< prev index next >
src/hotspot/share/classfile/symbolTable.cpp
Print this page
@@ -25,50 +25,187 @@
#include "precompiled.hpp"
#include "classfile/altHashing.hpp"
#include "classfile/compactHashtable.inline.hpp"
#include "classfile/javaClasses.hpp"
#include "classfile/symbolTable.hpp"
-#include "classfile/systemDictionary.hpp"
-#include "gc/shared/collectedHeap.inline.hpp"
#include "memory/allocation.inline.hpp"
-#include "memory/filemap.hpp"
#include "memory/metaspaceClosure.hpp"
#include "memory/resourceArea.hpp"
#include "oops/oop.inline.hpp"
#include "runtime/atomic.hpp"
-#include "runtime/mutexLocker.hpp"
-#include "runtime/safepointVerifiers.hpp"
+#include "runtime/interfaceSupport.inline.hpp"
+#include "runtime/timerTrace.hpp"
#include "services/diagnosticCommand.hpp"
-#include "utilities/hashtable.inline.hpp"
+#include "utilities/concurrentHashTable.inline.hpp"
+#include "utilities/concurrentHashTableTasks.inline.hpp"
-// --------------------------------------------------------------------------
-// the number of buckets a thread claims
-const int ClaimChunkSize = 32;
+// We used to not resize at all, so let's be conservative
+// and not set it too short before we decide to resize,
+// to match previous startup behavior
+#define PREF_AVG_LIST_LEN 8
+// 2^17 (131,072) is max size, which is about 6.5 times as large
+// as the previous table size (used to be 20,011),
+// which never resized
+#define END_SIZE 17
+// If a chain gets to 100 something might be wrong
+#define REHASH_LEN 100
+// We only get a chance to check whether we need
+// to clean infrequently (on class unloading),
+// so if we have even one dead entry then mark table for cleaning
+#define CLEAN_DEAD_HIGH_WATER_MARK 0.0
+
+#define ON_STACK_BUFFER_LENGTH 128
+// --------------------------------------------------------------------------
SymbolTable* SymbolTable::_the_table = NULL;
+CompactHashtable<Symbol*, char> SymbolTable::_shared_table;
+volatile bool SymbolTable::_alt_hash = false;
+volatile bool SymbolTable::_lookup_shared_first = false;
// Static arena for symbols that are not deallocated
Arena* SymbolTable::_arena = NULL;
-bool SymbolTable::_needs_rehashing = false;
-bool SymbolTable::_lookup_shared_first = false;
-CompactHashtable<Symbol*, char> SymbolTable::_shared_table;
+static juint murmur_seed = 0;
+
+static inline void _log_trace_symboltable_helper(Symbol* sym, const char* msg) {
+#ifndef PRODUCT
+ if (log_is_enabled(Trace, symboltable)) {
+ if (sym->as_quoted_ascii() == NULL) {
+ log_trace(symboltable)("%s [%s]", msg, "NULL");
+ } else {
+ log_trace(symboltable)("%s [%s]", msg, sym->as_quoted_ascii());
+ }
+ }
+#endif // PRODUCT
+}
+
+// Pick hashing algorithm.
+static uintx hash_symbol(const char* s, int len, bool useAlt) {
+ return useAlt ?
+ AltHashing::murmur3_32(murmur_seed, (const jbyte*)s, len) :
+ java_lang_String::hash_code((const jbyte*)s, len);
+}
-Symbol* SymbolTable::allocate_symbol(const u1* name, int len, bool c_heap, TRAPS) {
+static uintx hash_shared_symbol(const char* s, int len) {
+ return java_lang_String::hash_code((const jbyte*)s, len);
+}
+
+class SymbolTableConfig : public SymbolTableHash::BaseConfig {
+private:
+public:
+ static uintx get_hash(Symbol* const& value, bool* is_dead) {
+ *is_dead = (value->refcount() == 0);
+ if (*is_dead) {
+ return 0;
+ } else {
+ return hash_symbol((const char*)value->bytes(), value->utf8_length(), SymbolTable::_alt_hash);
+ }
+ }
+ // We use default allocation/deallocation but counted
+ static void* allocate_node(size_t size, Symbol* const& value) {
+ SymbolTable::item_added();
+ return SymbolTableHash::BaseConfig::allocate_node(size, value);
+ }
+ static void free_node(void* memory, Symbol* const& value) {
+ // We get here either because #1 some threads lost a race
+ // to insert a newly created Symbol, or #2 we are freeing
+ // a symbol during normal cleanup deletion.
+ // If #1, then the symbol can be a permanent (refcount==PERM_REFCOUNT),
+ // or regular newly created one but with refcount==0 (see SymbolTableCreateEntry)
+ // If #2, then the symbol must have refcount==0
+ assert((value->refcount() == PERM_REFCOUNT) || (value->refcount() == 0),
+ "refcount %d", value->refcount());
+ SymbolTable::delete_symbol(value);
+ SymbolTableHash::BaseConfig::free_node(memory, value);
+ SymbolTable::item_removed();
+ }
+};
+
+static size_t log2_ceil(uintx value) {
+ size_t ret;
+ for (ret = 1; ((size_t)1 << ret) < value; ++ret);
+ return ret;
+}
+
+SymbolTable::SymbolTable() : _local_table(NULL), _current_size(0), _has_work(0),
+ _needs_rehashing(false), _items_count(0), _uncleaned_items_count(0),
+ _symbols_removed(0), _symbols_counted(0) {
+
+ size_t start_size_log_2 = log2_ceil(SymbolTableSize);
+ _current_size = ((size_t)1) << start_size_log_2;
+ log_trace(symboltable)("Start size: " SIZE_FORMAT " (" SIZE_FORMAT ")",
+ _current_size, start_size_log_2);
+ _local_table = new SymbolTableHash(start_size_log_2, END_SIZE, REHASH_LEN);
+}
+
+void SymbolTable::delete_symbol(Symbol* sym) {
+ if (sym->refcount() == PERM_REFCOUNT) {
+ MutexLocker ml(SymbolTable_lock); // Protect arena
+ // Deleting permanent symbol should not occur very often (insert race condition),
+ // so log it.
