8146705: Improve JVMCI support for blocking compilation

Reviewed-by: twisti, never, iveresov

hotspot/src/share/vm/compiler/compileBroker.cpp

@@ -227,6 +227,11 @@ bool compileBroker_init() {
 CompileTaskWrapper::CompileTaskWrapper(CompileTask* task) {
   CompilerThread* thread = CompilerThread::current();
   thread->set_task(task);
+#if INCLUDE_JVMCI
+  if (task->is_blocking() && CompileBroker::compiler(task->comp_level())->is_jvmci()) {
+    task->set_jvmci_compiler_thread(thread);
+  }
+#endif
   CompileLog*     log  = thread->log();
   if (log != NULL)  task->log_task_start(log);
 }
@@ -245,10 +250,12 @@ CompileTaskWrapper::~CompileTaskWrapper() {
       MutexLocker notifier(task->lock(), thread);
       task->mark_complete();
 #if INCLUDE_JVMCI
-      if (CompileBroker::compiler(task->comp_level())->is_jvmci() &&
-        !task->has_waiter()) {
-        // The waiting thread timed out and thus did not free the task.
-        free_task = true;
+      if (CompileBroker::compiler(task->comp_level())->is_jvmci()) {
+        if (!task->has_waiter()) {
+          // The waiting thread timed out and thus did not free the task.
+          free_task = true;
+        }
+        task->set_jvmci_compiler_thread(NULL);
       }
 #endif
       if (!free_task) {
@@ -1332,11 +1339,56 @@ CompileTask* CompileBroker::create_compile_task(CompileQueue*       queue,
   return new_task;
 }
 
-// 1 second should be long enough to complete most JVMCI compilations
-// and not too long to stall a blocking JVMCI compilation that
-// is trying to acquire a lock held by the app thread that submitted the
-// compilation.
-static const long BLOCKING_JVMCI_COMPILATION_TIMEOUT = 1000;
+#if INCLUDE_JVMCI
+// The number of milliseconds to wait before checking if the
+// JVMCI compiler thread is blocked.
+static const long BLOCKING_JVMCI_COMPILATION_WAIT_TIMESLICE = 500;
+
+// The number of successive times the above check is allowed to
+// see a blocked JVMCI compiler thread before unblocking the
+// thread waiting for the compilation to finish.
+static const int BLOCKING_JVMCI_COMPILATION_WAIT_TO_UNBLOCK_ATTEMPTS = 5;
+
+/**
+ * Waits for a JVMCI compiler to complete a given task. This thread
+ * waits until either the task completes or it sees the JVMCI compiler
+ * thread is blocked for N consecutive milliseconds where N is
+ * BLOCKING_JVMCI_COMPILATION_WAIT_TIMESLICE *
+ * BLOCKING_JVMCI_COMPILATION_WAIT_TO_UNBLOCK_ATTEMPTS.
+ *
+ * @return true if this thread needs to free/recycle the task
+ */
+bool CompileBroker::wait_for_jvmci_completion(CompileTask* task, JavaThread* thread) {
+  MutexLocker waiter(task->lock(), thread);
+  int consecutively_blocked = 0;
+  while (task->lock()->wait(!Mutex::_no_safepoint_check_flag, BLOCKING_JVMCI_COMPILATION_WAIT_TIMESLICE)) {
+    CompilerThread* jvmci_compiler_thread = task->jvmci_compiler_thread();
+    if (jvmci_compiler_thread != NULL) {
+      JavaThreadState state;
+      {
+        // A JVMCI compiler thread should not disappear at this point
+        // but let's be extra safe.
+        MutexLocker mu(Threads_lock, thread);
+        state = jvmci_compiler_thread->thread_state();
+      }
+      if (state == _thread_blocked) {
+        if (++consecutively_blocked == BLOCKING_JVMCI_COMPILATION_WAIT_TO_UNBLOCK_ATTEMPTS) {
+          if (PrintCompilation) {
+            task->print(tty, "wait for blocking compilation timed out");
+          }
+          break;
+        }
+      } else {
+        consecutively_blocked = 0;
+      }
+    } else {
+      // Still waiting on JVMCI compiler queue
+    }
+  }
+  task->clear_waiter();
+  return task->is_complete();
+}
+#endif
 
