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8014262: PrintStringTableStatistics should include more footprint info

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Added info for the string/symbol objects and the hash entries

Reviewed-by: coleenp, rbackman
This commit is contained in:
Ioi Lam 2013-05-18 20:41:01 -07:00
parent 4410135e9e
commit f9ae3b46de
3 changed files with 67 additions and 31 deletions
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52
hotspot/src/share/vm/utilities/hashtable.cpp
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@ -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> void Hashtable<T, F>::reverse(void* boundary) {
}
}
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.