7114376: Make system dictionary hashtable bucket array size configurable

Summary: 7u4 new experimental flag -XX:PredictedClassLoadedCount=#
Reviewed-by: dholmes, phh, dcubed

agent/src/share/classes/sun/jvm/hotspot/memory/LoaderConstraintTable.java

 /*
- * Copyright (c) 2003, Oracle and/or its affiliates. All rights reserved.
+ * Copyright (c) 2003, 2012 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
@@ -42,15 +42,6 @@ public class LoaderConstraintTable extends TwoOopHashtable {
 
   private static synchronized void initialize(TypeDataBase db) {
     Type type = db.lookupType("LoaderConstraintTable");
-    nofBuckets = db.lookupIntConstant("LoaderConstraintTable::_nof_buckets").intValue();
-  }
-
-  // Fields
-  private static int nofBuckets;
-
-  // Accessors
-  public static int getNumOfBuckets() {
-    return nofBuckets;
   }
 
   public LoaderConstraintTable(Address addr) {

agent/src/share/classes/sun/jvm/hotspot/memory/SystemDictionary.java

 /*
- * Copyright (c) 2001, 2010, Oracle and/or its affiliates. All rights reserved.
+ * Copyright (c) 2001, 2012, 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
@@ -36,7 +36,6 @@ public class SystemDictionary {
   private static AddressField placeholdersField;
   private static AddressField loaderConstraintTableField;
   private static sun.jvm.hotspot.types.OopField javaSystemLoaderField;
-  private static int nofBuckets;
 
   private static sun.jvm.hotspot.types.OopField objectKlassField;
   private static sun.jvm.hotspot.types.OopField classLoaderKlassField;
@@ -62,7 +61,6 @@ public class SystemDictionary {
     placeholdersField = type.getAddressField("_placeholders");
     loaderConstraintTableField = type.getAddressField("_loader_constraints");
     javaSystemLoaderField = type.getOopField("_java_system_loader");
-    nofBuckets = db.lookupIntConstant("SystemDictionary::_nof_buckets").intValue();
 
     objectKlassField = type.getOopField(WK_KLASS("Object_klass"));
     classLoaderKlassField = type.getOopField(WK_KLASS("ClassLoader_klass"));
@@ -142,10 +140,6 @@ public class SystemDictionary {
     return newOop(javaSystemLoaderField.getValue());
   }
 
-  public static int getNumOfBuckets() {
-    return nofBuckets;
-  }
-
   private static Oop newOop(OopHandle handle) {
     return VM.getVM().getObjectHeap().newOop(handle);
   }

src/share/vm/classfile/dictionary.cpp

 /*
- * Copyright (c) 2003, 2011, Oracle and/or its affiliates. All rights reserved.
+ * Copyright (c) 2003, 2012, 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
@@ -618,7 +618,8 @@ void Dictionary::print() {
   ResourceMark rm;
   HandleMark   hm;
 
-  tty->print_cr("Java system dictionary (classes=%d)", number_of_entries());
+  tty->print_cr("Java system dictionary (table_size=%d, classes=%d)",
+                 table_size(), number_of_entries());
   tty->print_cr("^ indicates that initiating loader is different from "
                 "defining loader");
 

src/share/vm/classfile/systemDictionary.cpp

 /*
- * Copyright (c) 1997, 2011, Oracle and/or its affiliates. All rights reserved.
+ * Copyright (c) 1997, 2012, 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
@@ -64,6 +64,9 @@ SymbolPropertyTable*   SystemDictionary::_invoke_method_table = NULL;
 
 
 int         SystemDictionary::_number_of_modifications = 0;
+int         SystemDictionary::_sdgeneration               = 0;
+const int   SystemDictionary::_primelist[_prime_array_size] = {1009,2017,4049,5051,10103,
+              20201,40423,99991};
 
 oop         SystemDictionary::_system_loader_lock_obj     =  NULL;
 
@@ -1178,8 +1181,8 @@ void SystemDictionary::set_shared_dictionary(HashtableBucket* t, int length,
 
 klassOop SystemDictionary::find_shared_class(Symbol* class_name) {
   if (shared_dictionary() != NULL) {
-    unsigned int d_hash = dictionary()->compute_hash(class_name, Handle());
-    int d_index = dictionary()->hash_to_index(d_hash);
+    unsigned int d_hash = shared_dictionary()->compute_hash(class_name, Handle());
+    int d_index = shared_dictionary()->hash_to_index(d_hash);
     return shared_dictionary()->find_shared_class(d_index, d_hash, class_name);
   } else {
     return NULL;
@@ -1750,7 +1753,21 @@ void SystemDictionary::placeholders_do(OopClosure* blk) {
   placeholders()->oops_do(blk);
 }
 