+ _log_trace_symboltable_helper(sym, "Freeing permanent symbol");
+ if (!arena()->Afree(sym, sym->size())) {
+ _log_trace_symboltable_helper(sym, "Leaked permanent symbol");
+ }
+ } else {
+ delete sym;
+ }
+}
+
+void SymbolTable::item_added() {
+ Atomic::inc(&(SymbolTable::the_table()->_items_count));
+}
+
+void SymbolTable::set_item_clean_count(size_t ncl) {
+ Atomic::store(ncl, &(SymbolTable::the_table()->_uncleaned_items_count));
+ log_trace(symboltable)("Set uncleaned items:" SIZE_FORMAT, SymbolTable::the_table()->_uncleaned_items_count);
+}
+
+void SymbolTable::mark_item_clean_count() {
+ if (Atomic::cmpxchg((size_t)1, &(SymbolTable::the_table()->_uncleaned_items_count), (size_t)0) == 0) { // only mark if unset
+ log_trace(symboltable)("Marked uncleaned items:" SIZE_FORMAT, SymbolTable::the_table()->_uncleaned_items_count);
+ }
+}
+
+void SymbolTable::item_removed() {
+ Atomic::inc(&(SymbolTable::the_table()->_symbols_removed));
+ Atomic::dec(&(SymbolTable::the_table()->_items_count));
+}
+
+double SymbolTable::get_load_factor() {
+ return (double)_items_count/_current_size;
+}
+
+double SymbolTable::get_dead_factor() {
+ return (double)_uncleaned_items_count/_current_size;
+}
+
+size_t SymbolTable::table_size(Thread* thread) {
+ return ((size_t)(1)) << _local_table->get_size_log2(thread != NULL ? thread
+ : Thread::current());
+}
+
+void SymbolTable::trigger_concurrent_work() {
+ MutexLockerEx ml(Service_lock, Mutex::_no_safepoint_check_flag);
+ SymbolTable::the_table()->_has_work = true;
+ Service_lock->notify_all();
+}
+
+Symbol* SymbolTable::allocate_symbol(const char* name, int len, bool c_heap, TRAPS) {
assert (len <= Symbol::max_length(), "should be checked by caller");
Symbol* sym;
-
if (DumpSharedSpaces) {
c_heap = false;
}
if (c_heap) {
// refcount starts as 1
- sym = new (len, THREAD) Symbol(name, len, 1);
+ sym = new (len, THREAD) Symbol((const u1*)name, len, 1);
assert(sym != NULL, "new should call vm_exit_out_of_memory if C_HEAP is exhausted");
} else {
// Allocate to global arena
- sym = new (len, arena(), THREAD) Symbol(name, len, PERM_REFCOUNT);
+ MutexLocker ml(SymbolTable_lock); // Protect arena
+ sym = new (len, arena(), THREAD) Symbol((const u1*)name, len, PERM_REFCOUNT);
}
return sym;
}
void SymbolTable::initialize_symbols(int arena_alloc_size) {
@@ -78,647 +215,723 @@
} else {
_arena = new (mtSymbol) Arena(mtSymbol, arena_alloc_size);
}
}
+class SymbolsDo : StackObj {
+ SymbolClosure *_cl;
+public:
+ SymbolsDo(SymbolClosure *cl) : _cl(cl) {}
+ bool operator()(Symbol** value) {
+ assert(value != NULL, "expected valid value");
+ assert(*value != NULL, "value should point to a symbol");
+ _cl->do_symbol(value);
+ return true;
+ };
+};
+
// Call function for all symbols in the symbol table.
void SymbolTable::symbols_do(SymbolClosure *cl) {
// all symbols from shared table
_shared_table.symbols_do(cl);
// all symbols from the dynamic table
- const int n = the_table()->table_size();
- for (int i = 0; i < n; i++) {
- for (HashtableEntry<Symbol*, mtSymbol>* p = the_table()->bucket(i);
- p != NULL;
- p = p->next()) {
- cl->do_symbol(p->literal_addr());
- }
+ SymbolsDo sd(cl);
+ if (!SymbolTable::the_table()->_local_table->try_scan(Thread::current(), sd)) {
+ log_info(stringtable)("symbols_do unavailable at this moment");
}
}
+class MetaspacePointersDo : StackObj {
+ MetaspaceClosure *_it;
+public:
+ MetaspacePointersDo(MetaspaceClosure *it) : _it(it) {}
+ bool operator()(Symbol** value) {
+ assert(value != NULL, "expected valid value");
+ assert(*value != NULL, "value should point to a symbol");
+ _it->push(value);
+ return true;
+ };
+};
+
void SymbolTable::metaspace_pointers_do(MetaspaceClosure* it) {
assert(DumpSharedSpaces, "called only during dump time");
- const int n = the_table()->table_size();
- for (int i = 0; i < n; i++) {
- for (HashtableEntry<Symbol*, mtSymbol>* p = the_table()->bucket(i);
- p != NULL;
- p = p->next()) {
- it->push(p->literal_addr());
- }
- }
-}
-
-int SymbolTable::_symbols_removed = 0;
-int SymbolTable::_symbols_counted = 0;
-volatile int SymbolTable::_parallel_claimed_idx = 0;
-
-void SymbolTable::buckets_unlink(int start_idx, int end_idx, BucketUnlinkContext* context) {
- for (int i = start_idx; i < end_idx; ++i) {
- HashtableEntry<Symbol*, mtSymbol>** p = the_table()->bucket_addr(i);
- HashtableEntry<Symbol*, mtSymbol>* entry = the_table()->bucket(i);
- while (entry != NULL) {
- // Shared entries are normally at the end of the bucket and if we run into
- // a shared entry, then there is nothing more to remove. However, if we
- // have rehashed the table, then the shared entries are no longer at the
- // end of the bucket.
- if (entry->is_shared() && !use_alternate_hashcode()) {
- break;
- }
- Symbol* s = entry->literal();
- context->_num_processed++;
- assert(s != NULL, "just checking");
- // If reference count is zero, remove.
- if (s->refcount() == 0) {
- assert(!entry->is_shared(), "shared entries should be kept live");
- delete s;
- *p = entry->next();
- context->free_entry(entry);
- } else {
- p = entry->next_addr();
- }
- // get next entry
- entry = (HashtableEntry<Symbol*, mtSymbol>*)HashtableEntry<Symbol*, mtSymbol>::make_ptr(*p);
- }
- }
-}
-
-// Remove unreferenced symbols from the symbol table
-// This is done late during GC.
-void SymbolTable::unlink(int* processed, int* removed) {
- BucketUnlinkContext context;
- buckets_unlink(0, the_table()->table_size(), &context);
- _the_table->bulk_free_entries(&context);
- *processed = context._num_processed;
- *removed = context._num_removed;
-
- _symbols_removed = context._num_removed;
- _symbols_counted = context._num_processed;
+ MetaspacePointersDo mpd(it);
+ SymbolTable::the_table()->_local_table->do_scan(Thread::current(), mpd);
}
-void SymbolTable::possibly_parallel_unlink(int* processed, int* removed) {
- const int limit = the_table()->table_size();
-
- BucketUnlinkContext context;
- for (;;) {
- // Grab next set of buckets to scan
- int start_idx = Atomic::add(ClaimChunkSize, &_parallel_claimed_idx) - ClaimChunkSize;
- if (start_idx >= limit) {
- // End of table
- break;
- }
-
- int end_idx = MIN2(limit, start_idx + ClaimChunkSize);
- buckets_unlink(start_idx, end_idx, &context);
- }
-
- _the_table->bulk_free_entries(&context);
- *processed = context._num_processed;
- *removed = context._num_removed;
-
- Atomic::add(context._num_processed, &_symbols_counted);
- Atomic::add(context._num_removed, &_symbols_removed);
-}
-
-// Create a new table and using alternate hash code, populate the new table
-// with the existing strings. Set flag to use the alternate hash code afterwards.
-void SymbolTable::rehash_table() {
- if (DumpSharedSpaces) {
- tty->print_cr("Warning: rehash_table should not be called while dumping archive");
- return;
- }
-
- assert(SafepointSynchronize::is_at_safepoint(), "must be at safepoint");
- // This should never happen with -Xshare:dump but it might in testing mode.
