1 

     2 /*

     3 * Copyright (c) 2019, Oracle and/or its affiliates. All rights reserved.

     4 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.

     5 *

     6 * This code is free software; you can redistribute it and/or modify it

     7 * under the terms of the GNU General Public License version 2 only, as

     8 * published by the Free Software Foundation.

     9 *

    10 * This code is distributed in the hope that it will be useful, but WITHOUT

    11 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or

    12 * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License

    13 * version 2 for more details (a copy is included in the LICENSE file that

    14 * accompanied this code).

    15 *

    16 * You should have received a copy of the GNU General Public License version

    17 * 2 along with this work; if not, write to the Free Software Foundation,

    18 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.

    19 *

    20 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA

    21 * or visit www.oracle.com if you need additional information or have any

    22 * questions.

    23 *

    24 */

    25 

    26 #include "precompiled.hpp"

    27 #include "runtime/interfaceSupport.inline.hpp"

    28 #include "runtime/thread.hpp"

    29 #include "runtime/threadSMR.hpp"

    30 #include "runtime/timerTrace.hpp"

    31 #include "services/threadIdTable.hpp"

    32 #include "utilities/concurrentHashTable.inline.hpp"

    33 #include "utilities/concurrentHashTableTasks.inline.hpp"

    34 

    35 

    36 typedef ConcurrentHashTable<ThreadIdTableConfig, mtInternal> ThreadIdTableHash;

    37 

    38 // 2^24 is max size

    39 static const size_t END_SIZE = 24;

    40 // Default initial size 256

    41 static const size_t DEFAULT_TABLE_SIZE_LOG = 8;

    42 // Prefer short chains of avg 2

    43 static const double PREF_AVG_LIST_LEN = 2.0;

    44 static ThreadIdTableHash* volatile _local_table = NULL;

    45 static volatile size_t _current_size = 0;

    46 static volatile size_t _items_count = 0;

    47 

    48 volatile bool ThreadIdTable::_is_initialized = false;

    49 

    50 class ThreadIdTableEntry : public CHeapObj<mtInternal> {

    51 private:

    52   jlong _tid;

    53   JavaThread* _java_thread;

    54 public:

    55   ThreadIdTableEntry(jlong tid, JavaThread* java_thread) :

    56     _tid(tid), _java_thread(java_thread) {}

    57 

    58   jlong tid() const { return _tid; }

    59   JavaThread* thread() const { return _java_thread; }

    60 };

    61 

    62 class ThreadIdTableConfig : public AllStatic {

    63   public:

    64     typedef ThreadIdTableEntry* Value;

    65 

    66     static uintx get_hash(Value const& value, bool* is_dead) {

    67       jlong tid = value->tid();

    68       return primitive_hash(tid);

    69     }

    70     static void* allocate_node(size_t size, Value const& value) {

    71       ThreadIdTable::item_added();

    72       return AllocateHeap(size, mtInternal);

    73     }

    74     static void free_node(void* memory, Value const& value) {

    75       delete value;

    76       FreeHeap(memory);

    77       ThreadIdTable::item_removed();

    78     }

    79 };

    80 

    81 static size_t ceil_log2(size_t val) {

    82   size_t ret;

    83   for (ret = 1; ((size_t)1 << ret) < val; ++ret);

    84   return ret;

    85 }

    86 

    87 // Lazily creates the table and populates it with the given

    88 // thread list

    89 void ThreadIdTable::lazy_initialize(const ThreadsList *threads) {

    90   if (!_is_initialized) {

    91     {

    92       // There is no obvious benefits in allowing the thread table

    93       // to be concurently populated during the initalization.

    94       MutexLocker ml(ThreadIdTableCreate_lock);

    95       if (_is_initialized) {

    96         return;

    97       }

    98       create_table(threads->length());

    99       _is_initialized = true;

   100     }

   101     for (uint i = 0; i < threads->length(); i++) {

   102       JavaThread* thread = threads->thread_at(i);

   103       oop tobj = thread->threadObj();

   104       if (tobj != NULL) {

   105         jlong java_tid = java_lang_Thread::thread_id(tobj);

   106         MutexLocker ml(Threads_lock);

   107         if (!thread->is_exiting()) {

   108           // Must be inside the lock to ensure that we don't add a thread to the table

   109           // that has just passed the removal point in ThreadsSMRSupport::remove_thread()

   110           add_thread(java_tid, thread);

   111         }

   112       }

   113     }

   114   }

   115 }

   116 

   117 void ThreadIdTable::create_table(size_t size) {

   118   assert(_local_table == NULL, "Thread table is already created");

   119   size_t size_log = ceil_log2(size);