-
+// Calculate a "good" systemdictionary size based
+// on predicted or current loaded classes count
+int SystemDictionary::calculate_systemdictionary_size(int classcount) {
+  int newsize = _old_default_sdsize;
+  if ((classcount > 0)  && !DumpSharedSpaces) {
+    int desiredsize = classcount/_average_depth_goal;
+    for (newsize = _primelist[_sdgeneration]; _sdgeneration < _prime_array_size -1;
+         newsize = _primelist[++_sdgeneration]) {
+      if (desiredsize <=  newsize) {
+        break;
+      }
+    }
+  }
+  return newsize;
+}
 bool SystemDictionary::do_unloading(BoolObjectClosure* is_alive) {
   bool result = dictionary()->do_unloading(is_alive);
   constraints()->purge_loader_constraints(is_alive);
@@ -1873,7 +1890,8 @@ void SystemDictionary::initialize(TRAPS) {
   // Allocate arrays
   assert(dictionary() == NULL,
          "SystemDictionary should only be initialized once");
-  _dictionary          = new Dictionary(_nof_buckets);
+  _sdgeneration        = 0;
+  _dictionary          = new Dictionary(calculate_systemdictionary_size(PredictedLoadedClassCount));
   _placeholders        = new PlaceholderTable(_nof_buckets);
   _number_of_modifications = 0;
   _loader_constraints  = new LoaderConstraintTable(_loader_constraint_size);

src/share/vm/classfile/systemDictionary.hpp

 /*
- * Copyright (c) 1997, 2011, Oracle and/or its affiliates. All rights reserved.
+ * Copyright (c) 1997, 2012, 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
@@ -346,6 +346,8 @@ public:
   // loaders.  Returns "true" iff something was unloaded.
   static bool do_unloading(BoolObjectClosure* is_alive);
 
+  static int calculate_systemdictionary_size(int loadedclasses);
+
   // Applies "f->do_oop" to all root oops in the system dictionary.
   static void oops_do(OopClosure* f);
 
@@ -538,12 +540,20 @@ public:
     _loader_constraint_size = 107,                     // number of entries in constraint table
     _resolution_error_size  = 107,                     // number of entries in resolution error table
     _invoke_method_size     = 139,                     // number of entries in invoke method table
-    _nof_buckets            = 1009                     // number of buckets in hash table
+    _nof_buckets            = 1009,                    // number of buckets in hash table for placeholders
+    _old_default_sdsize     = 1009,                    // backward compat for system dictionary size
+    _prime_array_size       = 8,                       // array of primes for system dictionary size
+    _average_depth_goal     = 3                        // goal for lookup length
   };
 
 
   // Static variables
 
+  // hashtable sizes for system dictionary to allow growth
+  // prime numbers for system dictionary size
+  static int                     _sdgeneration;
+  static const int               _primelist[_prime_array_size];
+
   // Hashtable holding loaded classes.
   static Dictionary*            _dictionary;
 

src/share/vm/runtime/globals.hpp

@@ -1042,6 +1042,9 @@ class CommandLineFlags {
   notproduct(bool, PrintSystemDictionaryAtExit, false,                      \
           "Prints the system dictionary at exit")                           \
                                                                             \
+  experimental(intx, PredictedLoadedClassCount, 0,                          \
+          "Experimental: Tune loaded class cache starting size.")           \
+                                                                            \
   diagnostic(bool, UnsyncloadClass, false,                                  \
           "Unstable: VM calls loadClass unsynchronized. Custom "            \
           "class loader  must call VM synchronized for findClass "          \

src/share/vm/runtime/vmStructs.cpp

 /*
- * Copyright (c) 2000, 2011, Oracle and/or its affiliates. All rights reserved.
+ * Copyright (c) 2000, 2012, 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
@@ -2261,13 +2261,6 @@ static inline uint64_t cast_uint64_t(size_t x)
                                                                           \
   declare_constant(SymbolTable::symbol_table_size)                        \
                                                                           \
-  /********************/                                                  \
-  /* SystemDictionary */                                                  \
-  /********************/                                                  \
-                                                                          \
-  declare_constant(SystemDictionary::_loader_constraint_size)             \
-  declare_constant(SystemDictionary::_nof_buckets)                        \
-                                                                          \
   /***********************************/                                   \
   /* LoaderConstraintTable constants */                                   \
   /***********************************/                                   \

src/share/vm/utilities/hashtable.hpp

 /*
- * Copyright (c) 2003, 2011, Oracle and/or its affiliates. All rights reserved.
+ * Copyright (c) 2003, 2012, 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
@@ -183,7 +183,6 @@ protected:
 
   // Accessor
   int entry_size() const { return _entry_size; }
-  int table_size() { return _table_size; }
 
   // The following method is MT-safe and may be used with caution.
   BasicHashtableEntry* bucket(int i);
@@ -195,6 +194,7 @@ protected:
   BasicHashtableEntry* new_entry(unsigned int hashValue);
 
 public:
+  int table_size() { return _table_size; }
   void set_entry(int index, BasicHashtableEntry* entry);
 
   void add_entry(int index, BasicHashtableEntry* entry);