- if (DumpSharedSpaces) return;
-
- // Create a new symbol table
- SymbolTable* new_table = new SymbolTable();
-
- the_table()->move_to(new_table);
-
- // Delete the table and buckets (entries are reused in new table).
- delete _the_table;
- // Don't check if we need rehashing until the table gets unbalanced again.
- // Then rehash with a new global seed.
- _needs_rehashing = false;
- _the_table = new_table;
-}
-
-// Lookup a symbol in a bucket.
-
-Symbol* SymbolTable::lookup_dynamic(int index, const char* name,
+Symbol* SymbolTable::lookup_dynamic(const char* name,
int len, unsigned int hash) {
- int count = 0;
- for (HashtableEntry<Symbol*, mtSymbol>* e = bucket(index); e != NULL; e = e->next()) {
- count++; // count all entries in this bucket, not just ones with same hash
- if (e->hash() == hash) {
- Symbol* sym = e->literal();
- // Skip checking already dead symbols in the bucket.
- if (sym->refcount() == 0) {
- count--; // Don't count this symbol towards rehashing.
- } else if (sym->equals(name, len)) {
- if (sym->try_increment_refcount()) {
- // something is referencing this symbol now.
- return sym;
- } else {
- count--; // don't count this symbol.
- }
- }
- }
- }
- // If the bucket size is too deep check if this hash code is insufficient.
- if (count >= rehash_count && !needs_rehashing()) {
- _needs_rehashing = check_rehash_table(count);
- }
- return NULL;
+ Symbol* sym = SymbolTable::the_table()->do_lookup(name, len, hash);
+ assert((sym == NULL) || sym->refcount() != 0, "refcount must not be zero");
+ return sym;
}
Symbol* SymbolTable::lookup_shared(const char* name,
int len, unsigned int hash) {
- if (use_alternate_hashcode()) {
- // hash_code parameter may use alternate hashing algorithm but the shared table
- // always uses the same original hash code.
- hash = hash_shared_symbol(name, len);
+ if (!_shared_table.empty()) {
+ if (SymbolTable::_alt_hash) {
+ // hash_code parameter may use alternate hashing algorithm but the shared table
+ // always uses the same original hash code.
+ hash = hash_shared_symbol(name, len);
+ }
+ return _shared_table.lookup(name, hash, len);
+ } else {
+ return NULL;
}
- return _shared_table.lookup(name, hash, len);
}
-Symbol* SymbolTable::lookup(int index, const char* name,
+Symbol* SymbolTable::lookup_common(const char* name,
int len, unsigned int hash) {
Symbol* sym;
if (_lookup_shared_first) {
sym = lookup_shared(name, len, hash);
- if (sym != NULL) {
- return sym;
+ if (sym == NULL) {
+ _lookup_shared_first = false;
+ sym = lookup_dynamic(name, len, hash);
}
- _lookup_shared_first = false;
- return lookup_dynamic(index, name, len, hash);
} else {
- sym = lookup_dynamic(index, name, len, hash);
- if (sym != NULL) {
- return sym;
- }
- sym = lookup_shared(name, len, hash);
- if (sym != NULL) {
- _lookup_shared_first = true;
+ sym = lookup_dynamic(name, len, hash);
+ if (sym == NULL) {
+ sym = lookup_shared(name, len, hash);
+ if (sym != NULL) {
+ _lookup_shared_first = true;
+ }
}
- return sym;
}
-}
-
-u4 SymbolTable::encode_shared(Symbol* sym) {
- assert(DumpSharedSpaces, "called only during dump time");
- uintx base_address = uintx(MetaspaceShared::shared_rs()->base());
- uintx offset = uintx(sym) - base_address;
- assert(offset < 0x7fffffff, "sanity");
- return u4(offset);
-}
-
-Symbol* SymbolTable::decode_shared(u4 offset) {
- assert(!DumpSharedSpaces, "called only during runtime");
- uintx base_address = _shared_table.base_address();
- Symbol* sym = (Symbol*)(base_address + offset);
-
-#ifndef PRODUCT
- const char* s = (const char*)sym->bytes();
- int len = sym->utf8_length();
- unsigned int hash = hash_symbol(s, len);
- assert(sym == lookup_shared(s, len, hash), "must be shared symbol");
-#endif
-
return sym;
}
-// Pick hashing algorithm.
-unsigned int SymbolTable::hash_symbol(const char* s, int len) {
- return use_alternate_hashcode() ?
- AltHashing::murmur3_32(seed(), (const jbyte*)s, len) :
- java_lang_String::hash_code((const jbyte*)s, len);
-}
-
-unsigned int SymbolTable::hash_shared_symbol(const char* s, int len) {
- return java_lang_String::hash_code((const jbyte*)s, len);
-}
-
-
-// We take care not to be blocking while holding the
-// SymbolTable_lock. Otherwise, the system might deadlock, since the
-// symboltable is used during compilation (VM_thread) The lock free
-// synchronization is simplified by the fact that we do not delete
-// entries in the symbol table during normal execution (only during
-// safepoints).
-
Symbol* SymbolTable::lookup(const char* name, int len, TRAPS) {
- unsigned int hashValue = hash_symbol(name, len);
- int index = the_table()->hash_to_index(hashValue);
-
- Symbol* s = the_table()->lookup(index, name, len, hashValue);
-
- // Found
- if (s != NULL) return s;
-
- // Grab SymbolTable_lock first.
- MutexLocker ml(SymbolTable_lock, THREAD);
-
- // Otherwise, add to symbol to table
- return the_table()->basic_add(index, (u1*)name, len, hashValue, true, THREAD);
+ unsigned int hash = hash_symbol(name, len, SymbolTable::_alt_hash);
+ Symbol* sym = SymbolTable::the_table()->lookup_common(name, len, hash);
+ if (sym == NULL) {
+ sym = SymbolTable::the_table()->do_add_if_needed(name, len, hash, true, CHECK_NULL);
+ }
+ assert(sym->refcount() != 0, "lookup should have incremented the count");
+ assert(sym->equals(name, len), "symbol must be properly initialized");
+ return sym;
}
Symbol* SymbolTable::lookup(const Symbol* sym, int begin, int end, TRAPS) {
- char* buffer;
- int index, len;
- unsigned int hashValue;
- char* name;
- {
- debug_only(NoSafepointVerifier nsv;)
-
- name = (char*)sym->base() + begin;
- len = end - begin;
- hashValue = hash_symbol(name, len);
- index = the_table()->hash_to_index(hashValue);
- Symbol* s = the_table()->lookup(index, name, len, hashValue);
-
- // Found
- if (s != NULL) return s;
+ assert(sym->refcount() != 0, "require a valid symbol");
+ const char* name = (const char*)sym->base() + begin;
+ int len = end - begin;
+ unsigned int hash = hash_symbol(name, len, SymbolTable::_alt_hash);
+ Symbol* found = SymbolTable::the_table()->lookup_common(name, len, hash);
+ if (found == NULL) {
+ found = SymbolTable::the_table()->do_add_if_needed(name, len, hash, true, THREAD);
+ }
+ return found;
+}
+
+class SymbolTableLookup : StackObj {
+private:
+ Thread* _thread;
+ uintx _hash;
+ int _len;
+ const char* _str;
+public:
+ SymbolTableLookup(Thread* thread, const char* key, int len, uintx hash)
+ : _thread(thread), _hash(hash), _str(key), _len(len) {}
+ uintx get_hash() const {
+ return _hash;
+ }
+ bool equals(Symbol** value, bool* is_dead) {
+ assert(value != NULL, "expected valid value");
+ assert(*value != NULL, "value should point to a symbol");
+ Symbol *sym = *value;
+ if (sym->equals(_str, _len)) {
+ if (sym->try_increment_refcount()) {
+ // something is referencing this symbol now.