   120   size_t start_size_log =

   121       size_log > DEFAULT_TABLE_SIZE_LOG ? size_log : DEFAULT_TABLE_SIZE_LOG;

   122   _current_size = (size_t)1 << start_size_log;

   123   _local_table = new ThreadIdTableHash(start_size_log, END_SIZE);

   124 }

   125 

   126 void ThreadIdTable::item_added() {

   127   Atomic::inc(&_items_count);

   128   log_trace(thread, table) ("Thread entry added");

   129 }

   130 

   131 void ThreadIdTable::item_removed() {

   132   Atomic::dec(&_items_count);

   133   log_trace(thread, table) ("Thread entry removed");

   134 }

   135 

   136 double ThreadIdTable::get_load_factor() {

   137   return ((double)_items_count) / _current_size;

   138 }

   139 

   140 size_t ThreadIdTable::table_size() {

   141   return (size_t)1 << _local_table->get_size_log2(Thread::current());

   142 }

   143 

   144 void ThreadIdTable::grow(JavaThread* jt) {

   145   ThreadIdTableHash::GrowTask gt(_local_table);

   146   if (!gt.prepare(jt)) {

   147     return;

   148   }

   149   log_trace(thread, table)("Started to grow");

   150   TraceTime timer("Grow", TRACETIME_LOG(Debug, membername, table, perf));

   151   while (gt.do_task(jt)) {

   152     gt.pause(jt);

   153     {

   154       ThreadBlockInVM tbivm(jt);

   155     }

   156     gt.cont(jt);

   157   }

   158   gt.done(jt);

   159   _current_size = table_size();

   160   log_info(thread, table)("Grown to size:" SIZE_FORMAT, _current_size);

   161 }

   162 

   163 class ThreadIdTableLookup : public StackObj {

   164 private:

   165   jlong _tid;

   166   uintx _hash;

   167 public:

   168   ThreadIdTableLookup(jlong tid)

   169     : _tid(tid), _hash(primitive_hash(tid)) {}

   170   uintx get_hash() const {

   171     return _hash;

   172   }

   173   bool equals(ThreadIdTableEntry** value, bool* is_dead) {

   174     bool equals = primitive_equals(_tid, (*value)->tid());

   175     if (!equals) {

   176       return false;

   177     }

   178     return true;

   179   }

   180 };

   181 

   182 class ThreadGet : public StackObj {

   183 private:

   184   JavaThread* _return;

   185 public:

   186   ThreadGet(): _return(NULL) {}

   187   void operator()(ThreadIdTableEntry** val) {

   188     _return = (*val)->thread();

   189   }

   190   JavaThread* get_res_thread() {

   191     return _return;

   192   }

   193 };

   194 

   195 void ThreadIdTable::grow_if_required() {

   196   assert(Thread::current()->is_Java_thread(),"Must be Java thread");

   197   assert(_is_initialized, "Thread table is not initialized");

   198   double load_factor = get_load_factor();

   199   log_debug(thread, table)("Concurrent work, load factor: %g", load_factor);

   200   if (load_factor > PREF_AVG_LIST_LEN && !_local_table->is_max_size_reached()) {

   201     grow(JavaThread::current());

   202   }

   203 }

   204 

   205 JavaThread* ThreadIdTable::add_thread(jlong tid, JavaThread* java_thread) {

   206   assert(_is_initialized, "Thread table is not initialized");

   207   Thread* thread = Thread::current();

   208   ThreadIdTableLookup lookup(tid);

   209   ThreadGet tg;

   210   while (true) {

   211     if (_local_table->get(thread, lookup, tg)) {

   212       return tg.get_res_thread();

   213     }

   214     ThreadIdTableEntry* entry = new ThreadIdTableEntry(tid, java_thread);

   215     // The hash table takes ownership of the ThreadTableEntry,

   216     // even if it's not inserted.

   217     if (_local_table->insert(thread, lookup, entry)) {

   218       grow_if_required();

   219       return java_thread;

   220     }

   221   }

   222 }

   223 

   224 JavaThread* ThreadIdTable::find_thread_by_tid(jlong tid) {

   225   assert(_is_initialized, "Thread table is not initialized");

   226   Thread* thread = Thread::current();

   227   ThreadIdTableLookup lookup(tid);

   228   ThreadGet tg;

   229   _local_table->get(thread, lookup, tg);

   230   return tg.get_res_thread();

   231 }

   232 

   233 bool ThreadIdTable::remove_thread(jlong tid) {

   234   assert(_is_initialized, "Thread table is not initialized");

   235   Thread* thread = Thread::current();

   236   ThreadIdTableLookup lookup(tid);

   237   return _local_table->remove(thread, lookup);

   238 }