8261607: SA attach is exceeding JNI Local Refs capacity

Reviewed-by: sgehwolf, amenkov

Author: plummercj

src/jdk.hotspot.agent/linux/native/libsaproc/LinuxDebuggerLocal.cpp

@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2002, 2020, Oracle and/or its affiliates. All rights reserved.
+ * Copyright (c) 2002, 2021, Oracle and/or its affiliates. All rights reserved.
  * Copyright (c) 2019, 2020, NTT DATA.
  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
  *
@@ -183,6 +183,8 @@ static void fillThreadsAndLoadObjects(JNIEnv* env, jobject this_obj, struct ps_p
     CHECK_EXCEPTION;
     env->CallBooleanMethod(threadList, listAdd_ID, thread);
     CHECK_EXCEPTION;
+    env->DeleteLocalRef(thread);
+    env->DeleteLocalRef(threadList);
   }
 
   // add load objects
@@ -205,6 +207,9 @@ static void fillThreadsAndLoadObjects(JNIEnv* env, jobject this_obj, struct ps_p
      CHECK_EXCEPTION;
      env->CallBooleanMethod(loadObjectList, listAdd_ID, loadObject);
      CHECK_EXCEPTION;
+     env->DeleteLocalRef(str);
+     env->DeleteLocalRef(loadObject);
+     env->DeleteLocalRef(loadObjectList);
   }
 }
 

src/jdk.hotspot.agent/macosx/native/libsaproc/MacosxDebuggerLocal.m

@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2002, 2020, Oracle and/or its affiliates. All rights reserved.
+ * Copyright (c) 2002, 2021, 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
@@ -965,14 +965,17 @@ static bool wait_for_exception() {
     called from Java_sun_jvm_hotspot_debugger_bsd_BsdDebuggerLocal_attach0__Ljava_lang_String_2Ljava_lang_String_2 */
 static void fillLoadObjects(JNIEnv* env, jobject this_obj, struct ps_prochandle* ph) {
   int n = 0, i = 0;
+  jobject loadObjectList;
+
+  loadObjectList = (*env)->GetObjectField(env, this_obj, loadObjectList_ID);
+  CHECK_EXCEPTION;
 
   // add load objects
   n = get_num_libs(ph);
   for (i = 0; i < n; i++) {
      uintptr_t base;
      const char* name;
      jobject loadObject;
-     jobject loadObjectList;
      jstring nameString;
 
      base = get_lib_base(ph, i);
@@ -982,10 +985,10 @@ static void fillLoadObjects(JNIEnv* env, jobject this_obj, struct ps_prochandle*
      loadObject = (*env)->CallObjectMethod(env, this_obj, createLoadObject_ID,
                                             nameString, (jlong)0, (jlong)base);
      CHECK_EXCEPTION;
-     loadObjectList = (*env)->GetObjectField(env, this_obj, loadObjectList_ID);
-     CHECK_EXCEPTION;
      (*env)->CallBooleanMethod(env, loadObjectList, listAdd_ID, loadObject);
      CHECK_EXCEPTION;
+     (*env)->DeleteLocalRef(env, nameString);
+     (*env)->DeleteLocalRef(env, loadObject);
   }
 }
 

src/jdk.hotspot.agent/windows/native/libsaproc/sawindbg.cpp

@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2002, 2020, Oracle and/or its affiliates. All rights reserved.
+ * Copyright (c) 2002, 2021, 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
@@ -503,6 +503,7 @@ static bool addLoadObjects(JNIEnv* env, jobject obj) {
     env->CallVoidMethod(obj, addLoadObject_ID, strName, (jlong) params[u].Size,
                         (jlong) params[u].Base);
     CHECK_EXCEPTION_(false);
+    env->DeleteLocalRef(strName);
   }
 
   return true;
@@ -629,6 +630,7 @@ static bool addThreads(JNIEnv* env, jobject obj) {
 
     env->CallVoidMethod(obj, setThreadIntegerRegisterSet_ID, (jlong)ptrThreadIds[t], regs);
     CHECK_EXCEPTION_(false);
+    env->DeleteLocalRef(regs);
 
     ULONG sysId;
     COM_VERIFY_OK_(ptrIDebugSystemObjects->GetCurrentThreadSystemId(&sysId),

test/hotspot/jtreg/serviceability/sa/ClhsdbLauncher.java

@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2017, 2020, Oracle and/or its affiliates. All rights reserved.
+ * Copyright (c) 2017, 2021, 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
@@ -144,6 +144,9 @@ private String runCmd(List<String> commands,
         System.out.println("Output: ");
         System.out.println(output);
 
+        // -Xcheck:jni might be set via TEST_VM_OPTS. Make sure there are no warnings.
+        oa.shouldNotMatch("^WARNING: JNI local refs:.*$");
+        oa.shouldNotMatch("^WARNING in native method:.*$");
         // This will detect most SA failures, including during the attach.
         oa.shouldNotMatch("^sun.jvm.hotspot.debugger.DebuggerException:.*$");
         // This will detect unexpected exceptions, like NPEs and asserts, that are caught