+ return true;
+ } else {
+ assert(sym->refcount() == 0, "expected dead symbol");
+ *is_dead = true;
+ return false;
+ }
+ } else {
+ *is_dead = (sym->refcount() == 0);
+ return false;
+ }
}
+};
- // Otherwise, add to symbol to table. Copy to a C string first.
- char stack_buf[128];
- ResourceMark rm(THREAD);
- if (len <= 128) {
- buffer = stack_buf;
- } else {
- buffer = NEW_RESOURCE_ARRAY_IN_THREAD(THREAD, char, len);
+class SymbolTableGet : public StackObj {
+ Symbol* _return;
+public:
+ SymbolTableGet() : _return(NULL) { }
+ void operator()(Symbol** value) {
+ assert(value != NULL, "expected valid value");
+ assert(*value != NULL, "value should point to a symbol");
+ _return = *value;
+ }
+ Symbol* get_res_sym() {
+ return _return;
+ }
+};
+
+Symbol* SymbolTable::do_lookup(const char* name, int len, uintx hash) {
+ Thread* thread = Thread::current();
+ SymbolTableLookup lookup(thread, name, len, hash);
+ SymbolTableGet stg;
+ bool rehash_warning = false;
+ _local_table->get(thread, lookup, stg, &rehash_warning);
+ if (rehash_warning) {
+ _needs_rehashing = true;
}
- for (int i=0; i<len; i++) {
- buffer[i] = name[i];
- }
- // Make sure there is no safepoint in the code above since name can't move.
- // We can't include the code in NoSafepointVerifier because of the
- // ResourceMark.
-
- // Grab SymbolTable_lock first.
- MutexLocker ml(SymbolTable_lock, THREAD);
-
- return the_table()->basic_add(index, (u1*)buffer, len, hashValue, true, THREAD);
-}
-
-Symbol* SymbolTable::lookup_only(const char* name, int len,
- unsigned int& hash) {
- hash = hash_symbol(name, len);
- int index = the_table()->hash_to_index(hash);
-
- Symbol* s = the_table()->lookup(index, name, len, hash);
- return s;
+ Symbol* sym = stg.get_res_sym();
+ assert((sym == NULL) || sym->refcount() != 0, "found dead symbol");
+ return sym;
}
-// Look up the address of the literal in the SymbolTable for this Symbol*
-// Do not create any new symbols
-// Do not increment the reference count to keep this alive
-Symbol** SymbolTable::lookup_symbol_addr(Symbol* sym){
- unsigned int hash = hash_symbol((char*)sym->bytes(), sym->utf8_length());
- int index = the_table()->hash_to_index(hash);
-
- for (HashtableEntry<Symbol*, mtSymbol>* e = the_table()->bucket(index); e != NULL; e = e->next()) {
- if (e->hash() == hash) {
- Symbol* literal_sym = e->literal();
- if (sym == literal_sym) {
- return e->literal_addr();
- }
- }
- }
- return NULL;
+Symbol* SymbolTable::lookup_only(const char* name, int len, unsigned int& hash) {
+ hash = hash_symbol(name, len, SymbolTable::_alt_hash);
+ return SymbolTable::the_table()->lookup_common(name, len, hash);
}
// Suggestion: Push unicode-based lookup all the way into the hashing
// and probing logic, so there is no need for convert_to_utf8 until
// an actual new Symbol* is created.
Symbol* SymbolTable::lookup_unicode(const jchar* name, int utf16_length, TRAPS) {
int utf8_length = UNICODE::utf8_length((jchar*) name, utf16_length);
- char stack_buf[128];
+ char stack_buf[ON_STACK_BUFFER_LENGTH];
if (utf8_length < (int) sizeof(stack_buf)) {
char* chars = stack_buf;
UNICODE::convert_to_utf8(name, utf16_length, chars);
return lookup(chars, utf8_length, THREAD);
} else {
ResourceMark rm(THREAD);
- char* chars = NEW_RESOURCE_ARRAY(char, utf8_length + 1);;
+ char* chars = NEW_RESOURCE_ARRAY(char, utf8_length + 1);
UNICODE::convert_to_utf8(name, utf16_length, chars);
return lookup(chars, utf8_length, THREAD);
}
}
Symbol* SymbolTable::lookup_only_unicode(const jchar* name, int utf16_length,
unsigned int& hash) {
int utf8_length = UNICODE::utf8_length((jchar*) name, utf16_length);
- char stack_buf[128];
+ char stack_buf[ON_STACK_BUFFER_LENGTH];
if (utf8_length < (int) sizeof(stack_buf)) {
char* chars = stack_buf;
UNICODE::convert_to_utf8(name, utf16_length, chars);
return lookup_only(chars, utf8_length, hash);
} else {
ResourceMark rm;
- char* chars = NEW_RESOURCE_ARRAY(char, utf8_length + 1);;
+ char* chars = NEW_RESOURCE_ARRAY(char, utf8_length + 1);
UNICODE::convert_to_utf8(name, utf16_length, chars);
return lookup_only(chars, utf8_length, hash);
}
}
void SymbolTable::add(ClassLoaderData* loader_data, const constantPoolHandle& cp,
- int names_count,
- const char** names, int* lengths, int* cp_indices,
- unsigned int* hashValues, TRAPS) {
- // Grab SymbolTable_lock first.