 /**
  *  Wait for the compilation task to complete.
@@ -1356,16 +1408,7 @@ void CompileBroker::wait_for_completion(CompileTask* task) {
   bool free_task;
 #if INCLUDE_JVMCI
   if (compiler(task->comp_level())->is_jvmci()) {
-    MutexLocker waiter(task->lock(), thread);
-    // No need to check if compilation has completed - just
-    // rely on the time out. The JVMCI compiler thread will
-    // recycle the CompileTask.
-    task->lock()->wait(!Mutex::_no_safepoint_check_flag, BLOCKING_JVMCI_COMPILATION_TIMEOUT);
-    // If the compilation completes while has_waiter is true then
-    // this thread is responsible for freeing the task.  Otherwise
-    // the compiler thread will free the task.
-    task->clear_waiter();
-    free_task = task->is_complete();
+    free_task = wait_for_jvmci_completion(task, thread);
   } else
 #endif
   {

hotspot/src/share/vm/compiler/compileBroker.hpp

@@ -233,6 +233,9 @@ class CompileBroker: AllStatic {
                                           const char*         comment,
                                           bool                blocking);
   static void wait_for_completion(CompileTask* task);
+#if INCLUDE_JVMCI
+  static bool wait_for_jvmci_completion(CompileTask* task, JavaThread* thread);
+#endif
 
   static void invoke_compiler_on_method(CompileTask* task);
   static void post_compile(CompilerThread* thread, CompileTask* task, EventCompilation& event, bool success, ciEnv* ci_env);

hotspot/src/share/vm/compiler/compileTask.cpp

@@ -91,6 +91,7 @@ void CompileTask::initialize(int compile_id,
   _osr_bci = osr_bci;
   _is_blocking = is_blocking;
   JVMCI_ONLY(_has_waiter = CompileBroker::compiler(comp_level)->is_jvmci();)
+  JVMCI_ONLY(_jvmci_compiler_thread = NULL;)
   _comp_level = comp_level;
   _num_inlined_bytecodes = 0;
 

hotspot/src/share/vm/compiler/compileTask.hpp

@@ -56,6 +56,8 @@ class CompileTask : public CHeapObj<mtCompiler> {
   bool         _is_blocking;
 #if INCLUDE_JVMCI
   bool         _has_waiter;
+  // Compiler thread for a blocking JVMCI compilation
+  CompilerThread* _jvmci_compiler_thread;
 #endif
   int          _comp_level;
   int          _num_inlined_bytecodes;
@@ -92,6 +94,12 @@ class CompileTask : public CHeapObj<mtCompiler> {
 #if INCLUDE_JVMCI
   bool         has_waiter() const                { return _has_waiter; }
   void         clear_waiter()                    { _has_waiter = false; }
+  CompilerThread* jvmci_compiler_thread() const  { return _jvmci_compiler_thread; }
+  void         set_jvmci_compiler_thread(CompilerThread* t) {
+    assert(is_blocking(), "must be");
+    assert((t == NULL) != (_jvmci_compiler_thread == NULL), "must be");
+    _jvmci_compiler_thread = t;
+  }
 #endif
 
