jdk8-mips64-public/hotspot: src/share/vm/utilities/hashtable.cpp@ce9a710b0f63 (annotated)

src/share/vm/utilities/hashtable.cpp@ce9a710b0f63 (annotated)

src/share/vm/utilities/hashtable.cpp

Mon, 15 May 2017 12:20:15 +0200

author: tschatzl
date: Mon, 15 May 2017 12:20:15 +0200
changeset 8766: ce9a710b0f63
parent 7208: 7baf47cb97cb
child 8856: ac27a9c85bea
child 9614: bb44c0e88235
permissions: -rw-r--r--

8180048: Interned string and symbol table leak memory during parallel unlinking
Summary: Make appending found dead BasicHashtableEntrys to the free list atomic.
Reviewed-by: ehelin, shade

 /*
  * Copyright (c) 2003, 2017, 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
  * under the terms of the GNU General Public License version 2 only, as
  * published by the Free Software Foundation.
  *
  * This code is distributed in the hope that it will be useful, but WITHOUT
  * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
  * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
  * version 2 for more details (a copy is included in the LICENSE file that
  * accompanied this code).
  *
  * You should have received a copy of the GNU General Public License version
  * 2 along with this work; if not, write to the Free Software Foundation,
  * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
  *
  * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
  * or visit www.oracle.com if you need additional information or have any
  * questions.
  *
  */
 #include "precompiled.hpp"
 #include "classfile/altHashing.hpp"
 #include "classfile/javaClasses.hpp"
 #include "memory/allocation.inline.hpp"
 #include "memory/filemap.hpp"
 #include "memory/resourceArea.hpp"
 #include "oops/oop.inline.hpp"
 #include "runtime/safepoint.hpp"
 #include "utilities/dtrace.hpp"
 #include "utilities/hashtable.hpp"
 #include "utilities/hashtable.inline.hpp"
 #include "utilities/numberSeq.hpp"
 // This hashtable is implemented as an open hash table with a fixed number of buckets.
 template <MEMFLAGS F> BasicHashtableEntry<F>* BasicHashtable<F>::new_entry_free_list() {
   BasicHashtableEntry<F>* entry = NULL;
   if (_free_list != NULL) {
     entry = _free_list;
     _free_list = _free_list->next();
   }
   return entry;
 }
 // HashtableEntrys are allocated in blocks to reduce the space overhead.
 template <MEMFLAGS F> BasicHashtableEntry<F>* BasicHashtable<F>::new_entry(unsigned int hashValue) {
   BasicHashtableEntry<F>* entry = new_entry_free_list();
   if (entry == NULL) {
     if (_first_free_entry + _entry_size >= _end_block) {
       int block_size = MIN2(512, MAX2((int)_table_size / 2, (int)_number_of_entries));
       int len = _entry_size * block_size;
       len = 1 << log2_intptr(len); // round down to power of 2
       assert(len >= _entry_size, "");
       _first_free_entry = NEW_C_HEAP_ARRAY2(char, len, F, CURRENT_PC);
       _end_block = _first_free_entry + len;
     }
     entry = (BasicHashtableEntry<F>*)_first_free_entry;
     _first_free_entry += _entry_size;
   }
   assert(_entry_size % HeapWordSize == 0, "");
   entry->set_hash(hashValue);
   return entry;
 }
 template <class T, MEMFLAGS F> HashtableEntry<T, F>* Hashtable<T, F>::new_entry(unsigned int hashValue, T obj) {
   HashtableEntry<T, F>* entry;
   entry = (HashtableEntry<T, F>*)BasicHashtable<F>::new_entry(hashValue);
   entry->set_literal(obj);
   return entry;
 }
 // Check to see if the hashtable is unbalanced.  The caller set a flag to
 // rehash at the next safepoint.  If this bucket is 60 times greater than the
 // expected average bucket length, it's an unbalanced hashtable.
 // This is somewhat an arbitrary heuristic but if one bucket gets to
 // rehash_count which is currently 100, there's probably something wrong.
 template <class T, MEMFLAGS F> bool RehashableHashtable<T, F>::check_rehash_table(int count) {
   assert(this->table_size() != 0, "underflow");
   if (count > (((double)this->number_of_entries()/(double)this->table_size())*rehash_multiple)) {
     // Set a flag for the next safepoint, which should be at some guaranteed
     // safepoint interval.
     return true;
   }
   return false;
 }
 template <class T, MEMFLAGS F> juint RehashableHashtable<T, F>::_seed = 0;
 // Create a new table and using alternate hash code, populate the new table
 // with the existing elements.   This can be used to change the hash code
 // and could in the future change the size of the table.