- MutexLocker ml(SymbolTable_lock, THREAD);
-
- SymbolTable* table = the_table();
- bool added = table->basic_add(loader_data, cp, names_count, names, lengths,
- cp_indices, hashValues, CHECK);
- if (!added) {
- // do it the hard way
- for (int i=0; i<names_count; i++) {
- int index = table->hash_to_index(hashValues[i]);
- bool c_heap = !loader_data->is_the_null_class_loader_data();
- Symbol* sym = table->basic_add(index, (u1*)names[i], lengths[i], hashValues[i], c_heap, CHECK);
- cp->symbol_at_put(cp_indices[i], sym);
+ int names_count, const char** names, int* lengths,
+ int* cp_indices, unsigned int* hashValues, TRAPS) {
+ bool c_heap = !loader_data->is_the_null_class_loader_data();
+ for (int i = 0; i < names_count; i++) {
+ const char *name = names[i];
+ int len = lengths[i];
+ unsigned int hash = hashValues[i];
+ Symbol* sym = SymbolTable::the_table()->lookup_common(name, len, hash);
+ if (sym == NULL) {
+ sym = SymbolTable::the_table()->do_add_if_needed(name, len, hash, c_heap, CHECK);
+ }
+ assert(sym->refcount() != 0, "lookup should have incremented the count");
+ cp->symbol_at_put(cp_indices[i], sym);
+ }
+}
+
+class SymbolTableCreateEntry : public StackObj {
+private:
+ Thread* _thread;
+ const char* _name;
+ int _len;
+ bool _heap;
+ Symbol* _return;
+ Symbol* _created;
+
+ void assert_for_name(Symbol* sym, const char* where) const {
+#ifdef ASSERT
+ assert(sym->utf8_length() == _len, "%s [%d,%d]", where, sym->utf8_length(), _len);
+ for (int i = 0; i < _len; i++) {
+ assert(sym->byte_at(i) == _name[i],
+ "%s [%d,%d,%d]", where, i, sym->byte_at(i), _name[i]);
+ }
+#endif
+ }
+
+public:
+ SymbolTableCreateEntry(Thread* thread, const char* name, int len, bool heap)
+ : _thread(thread), _name(name) , _len(len), _heap(heap), _return(NULL) , _created(NULL) {
+ assert(_name != NULL, "expected valid name");
+ }
+ Symbol* operator()() {
+ _created = SymbolTable::the_table()->allocate_symbol(_name, _len, _heap, _thread);
+ assert(_created != NULL, "expected created symbol");
+ assert_for_name(_created, "operator()()");
+ assert(_created->equals(_name, _len),
+ "symbol must be properly initialized [%p,%d,%d]", _name, _len, (int)_heap);
+ return _created;
+ }
+ void operator()(bool inserted, Symbol** value) {
+ assert(value != NULL, "expected valid value");
+ assert(*value != NULL, "value should point to a symbol");
+ if (!inserted && (_created != NULL)) {
+ // We created our symbol, but someone else inserted
+ // theirs first, so ours will be destroyed.
+ // Since symbols are created with refcount of 1,
+ // we must decrement it here to 0 to delete,
+ // unless it's a permanent one.
+ if (_created->refcount() != PERM_REFCOUNT) {
+ assert(_created->refcount() == 1, "expected newly created symbol");
+ _created->decrement_refcount();
+ assert(_created->refcount() == 0, "expected dead symbol");
+ }
}
+ _return = *value;
+ assert_for_name(_return, "operator()");
+ }
+ Symbol* get_new_sym() const {
+ assert_for_name(_return, "get_new_sym");
+ return _return;
+ }
+};
+
+Symbol* SymbolTable::do_add_if_needed(const char* name, int len, uintx hash, bool heap, TRAPS) {
+ SymbolTableLookup lookup(THREAD, name, len, hash);
+ SymbolTableCreateEntry stce(THREAD, name, len, heap);
+ bool rehash_warning = false;
+ bool clean_hint = false;
+ _local_table->get_insert_lazy(THREAD, lookup, stce, stce, &rehash_warning, &clean_hint);
+ if (rehash_warning) {
+ _needs_rehashing = true;
+ }
+ if (clean_hint) {
+ // we just found out that there is a dead item,
+ // which we were unable to clean right now,
+ // but we have no way of telling whether it's
+ // been previously counted or not, so mark
+ // it only if no other items were found yet
+ mark_item_clean_count();
+ check_concurrent_work();
}
+ Symbol* sym = stce.get_new_sym();
+ assert(sym->refcount() != 0, "zero is invalid");
+ return sym;
}
Symbol* SymbolTable::new_permanent_symbol(const char* name, TRAPS) {
- unsigned int hash;
- Symbol* result = SymbolTable::lookup_only((char*)name, (int)strlen(name), hash);
- if (result != NULL) {
- return result;
+ unsigned int hash = 0;
+ int len = (int)strlen(name);
+ Symbol* sym = SymbolTable::lookup_only(name, len, hash);
+ if (sym == NULL) {
+ sym = SymbolTable::the_table()->do_add_if_needed(name, len, hash, false, CHECK_NULL);
+ }
+ if (sym->refcount() != PERM_REFCOUNT) {
+ sym->increment_refcount();
+ _log_trace_symboltable_helper(sym, "Asked for a permanent symbol, but got a regular one");
}
- // Grab SymbolTable_lock first.
- MutexLocker ml(SymbolTable_lock, THREAD);
-
- SymbolTable* table = the_table();
- int index = table->hash_to_index(hash);
- return table->basic_add(index, (u1*)name, (int)strlen(name), hash, false, THREAD);
+ return sym;
}
-Symbol* SymbolTable::basic_add(int index_arg, u1 *name, int len,
- unsigned int hashValue_arg, bool c_heap, TRAPS) {
- assert(!Universe::heap()->is_in_reserved(name),
- "proposed name of symbol must be stable");
+struct SizeFunc : StackObj {
+ size_t operator()(Symbol** value) {
+ assert(value != NULL, "expected valid value");
+ assert(*value != NULL, "value should point to a symbol");
+ return (*value)->size() * HeapWordSize;
+ };
+};
+
+void SymbolTable::print_table_statistics(outputStream* st,
+ const char* table_name) {
+ SizeFunc sz;
+ _local_table->statistics_to(Thread::current(), sz, st, table_name);
+}
+
+// Verification
+class VerifySymbols : StackObj {
+public:
+ bool operator()(Symbol** value) {
+ guarantee(value != NULL, "expected valid value");
+ guarantee(*value != NULL, "value should point to a symbol");
+ Symbol* sym = *value;
+ guarantee(sym->equals((const char*)sym->bytes(), sym->utf8_length()),
+ "symbol must be internally consistent");
+ return true;
+ };
+};
- // Don't allow symbols to be created which cannot fit in a Symbol*.
- if (len > Symbol::max_length()) {
- THROW_MSG_0(vmSymbols::java_lang_InternalError(),
- "name is too long to represent");
+void SymbolTable::verify() {
+ Thread* thr = Thread::current();
+ VerifySymbols vs;
+ if (!SymbolTable::the_table()->_local_table->try_scan(thr, vs)) {
+ log_info(stringtable)("verify unavailable at this moment");
}
+}
- // Cannot hit a safepoint in this function because the "this" pointer can move.
- NoSafepointVerifier nsv;
+// Dumping
+class DumpSymbol : StackObj {
+ Thread* _thr;
+ outputStream* _st;
+public:
+ DumpSymbol(Thread* thr, outputStream* st) : _thr(thr), _st(st) {}
+ bool operator()(Symbol** value) {
+ assert(value != NULL, "expected valid value");
+ assert(*value != NULL, "value should point to a symbol");
+ Symbol* sym = *value;
+ const char* utf8_string = (const char*)sym->bytes();
+ int utf8_length = sym->utf8_length();
+ _st->print("%d %d: ", utf8_length, sym->refcount());
+ HashtableTextDump::put_utf8(_st, utf8_string, utf8_length);
+ _st->cr();
+ return true;
+ };
+};
- // Check if the symbol table has been rehashed, if so, need to recalculate
- // the hash value and index.
- unsigned int hashValue;
- int index;
- if (use_alternate_hashcode()) {
- hashValue = hash_symbol((const char*)name, len);
- index = hash_to_index(hashValue);
+void SymbolTable::dump(outputStream* st, bool verbose) {
+ if (!verbose) {
+ SymbolTable::the_table()->print_table_statistics(st, "SymbolTable");
} else {
- hashValue = hashValue_arg;
- index = index_arg;
+ Thread* thr = Thread::current();
+ ResourceMark rm(thr);
+ st->print_cr("VERSION: 1.1");
+ DumpSymbol ds(thr, st);
+ if (!SymbolTable::the_table()->_local_table->try_scan(thr, ds)) {
+ log_info(symboltable)("dump unavailable at this moment");
+ }
}
+}
- // Since look-up was done lock-free, we need to check if another
- // thread beat us in the race to insert the symbol.
