threads.
+        for (int i = 0; i < _suspend_threads.length; i++) {
+            _suspend_threads[i] = new Thread(test);
+        }
+        for (int i = 0; i < _suspend_threads.length; i++) {
+            _suspend_threads[i].start();
+        }
+        // Wait for all suspend-threads to start looping.
+        for (Thread thr : _suspend_threads) {
+            _sem.acquire();
+        }
+
+        // Fire-up exiting threads.
+        Thread[] exit_threads = new Thread[128];
+        for (int i = 0; i < exit_threads.length; i++) {
+            exit_threads[i] = new Thread();
+            exit_threads[i].start();
+        }
+
+        // Try to suspend them.
+        for (Thread thr : exit_threads) {
+            thr.suspend();
+        }
+        for (Thread thr : exit_threads) {
+            thr.resume();
+        }
+
+        // Start exit and join.
+        _exit_now = true;
+        int waiting = _suspend_threads.length;
+        do {
+            // Resume any worker threads that might have suspended
+            // each other at exactly the same time so they can see
+            // _exit_now and check in via the semaphore.
+            for (Thread thr : _suspend_threads) {
+                thr.resume();
+            }
+            while (_sem.tryAcquire()) {
+                --waiting;
+            }
+        } while (waiting > 0);
+        for (Thread thr : _suspend_threads) {
+            thr.join();
+        }
+        for (Thread thr : exit_threads) {
+            thr.join();
+        }
+    }
+}

test/hotspot/jtreg/runtime/handshake/HandshakeTransitionTest.java

@@ -62,6 +62,7 @@ public class HandshakeTransitionTest {
                     true,
                     "-Djava.library.path=" + lib,
                     "-XX:+SafepointALot",
+                    "-XX:+HandshakeALot",
                     "-XX:GuaranteedSafepointInterval=20",
                     "-Xlog:ergo*",
                     "-XX:ParallelGCThreads=1",

test/hotspot/jtreg/runtime/handshake/HandshakeWalkSuspendExitTest.java

@@ -1,93 +0,0 @@
-/*
- * Copyright (c) 2018, 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
- * under the terms of the GNU General Public License version 2 only, as
- * published by the Free Software Foundation.
- *
- * This code is distributed in the hope that it will be useful, but WITHOUT
- * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
- * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
- * version 2 for more details (a copy is included in the LICENSE file that
- * accompanied this code).
- *
- * You should have received a copy of the GNU General Public License version
- * 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 HandshakeWalkSuspendExitTest
- * @summary This test tries to stress the handshakes with new and exiting threads while suspending them.
- * @library /testlibrary /test/lib
- * @build HandshakeWalkSuspendExitTest
- * @run driver ClassFileInstaller sun.hotspot.WhiteBox
- *                              sun.hotspot.WhiteBox$WhiteBoxPermission
- * @run main/othervm -Xbootclasspath/a:. -XX:+UnlockDiagnosticVMOptions -XX:+WhiteBoxAPI HandshakeWalkSuspendExitTest
- */
-
-import jdk.test.lib.Asserts;
-import sun.hotspot.WhiteBox;
-
-public class HandshakeWalkSuspendExitTest  implements Runnable {
-
-    static final int _test_threads = 8;
-    static final int _test_exit_threads = 128;
-    static Thread[] _threads = new Thread[_test_threads];
-    static volatile boolean exit_now = false;
-    static java.util.concurrent.Semaphore _sem = new java.util.concurrent.Semaphore(0);
-
-    @Override
-    public void run() {
-        WhiteBox wb = WhiteBox.getWhiteBox();
-        while (!exit_now) {
-            _sem.release();
-            // We only suspend threads on even index and not ourself.
-            // Otherwise we can accidentially suspend all threads.
-            for (int i = 0; i < _threads.length; i += 2) {
-                wb.handshakeWalkStack(null /* ignored */, true /* stackwalk all threads */);
-                if (Thread.currentThread() != _threads[i]) {
-                    _threads[i].suspend();
-                    _threads[i].resume();
-                }
-            }
-            for (int i = 0; i < _threads.length; i += 2) {
-                wb.handshakeWalkStack(_threads[i] /* thread to stackwalk */, false /* stackwalk one thread */);
-                if (Thread.currentThread() != _threads[i]) {
-                    _threads[i].suspend();
-                    _threads[i].resume();
-                }
-            }
-        }
-    }
-
-    public static void main(String... args) throws Exception {
-        HandshakeWalkSuspendExitTest test = new HandshakeWalkSuspendExitTest();
-
-        for (int i = 0; i < _threads.length; i++) {
-            _threads[i] = new Thread(test);
-            _threads[i].start();
-        }
-        for (int i = 0; i < _test_threads; i++) {
-            _sem.acquire();
-        }
-        Thread[] exit_threads = new Thread[_test_exit_threads];
-        for (int i = 0; i < _test_exit_threads; i++) {
-            exit_threads[i] = new Thread(new Runnable() { public void run() {} });
-            exit_threads[i].start();
-        }
-        exit_now = true;
-        for (int i = 0; i < _threads.length; i++) {
-            _threads[i].join();
-        }
-        for (int i = 0; i < exit_threads.length; i++) {
-            exit_threads[i].join();
-        }
-    }
-}