 template <class T, MEMFLAGS F> void RehashableHashtable<T, F>::move_to(RehashableHashtable<T, F>* new_table) {
   // Initialize the global seed for hashing.
   _seed = AltHashing::compute_seed();
   assert(seed() != 0, "shouldn't be zero");
   int saved_entry_count = this->number_of_entries();
   // Iterate through the table and create a new entry for the new table
   for (int i = 0; i < new_table->table_size(); ++i) {
     for (HashtableEntry<T, F>* p = this->bucket(i); p != NULL; ) {
       HashtableEntry<T, F>* next = p->next();
       T string = p->literal();
       // Use alternate hashing algorithm on the symbol in the first table
       unsigned int hashValue = string->new_hash(seed());
       // Get a new index relative to the new table (can also change size)
       int index = new_table->hash_to_index(hashValue);
       p->set_hash(hashValue);
       // Keep the shared bit in the Hashtable entry to indicate that this entry
       // can't be deleted.   The shared bit is the LSB in the _next field so
       // walking the hashtable past these entries requires
       // BasicHashtableEntry::make_ptr() call.
       bool keep_shared = p->is_shared();
       this->unlink_entry(p);
       new_table->add_entry(index, p);
       if (keep_shared) {
         p->set_shared();
       }
       p = next;
     }
   }
   // give the new table the free list as well
   new_table->copy_freelist(this);
   assert(new_table->number_of_entries() == saved_entry_count, "lost entry on dictionary copy?");
   // Destroy memory used by the buckets in the hashtable.  The memory
   // for the elements has been used in a new table and is not
   // destroyed.  The memory reuse will benefit resizing the SystemDictionary
   // to avoid a memory allocation spike at safepoint.
   BasicHashtable<F>::free_buckets();
 }
 template <MEMFLAGS F> void BasicHashtable<F>::free_buckets() {
   if (NULL != _buckets) {
     // Don't delete the buckets in the shared space.  They aren't
     // allocated by os::malloc
     if (!UseSharedSpaces ||
         !FileMapInfo::current_info()->is_in_shared_space(_buckets)) {
        FREE_C_HEAP_ARRAY(HashtableBucket, _buckets, F);
     }
     _buckets = NULL;
   }
 }
 // Reverse the order of elements in the hash buckets.
 template <MEMFLAGS F> void BasicHashtable<F>::reverse() {
   for (int i = 0; i < _table_size; ++i) {
     BasicHashtableEntry<F>* new_list = NULL;
     BasicHashtableEntry<F>* p = bucket(i);
     while (p != NULL) {
       BasicHashtableEntry<F>* next = p->next();
       p->set_next(new_list);
       new_list = p;
       p = next;
     }
     *bucket_addr(i) = new_list;
   }
 }
 template <MEMFLAGS F> void BasicHashtable<F>::BucketUnlinkContext::free_entry(BasicHashtableEntry<F>* entry) {
   entry->set_next(_removed_head);
   _removed_head = entry;
   if (_removed_tail == NULL) {
     _removed_tail = entry;
   }
   _num_removed++;
 }
 template <MEMFLAGS F> void BasicHashtable<F>::bulk_free_entries(BucketUnlinkContext* context) {
   if (context->_num_removed == 0) {
     assert(context->_removed_head == NULL && context->_removed_tail == NULL,
            err_msg("Zero entries in the unlink context, but elements linked from " PTR_FORMAT " to " PTR_FORMAT,
                    p2i(context->_removed_head), p2i(context->_removed_tail)));
     return;
   }
   // MT-safe add of the list of BasicHashTableEntrys from the context to the free list.
   BasicHashtableEntry<F>* current = _free_list;
   while (true) {
     context->_removed_tail->set_next(current);
     BasicHashtableEntry<F>* old = (BasicHashtableEntry<F>*)Atomic::cmpxchg_ptr(context->_removed_head, &_free_list, current);
     if (old == current) {
       break;
     }
     current = old;
   }
   Atomic::add(-context->_num_removed, &_number_of_entries);
 }
 // Copy the table to the shared space.
 template <MEMFLAGS F> void BasicHashtable<F>::copy_table(char** top, char* end) {
   // Dump the hash table entries.
   intptr_t *plen = (intptr_t*)(*top);
   *top += sizeof(*plen);
   int i;
   for (i = 0; i < _table_size; ++i) {
     for (BasicHashtableEntry<F>** p = _buckets[i].entry_addr();
                               *p != NULL;
                                p = (*p)->next_addr()) {
       if (*top + entry_size() > end) {
         report_out_of_shared_space(SharedMiscData);
       }
       *p = (BasicHashtableEntry<F>*)memcpy(*top, *p, entry_size());
       *top += entry_size();
     }
   }