- Symbol* test = lookup(index, (char*)name, len, hashValue);
- if (test != NULL) {
- // A race occurred and another thread introduced the symbol.
- assert(test->refcount() != 0, "lookup should have incremented the count");
- return test;
- }
+#if INCLUDE_CDS
+struct CopyToArchive : StackObj {
+ CompactSymbolTableWriter* _writer;
+ CopyToArchive(CompactSymbolTableWriter* writer) : _writer(writer) {}
+ bool operator()(Symbol** value) {
+ assert(value != NULL, "expected valid value");
+ assert(*value != NULL, "value should point to a symbol");
+ Symbol* sym = *value;
+ unsigned int fixed_hash = hash_shared_symbol((const char*)sym->bytes(), sym->utf8_length());
+ if (fixed_hash == 0) {
+ return true;
+ }
+ assert(fixed_hash == hash_symbol((const char*)sym->bytes(), sym->utf8_length(), false),
+ "must not rehash during dumping");
+
+ // add to the compact table
+ _writer->add(fixed_hash, sym);
+
+ return true;
+ }
+};
+
+void SymbolTable::copy_shared_symbol_table(CompactSymbolTableWriter* writer) {
+ CopyToArchive copy(writer);
+ SymbolTable::the_table()->_local_table->do_scan(Thread::current(), copy);
+}
- // Create a new symbol.
- Symbol* sym = allocate_symbol(name, len, c_heap, CHECK_NULL);
- assert(sym->equals((char*)name, len), "symbol must be properly initialized");
+void SymbolTable::write_to_archive() {
+ _shared_table.reset();
- HashtableEntry<Symbol*, mtSymbol>* entry = new_entry(hashValue, sym);
- add_entry(index, entry);
- return sym;
+ int num_buckets = (SymbolTable::the_table()->_items_count / SharedSymbolTableBucketSize);
+ // calculation of num_buckets can result in zero buckets, we need at least one
+ CompactSymbolTableWriter writer(num_buckets > 1 ? num_buckets : 1,
+ &MetaspaceShared::stats()->symbol);
+ copy_shared_symbol_table(&writer);
+ writer.dump(&_shared_table);
+
+ // Verify table is correct
+ Symbol* sym = vmSymbols::java_lang_Object();
+ const char* name = (const char*)sym->bytes();
+ int len = sym->utf8_length();
+ unsigned int hash = hash_symbol(name, len, SymbolTable::_alt_hash);
+ assert(sym == _shared_table.lookup(name, hash, len), "sanity");
}
-// This version of basic_add adds symbols in batch from the constant pool
-// parsing.
-bool SymbolTable::basic_add(ClassLoaderData* loader_data, const constantPoolHandle& cp,
- int names_count,
- const char** names, int* lengths,
- int* cp_indices, unsigned int* hashValues,
- TRAPS) {
-
- // Check symbol names are not too long. If any are too long, don't add any.
- for (int i = 0; i< names_count; i++) {
- if (lengths[i] > Symbol::max_length()) {
- THROW_MSG_0(vmSymbols::java_lang_InternalError(),
- "name is too long to represent");
- }
+void SymbolTable::serialize(SerializeClosure* soc) {
+ _shared_table.set_type(CompactHashtable<Symbol*, char>::_symbol_table);
+ _shared_table.serialize(soc);
+
+ if (soc->writing()) {
+ // Sanity. Make sure we don't use the shared table at dump time
+ _shared_table.reset();
}
+}
+#endif //INCLUDE_CDS
- // Cannot hit a safepoint in this function because the "this" pointer can move.
- NoSafepointVerifier nsv;
-
- for (int i=0; i<names_count; i++) {
- // Check if the symbol table has been rehashed, if so, need to recalculate
- // the hash value.
- unsigned int hashValue;
- if (use_alternate_hashcode()) {
- hashValue = hash_symbol(names[i], lengths[i]);
- } else {
- hashValue = hashValues[i];
+// Concurrent work
+void SymbolTable::grow(JavaThread* jt) {
+ SymbolTableHash::GrowTask gt(_local_table);
+ if (!gt.prepare(jt)) {
+ return;
+ }
+ log_trace(symboltable)("Started to grow");
+ {
+ TraceTime timer("Grow", TRACETIME_LOG(Debug, symboltable, perf));
+ while (gt.do_task(jt)) {
+ gt.pause(jt);
+ {
+ ThreadBlockInVM tbivm(jt);
+ }
+ gt.cont(jt);
}
- // Since look-up was done lock-free, we need to check if another
- // thread beat us in the race to insert the symbol.
- int index = hash_to_index(hashValue);
- Symbol* test = lookup(index, names[i], lengths[i], hashValue);
- if (test != NULL) {
- // A race occurred and another thread introduced the symbol, this one
- // will be dropped and collected. Use test instead.
- cp->symbol_at_put(cp_indices[i], test);
- assert(test->refcount() != 0, "lookup should have incremented the count");
- } else {
- // Create a new symbol. The null class loader is never unloaded so these
- // are allocated specially in a permanent arena.
- bool c_heap = !loader_data->is_the_null_class_loader_data();
- Symbol* sym = allocate_symbol((const u1*)names[i], lengths[i], c_heap, CHECK_(false));
- assert(sym->equals(names[i], lengths[i]), "symbol must be properly initialized"); // why wouldn't it be???
- HashtableEntry<Symbol*, mtSymbol>* entry = new_entry(hashValue, sym);
- add_entry(index, entry);
- cp->symbol_at_put(cp_indices[i], sym);
+ }
+ gt.done(jt);
+ _current_size = table_size(jt);
+ log_debug(symboltable)("Grown to size:" SIZE_FORMAT, _current_size);
+}
+
+struct SymbolTableDoDelete : StackObj {
+ int _deleted;
+ SymbolTableDoDelete() : _deleted(0) {}
+ void operator()(Symbol** value) {
+ assert(value != NULL, "expected valid value");
+ assert(*value != NULL, "value should point to a symbol");
+ Symbol *sym = *value;
+ assert(sym->refcount() == 0, "refcount");
+ _deleted++;
+ }
+};
+
+struct SymbolTableDeleteCheck : StackObj {
+ int _processed;
+ SymbolTableDeleteCheck() : _processed(0) {}
+ bool operator()(Symbol** value) {
+ assert(value != NULL, "expected valid value");
+ assert(*value != NULL, "value should point to a symbol");
+ _processed++;
+ Symbol *sym = *value;
+ return (sym->refcount() == 0);
+ }
+};
+
+void SymbolTable::clean_dead_entries(JavaThread* jt) {
+ SymbolTableHash::BulkDeleteTask bdt(_local_table);
+ if (!bdt.prepare(jt)) {
+ return;
+ }
+
+ SymbolTableDeleteCheck stdc;
+ SymbolTableDoDelete stdd;
+ {
+ TraceTime timer("Clean", TRACETIME_LOG(Debug, symboltable, perf));
+ while (bdt.do_task(jt, stdc, stdd)) {
+ bdt.pause(jt);
+ {
+ ThreadBlockInVM tbivm(jt);
+ }
+ bdt.cont(jt);
}
+ SymbolTable::the_table()->set_item_clean_count(0);
+ bdt.done(jt);
}
- return true;
+
+ Atomic::add((size_t)stdc._processed, &_symbols_counted);
+
+ log_debug(symboltable)("Cleaned " INT32_FORMAT " of " INT32_FORMAT,
+ stdd._deleted, stdc._processed);
}
+void SymbolTable::check_concurrent_work() {
+ if (_has_work) {
+ return;
+ }
+ double load_factor = SymbolTable::get_load_factor();
+ double dead_factor = SymbolTable::get_dead_factor();
+ // We should clean/resize if we have more dead than alive,
+ // more items than preferred load factor or
+ // more dead items than water mark.