   nmethodLocker* code_handle() const             { return _code_handle; }

hotspot/src/share/vm/runtime/advancedThresholdPolicy.cpp

@@ -165,7 +165,7 @@ bool AdvancedThresholdPolicy::is_method_profiled(Method* method) {
 // Called with the queue locked and with at least one element
 CompileTask* AdvancedThresholdPolicy::select_task(CompileQueue* compile_queue) {
 #if INCLUDE_JVMCI
-  CompileTask *max_non_jvmci_task = NULL;
+  CompileTask *max_blocking_task = NULL;
 #endif
   CompileTask *max_task = NULL;
   Method* max_method = NULL;
@@ -197,13 +197,25 @@ CompileTask* AdvancedThresholdPolicy::select_task(CompileQueue* compile_queue) {
         max_method = method;
       }
     }
+#if INCLUDE_JVMCI
+    if (UseJVMCICompiler && task->is_blocking()) {
+      if (max_blocking_task == NULL || compare_methods(method, max_blocking_task->method())) {
+        max_blocking_task = task;
+      }
+    }
+#endif
     task = next_task;
   }
 
 #if INCLUDE_JVMCI
   if (UseJVMCICompiler) {
-    if (max_non_jvmci_task != NULL) {
-      max_task = max_non_jvmci_task;
+    if (max_blocking_task != NULL) {
+      // In blocking compilation mode, the CompileBroker will make
+      // compilations submitted by a JVMCI compiler thread non-blocking. These
+      // compilations should be scheduled after all blocking compilations
+      // to service non-compiler related compilations sooner and reduce the
+      // chance of such compilations timing out.
+      max_task = max_blocking_task;
       max_method = max_task->method();
     }
   }

hotspot/src/share/vm/runtime/compilationPolicy.cpp

@@ -159,6 +159,26 @@ bool CompilationPolicy::is_compilation_enabled() {
   return !delay_compilation_during_startup() && CompileBroker::should_compile_new_jobs();
 }
 
+CompileTask* CompilationPolicy::select_task_helper(CompileQueue* compile_queue) {
+#if INCLUDE_JVMCI
+  if (UseJVMCICompiler && !BackgroundCompilation) {
+    /*
+     * In blocking compilation mode, the CompileBroker will make
+     * compilations submitted by a JVMCI compiler thread non-blocking. These
+     * compilations should be scheduled after all blocking compilations
+     * to service non-compiler related compilations sooner and reduce the
+     * chance of such compilations timing out.
+     */
+    for (CompileTask* task = compile_queue->first(); task != NULL; task = task->next()) {
+      if (task->is_blocking()) {
+        return task;
+      }
+    }
+  }
+#endif
+  return compile_queue->first();
+}
+
 #ifndef PRODUCT
 void CompilationPolicy::print_time() {
   tty->print_cr ("Accumulated compilationPolicy times:");
@@ -339,7 +359,7 @@ void NonTieredCompPolicy::disable_compilation(Method* method) {
 }
 
 CompileTask* NonTieredCompPolicy::select_task(CompileQueue* compile_queue) {
-  return compile_queue->first();
+  return select_task_helper(compile_queue);
 }
 
 bool NonTieredCompPolicy::is_mature(Method* method) {

hotspot/src/share/vm/runtime/compilationPolicy.hpp

@@ -58,6 +58,8 @@ public:
   static void set_policy(CompilationPolicy* policy) { _policy = policy; }
   static CompilationPolicy* policy()                { return _policy; }
 
+  static CompileTask* select_task_helper(CompileQueue* compile_queue);
+
   // Profiling
   elapsedTimer* accumulated_time() { return &_accumulated_time; }
   void print_time() PRODUCT_RETURN;

hotspot/src/share/vm/runtime/simpleThresholdPolicy.cpp

@@ -168,7 +168,7 @@ void SimpleThresholdPolicy::handle_counter_overflow(Method* method) {
 
 // Called with the queue locked and with at least one element
 CompileTask* SimpleThresholdPolicy::select_task(CompileQueue* compile_queue) {
-  return compile_queue->first();
+  return select_task_helper(compile_queue);
 }
 
 void SimpleThresholdPolicy::reprofile(ScopeDesc* trap_scope, bool is_osr) {