   *plen = (char*)(*top) - (char*)plen - sizeof(*plen);
   // Set the shared bit.
   for (i = 0; i < _table_size; ++i) {
     for (BasicHashtableEntry<F>* p = bucket(i); p != NULL; p = p->next()) {
       p->set_shared();
     }
   }
 }
 // Reverse the order of elements in the hash buckets.
 template <class T, MEMFLAGS F> void Hashtable<T, F>::reverse(void* boundary) {
   for (int i = 0; i < this->table_size(); ++i) {
     HashtableEntry<T, F>* high_list = NULL;
     HashtableEntry<T, F>* low_list = NULL;
     HashtableEntry<T, F>* last_low_entry = NULL;
     HashtableEntry<T, F>* p = bucket(i);
     while (p != NULL) {
       HashtableEntry<T, F>* next = p->next();
       if ((void*)p->literal() >= boundary) {
         p->set_next(high_list);
         high_list = p;
       } else {
         p->set_next(low_list);
         low_list = p;
         if (last_low_entry == NULL) {
           last_low_entry = p;
         }
       }
       p = next;
     }
     if (low_list != NULL) {
       *bucket_addr(i) = low_list;
       last_low_entry->set_next(high_list);
     } else {
       *bucket_addr(i) = high_list;
     }
   }
 }
 template <class T, MEMFLAGS F> int RehashableHashtable<T, F>::literal_size(Symbol *symbol) {
   return symbol->size() * HeapWordSize;
 }
 template <class T, MEMFLAGS F> int RehashableHashtable<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 RehashableHashtable<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 = this->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(HashtableBucket<F>);
   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.
 template <MEMFLAGS F> void BasicHashtable<F>::copy_buckets(char** top, char* end) {
   intptr_t len = _table_size * sizeof(HashtableBucket<F>);
   *(intptr_t*)(*top) = len;
   *top += sizeof(intptr_t);
   *(intptr_t*)(*top) = _number_of_entries;
   *top += sizeof(intptr_t);
   if (*top + len > end) {
     report_out_of_shared_space(SharedMiscData);
   }
   _buckets = (HashtableBucket<F>*)memcpy(*top, _buckets, len);
   *top += len;
 }
 #ifndef PRODUCT
 template <class T, MEMFLAGS F> void Hashtable<T, F>::print() {
   ResourceMark rm;
   for (int i = 0; i < BasicHashtable<F>::table_size(); i++) {
     HashtableEntry<T, F>* entry = bucket(i);
     while(entry != NULL) {
       tty->print("%d : ", i);
       entry->literal()->print();
       tty->cr();
       entry = entry->next();
     }
   }
 }
 template <MEMFLAGS F> void BasicHashtable<F>::verify() {
   int count = 0;
   for (int i = 0; i < table_size(); i++) {
     for (BasicHashtableEntry<F>* p = bucket(i); p != NULL; p = p->next()) {
       ++count;
     }
   }
   assert(count == number_of_entries(), "number of hashtable entries incorrect");
 }
 #endif // PRODUCT
 #ifdef ASSERT
 template <MEMFLAGS F> void BasicHashtable<F>::verify_lookup_length(double load) {
   if ((double)_lookup_length / (double)_lookup_count > load * 2.0) {
     warning("Performance bug: SystemDictionary lookup_count=%d "
             "lookup_length=%d average=%lf load=%f",
             _lookup_count, _lookup_length,
             (double) _lookup_length / _lookup_count, load);
   }
 }
 #endif
 // Explicitly instantiate these types
 #if INCLUDE_ALL_GCS
 template class Hashtable<nmethod*, mtGC>;
 template class HashtableEntry<nmethod*, mtGC>;
 template class BasicHashtable<mtGC>;
 #endif
 template class Hashtable<ConstantPool*, mtClass>;
 template class RehashableHashtable<Symbol*, mtSymbol>;
 template class RehashableHashtable<oopDesc*, mtSymbol>;
 template class Hashtable<Symbol*, mtSymbol>;
 template class Hashtable<Klass*, mtClass>;
 template class Hashtable<oop, mtClass>;
 #if defined(SOLARIS) || defined(CHECK_UNHANDLED_OOPS)
 template class Hashtable<oop, mtSymbol>;
 template class RehashableHashtable<oop, mtSymbol>;
 #endif // SOLARIS || CHECK_UNHANDLED_OOPS
 template class Hashtable<oopDesc*, mtSymbol>;
 template class Hashtable<Symbol*, mtClass>;
 template class HashtableEntry<Symbol*, mtSymbol>;
 template class HashtableEntry<Symbol*, mtClass>;
 template class HashtableEntry<oop, mtSymbol>;
 template class BasicHashtableEntry<mtSymbol>;
 template class BasicHashtableEntry<mtCode>;
 template class BasicHashtable<mtClass>;
 template class BasicHashtable<mtSymbol>;
 template class BasicHashtable<mtCode>;
 template class BasicHashtable<mtInternal>;

Mercurial > jdk8-mips64-public > hotspot / annotate

src/share/vm/utilities/hashtable.cpp@ce9a710b0f63 (annotated)

src/share/vm/utilities/hashtable.cpp