+ if ((dead_factor > load_factor) ||
+ (load_factor > PREF_AVG_LIST_LEN) ||
+ (dead_factor > CLEAN_DEAD_HIGH_WATER_MARK)) {
+ log_debug(symboltable)("Concurrent work triggered, live factor:%f dead factor:%f",
+ load_factor, dead_factor);
+ trigger_concurrent_work();
+ }
+}
-void SymbolTable::verify() {
- for (int i = 0; i < the_table()->table_size(); ++i) {
- HashtableEntry<Symbol*, mtSymbol>* p = the_table()->bucket(i);
- for ( ; p != NULL; p = p->next()) {
- Symbol* s = (Symbol*)(p->literal());
- guarantee(s != NULL, "symbol is NULL");
- unsigned int h = hash_symbol((char*)s->bytes(), s->utf8_length());
- guarantee(p->hash() == h, "broken hash in symbol table entry");
- guarantee(the_table()->hash_to_index(h) == i,
- "wrong index in symbol table");
- }
+void SymbolTable::concurrent_work(JavaThread* jt) {
+ double load_factor = get_load_factor();
+ log_debug(symboltable, perf)("Concurrent work, live factor: %g", load_factor);
+ // We prefer growing, since that also removes dead items
+ if (load_factor > PREF_AVG_LIST_LEN && !_local_table->is_max_size_reached()) {
+ grow(jt);
+ } else {
+ clean_dead_entries(jt);
}
+ _has_work = false;
}
-void SymbolTable::dump(outputStream* st, bool verbose) {
- if (!verbose) {
- the_table()->print_table_statistics(st, "SymbolTable");
+class CountDead : StackObj {
+ int _count;
+public:
+ CountDead() : _count(0) {}
+ bool operator()(Symbol** value) {
+ assert(value != NULL, "expected valid value");
+ assert(*value != NULL, "value should point to a symbol");
+ Symbol* sym = *value;
+ if (sym->refcount() == 0) {
+ _count++;
+ }
+ return true;
+ };
+ int get_dead_count() {
+ return _count;
+ }
+};
+
+void SymbolTable::do_check_concurrent_work() {
+ CountDead counter;
+ if (!SymbolTable::the_table()->_local_table->try_scan(Thread::current(), counter)) {
+ log_info(symboltable)("count dead unavailable at this moment");
} else {
- st->print_cr("VERSION: 1.0");
- for (int i = 0; i < the_table()->table_size(); ++i) {
- HashtableEntry<Symbol*, mtSymbol>* p = the_table()->bucket(i);
- for ( ; p != NULL; p = p->next()) {
- Symbol* s = (Symbol*)(p->literal());
- const char* utf8_string = (const char*)s->bytes();
- int utf8_length = s->utf8_length();
- st->print("%d %d: ", utf8_length, s->refcount());
- HashtableTextDump::put_utf8(st, utf8_string, utf8_length);
- st->cr();
- }
- }
+ SymbolTable::the_table()->set_item_clean_count(counter.get_dead_count());
+ SymbolTable::the_table()->check_concurrent_work();
}
}
-void SymbolTable::write_to_archive() {
-#if INCLUDE_CDS
- _shared_table.reset();
+void SymbolTable::do_concurrent_work(JavaThread* jt) {
+ SymbolTable::the_table()->concurrent_work(jt);
+}
- int num_buckets = the_table()->number_of_entries() /
- SharedSymbolTableBucketSize;
- CompactSymbolTableWriter writer(num_buckets,
- &MetaspaceShared::stats()->symbol);
- for (int i = 0; i < the_table()->table_size(); ++i) {
- HashtableEntry<Symbol*, mtSymbol>* p = the_table()->bucket(i);
- for ( ; p != NULL; p = p->next()) {
- Symbol* s = (Symbol*)(p->literal());
- unsigned int fixed_hash = hash_shared_symbol((char*)s->bytes(), s->utf8_length());
- assert(fixed_hash == p->hash(), "must not rehash during dumping");
- writer.add(fixed_hash, s);
- }
- }
+// Rehash
+bool SymbolTable::do_rehash() {
+ if (!_local_table->is_safepoint_safe()) {
+ return false;
+ }
- writer.dump(&_shared_table);
+ // We use max size
+ SymbolTableHash* new_table = new SymbolTableHash(END_SIZE, END_SIZE, REHASH_LEN);
+ // Use alt hash from now on
+ _alt_hash = true;
+ if (!_local_table->try_move_nodes_to(Thread::current(), new_table)) {
+ _alt_hash = false;
+ delete new_table;
+ return false;
+ }
- // Verify table is correct
- Symbol* sym = vmSymbols::java_lang_Object();
- const char* name = (const char*)sym->bytes();
- int len = sym->utf8_length();
- unsigned int hash = hash_symbol(name, len);
- assert(sym == _shared_table.lookup(name, hash, len), "sanity");
-#endif
+ // free old table
+ delete _local_table;
+ _local_table = new_table;
+
+ return true;
}
-void SymbolTable::serialize(SerializeClosure* soc) {
-#if INCLUDE_CDS
- _shared_table.set_type(CompactHashtable<Symbol*, char>::_symbol_table);
- _shared_table.serialize(soc);
+void SymbolTable::try_rehash_table() {
+ static bool rehashed = false;
+ log_debug(symboltable)("Table imbalanced, rehashing called.");
+
+ // Grow instead of rehash.
+ if (get_load_factor() > PREF_AVG_LIST_LEN &&
+ !_local_table->is_max_size_reached()) {
+ log_debug(symboltable)("Choosing growing over rehashing.");
+ trigger_concurrent_work();
+ _needs_rehashing = false;
+ return;
+ }
- if (soc->writing()) {
- // Sanity. Make sure we don't use the shared table at dump time
- _shared_table.reset();
+ // Already rehashed.
