8014262: PrintStringTableStatistics should include more footprint info
Summary: Added info for the string/symbol objects and the hash entries
Reviewed-by: coleenp, rbackman
--- a/hotspot/src/share/vm/classfile/symbolTable.cpp Fri May 17 17:52:07 2013 -0700
+++ b/hotspot/src/share/vm/classfile/symbolTable.cpp Sat May 18 20:41:01 2013 -0700
@@ -35,7 +35,6 @@
#include "oops/oop.inline2.hpp"
#include "runtime/mutexLocker.hpp"
#include "utilities/hashtable.inline.hpp"
-#include "utilities/numberSeq.hpp"
// --------------------------------------------------------------------------
@@ -451,21 +450,7 @@
}
void SymbolTable::dump(outputStream* st) {
- NumberSeq summary;
- for (int i = 0; i < the_table()->table_size(); ++i) {
- int count = 0;
- for (HashtableEntry<Symbol*, mtSymbol>* e = the_table()->bucket(i);
- e != NULL; e = e->next()) {
- count++;
- }
- summary.add((double)count);
- }
- st->print_cr("SymbolTable statistics:");
- st->print_cr("Number of buckets : %7d", summary.num());
- st->print_cr("Average bucket size : %7.0f", summary.avg());
- st->print_cr("Variance of bucket size : %7.0f", summary.variance());
- st->print_cr("Std. dev. of bucket size: %7.0f", summary.sd());
- st->print_cr("Maximum bucket size : %7.0f", summary.maximum());
+ the_table()->dump_table(st, "SymbolTable");
}
@@ -814,21 +799,7 @@
}
void StringTable::dump(outputStream* st) {
- NumberSeq summary;
- for (int i = 0; i < the_table()->table_size(); ++i) {
- HashtableEntry<oop, mtSymbol>* p = the_table()->bucket(i);
- int count = 0;
- for ( ; p != NULL; p = p->next()) {
- count++;
- }
- summary.add((double)count);
- }
- st->print_cr("StringTable statistics:");
- st->print_cr("Number of buckets : %7d", summary.num());
- st->print_cr("Average bucket size : %7.0f", summary.avg());
- st->print_cr("Variance of bucket size : %7.0f", summary.variance());
- st->print_cr("Std. dev. of bucket size: %7.0f", summary.sd());
- st->print_cr("Maximum bucket size : %7.0f", summary.maximum());
+ the_table()->dump_table(st, "StringTable");
}
--- a/hotspot/src/share/vm/utilities/hashtable.cpp Fri May 17 17:52:07 2013 -0700
+++ b/hotspot/src/share/vm/utilities/hashtable.cpp Sat May 18 20:41:01 2013 -0700
@@ -33,6 +33,7 @@
#include "utilities/dtrace.hpp"
#include "utilities/hashtable.hpp"
#include "utilities/hashtable.inline.hpp"
+#include "utilities/numberSeq.hpp"
// This is a generic hashtable, designed to be used for the symbol
@@ -237,6 +238,57 @@
}
}
+template <class T, MEMFLAGS F> int Hashtable<T, F>::literal_size(Symbol *symbol) {
+ return symbol->size() * HeapWordSize;
+}
+
+template <class T, MEMFLAGS F> int Hashtable<T, F>::literal_size(oop oop) {
+ // NOTE: this would over-count if (pre-JDK8) java_lang_Class::has_offset_field() is true,
+ // and the String.value array is shared by several Strings. However, starting from JDK8,
+ // the String.value array is not shared anymore.
+ assert(oop != NULL && oop->klass() == SystemDictionary::String_klass(), "only strings are supported");
+ return (oop->size() + java_lang_String::value(oop)->size()) * HeapWordSize;
+}
+
+// Dump footprint and bucket length statistics
+//
+// Note: if you create a new subclass of Hashtable<MyNewType, F>, you will need to
+// add a new function Hashtable<T, F>::literal_size(MyNewType lit)
+
+template <class T, MEMFLAGS F> void Hashtable<T, F>::dump_table(outputStream* st, const char *table_name) {
+ NumberSeq summary;
+ int literal_bytes = 0;
+ for (int i = 0; i < this->table_size(); ++i) {
+ int count = 0;
+ for (HashtableEntry<T, F>* e = bucket(i);
+ e != NULL; e = e->next()) {
+ count++;
+ literal_bytes += literal_size(e->literal());
+ }
+ summary.add((double)count);
+ }
+ double num_buckets = summary.num();
+ double num_entries = summary.sum();
+
+ int bucket_bytes = (int)num_buckets * sizeof(bucket(0));
+ int entry_bytes = (int)num_entries * sizeof(HashtableEntry<T, F>);
+ int total_bytes = literal_bytes + bucket_bytes + entry_bytes;
+
+ double bucket_avg = (num_buckets <= 0) ? 0 : (bucket_bytes / num_buckets);
+ double entry_avg = (num_entries <= 0) ? 0 : (entry_bytes / num_entries);
+ double literal_avg = (num_entries <= 0) ? 0 : (literal_bytes / num_entries);
+
+ st->print_cr("%s statistics:", table_name);
+ st->print_cr("Number of buckets : %9d = %9d bytes, avg %7.3f", (int)num_buckets, bucket_bytes, bucket_avg);
+ st->print_cr("Number of entries : %9d = %9d bytes, avg %7.3f", (int)num_entries, entry_bytes, entry_avg);
+ st->print_cr("Number of literals : %9d = %9d bytes, avg %7.3f", (int)num_entries, literal_bytes, literal_avg);
+ st->print_cr("Total footprint : %9s = %9d bytes", "", total_bytes);
+ st->print_cr("Average bucket size : %9.3f", summary.avg());
+ st->print_cr("Variance of bucket size : %9.3f", summary.variance());
+ st->print_cr("Std. dev. of bucket size: %9.3f", summary.sd());
+ st->print_cr("Maximum bucket size : %9d", (int)summary.maximum());
+}
+
// Dump the hash table buckets.
--- a/hotspot/src/share/vm/utilities/hashtable.hpp Fri May 17 17:52:07 2013 -0700
+++ b/hotspot/src/share/vm/utilities/hashtable.hpp Sat May 18 20:41:01 2013 -0700
@@ -282,6 +282,19 @@
static bool use_alternate_hashcode() { return _seed != 0; }
static jint seed() { return _seed; }
+ static int literal_size(Symbol *symbol);
+ static int literal_size(oop oop);
+
+ // The following two are currently not used, but are needed anyway because some
+ // C++ compilers (MacOS and Solaris) force the instantiation of
+ // Hashtable<ConstantPool*, mtClass>::dump_table() even though we never call this function
+ // in the VM code.
+ static int literal_size(ConstantPool *cp) {Unimplemented(); return 0;}
+ static int literal_size(Klass *k) {Unimplemented(); return 0;}
+
+public:
+ void dump_table(outputStream* st, const char *table_name);
+
private:
static jint _seed;
};