+ if (rehashed) {
+ log_warning(symboltable)("Rehashing already done, still long lists.");
+ trigger_concurrent_work();
+ _needs_rehashing = false;
+ return;
}
-#endif
+
+ murmur_seed = AltHashing::compute_seed();
+
+ if (do_rehash()) {
+ rehashed = true;
+ } else {
+ log_info(symboltable)("Resizes in progress rehashing skipped.");
+ }
+
+ _needs_rehashing = false;
+}
+
+void SymbolTable::rehash_table() {
+ SymbolTable::the_table()->try_rehash_table();
}
//---------------------------------------------------------------------------
// Non-product code
#ifndef PRODUCT
-void SymbolTable::print_histogram() {
- MutexLocker ml(SymbolTable_lock);
- const int results_length = 100;
- int counts[results_length];
- int sizes[results_length];
- int i,j;
-
- // initialize results to zero
- for (j = 0; j < results_length; j++) {
- counts[j] = 0;
- sizes[j] = 0;
- }
-
- int total_size = 0;
- int total_count = 0;
- int total_length = 0;
- int max_length = 0;
- int out_of_range_count = 0;
- int out_of_range_size = 0;
- for (i = 0; i < the_table()->table_size(); i++) {
- HashtableEntry<Symbol*, mtSymbol>* p = the_table()->bucket(i);
- for ( ; p != NULL; p = p->next()) {
- int size = p->literal()->size();
- int len = p->literal()->utf8_length();
- if (len < results_length) {
- counts[len]++;
- sizes[len] += size;
- } else {
- out_of_range_count++;
- out_of_range_size += size;
- }
- total_count++;
- total_size += size;
- total_length += len;
- max_length = MAX2(max_length, len);
+class HistogramIterator : StackObj {
+public:
+ static const size_t results_length = 100;
+ size_t counts[results_length];
+ size_t sizes[results_length];
+ size_t total_size;
+ size_t total_count;
+ size_t total_length;
+ size_t max_length;
+ size_t out_of_range_count;
+ size_t out_of_range_size;
+ HistogramIterator() : total_size(0), total_count(0), total_length(0),
+ max_length(0), out_of_range_count(0), out_of_range_size(0) {
+ // initialize results to zero
+ for (size_t i = 0; i < results_length; i++) {
+ counts[i] = 0;
+ sizes[i] = 0;
+ }
+ }
+ bool operator()(Symbol** value) {
+ assert(value != NULL, "expected valid value");
+ assert(*value != NULL, "value should point to a symbol");
+ Symbol* sym = *value;
+ size_t size = sym->size();
+ size_t len = sym->utf8_length();
+ if (len < results_length) {
+ counts[len]++;
+ sizes[len] += size;
+ } else {
+ out_of_range_count++;
+ out_of_range_size += size;
}
- }
+ total_count++;
+ total_size += size;
+ total_length += len;
+ max_length = MAX2(max_length, len);
+
+ return true;
+ };
+};
+
+void SymbolTable::print_histogram() {
+ SymbolTable* st = SymbolTable::the_table();
+ HistogramIterator hi;
+ st->_local_table->do_scan(Thread::current(), hi);
tty->print_cr("Symbol Table Histogram:");
- tty->print_cr(" Total number of symbols %7d", total_count);
- tty->print_cr(" Total size in memory %7dK",
- (total_size*wordSize)/1024);
- tty->print_cr(" Total counted %7d", _symbols_counted);
- tty->print_cr(" Total removed %7d", _symbols_removed);
- if (_symbols_counted > 0) {
+ tty->print_cr(" Total number of symbols " SIZE_FORMAT_W(7), hi.total_count);
+ tty->print_cr(" Total size in memory " SIZE_FORMAT_W(7) "K",
+ (hi.total_size * wordSize) / 1024);
+ tty->print_cr(" Total counted " SIZE_FORMAT_W(7), st->_symbols_counted);
+ tty->print_cr(" Total removed " SIZE_FORMAT_W(7), st->_symbols_removed);
+ if (SymbolTable::the_table()->_symbols_counted > 0) {
tty->print_cr(" Percent removed %3.2f",
- ((float)_symbols_removed/(float)_symbols_counted)* 100);
+ ((float)st->_symbols_removed / st->_symbols_counted) * 100);
}
- tty->print_cr(" Reference counts %7d", Symbol::_total_count);
- tty->print_cr(" Symbol arena used " SIZE_FORMAT_W(7) "K", arena()->used()/1024);
- tty->print_cr(" Symbol arena size " SIZE_FORMAT_W(7) "K", arena()->size_in_bytes()/1024);
- tty->print_cr(" Total symbol length %7d", total_length);
- tty->print_cr(" Maximum symbol length %7d", max_length);
- tty->print_cr(" Average symbol length %7.2f", ((float) total_length / (float) total_count));
+ tty->print_cr(" Reference counts " SIZE_FORMAT_W(7), Symbol::_total_count);
+ tty->print_cr(" Symbol arena used " SIZE_FORMAT_W(7) "K", arena()->used() / 1024);
+ tty->print_cr(" Symbol arena size " SIZE_FORMAT_W(7) "K", arena()->size_in_bytes() / 1024);
+ tty->print_cr(" Total symbol length " SIZE_FORMAT_W(7), hi.total_length);
+ tty->print_cr(" Maximum symbol length " SIZE_FORMAT_W(7), hi.max_length);
+ tty->print_cr(" Average symbol length %7.2f", ((float)hi.total_length / hi.total_count));
tty->print_cr(" Symbol length histogram:");
tty->print_cr(" %6s %10s %10s", "Length", "#Symbols", "Size");
- for (i = 0; i < results_length; i++) {
- if (counts[i] > 0) {
- tty->print_cr(" %6d %10d %10dK", i, counts[i], (sizes[i]*wordSize)/1024);
- }
- }
- tty->print_cr(" >=%6d %10d %10dK\n", results_length,
- out_of_range_count, (out_of_range_size*wordSize)/1024);
-}
-
-void SymbolTable::print() {
- for (int i = 0; i < the_table()->table_size(); ++i) {
- HashtableEntry<Symbol*, mtSymbol>** p = the_table()->bucket_addr(i);
- HashtableEntry<Symbol*, mtSymbol>* entry = the_table()->bucket(i);
- if (entry != NULL) {
- while (entry != NULL) {
- tty->print(PTR_FORMAT " ", p2i(entry->literal()));
- entry->literal()->print();
- tty->print(" %d", entry->literal()->refcount());
- p = entry->next_addr();
- entry = (HashtableEntry<Symbol*, mtSymbol>*)HashtableEntry<Symbol*, mtSymbol>::make_ptr(*p);
- }
- tty->cr();
+ for (size_t i = 0; i < hi.results_length; i++) {
+ if (hi.counts[i] > 0) {
+ tty->print_cr(" " SIZE_FORMAT_W(6) " " SIZE_FORMAT_W(10) " " SIZE_FORMAT_W(10) "K",
+ i, hi.counts[i], (hi.sizes[i] * wordSize) / 1024);
}
}
+ tty->print_cr(" >=" SIZE_FORMAT_W(6) " " SIZE_FORMAT_W(10) " " SIZE_FORMAT_W(10) "K\n",
+ hi.results_length, hi.out_of_range_count, (hi.out_of_range_size*wordSize) / 1024);
}
#endif // PRODUCT
-
// Utility for dumping symbols
SymboltableDCmd::SymboltableDCmd(outputStream* output, bool heap) :
DCmdWithParser(output, heap),
_verbose("-verbose", "Dump the content of each symbol in the table",
"BOOLEAN", false, "false") {
< prev index next >