--- /dev/null	2019-06-28 15:24:43.000000000 -0700
+++ new/src/hotspot/share/services/threadTable.cpp	2019-06-28 15:24:43.000000000 -0700
@@ -0,0 +1,221 @@
+
+/*
+* Copyright (c) 2019, 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 "runtime/interfaceSupport.inline.hpp"
+#include "runtime/timerTrace.hpp"
+#include "runtime/thread.hpp"
+#include "services/threadTable.hpp"
+#include "utilities/concurrentHashTable.inline.hpp"
+#include "utilities/concurrentHashTableTasks.inline.hpp"
+
+
+// 2^24 is max size
+static const size_t END_SIZE = 24;
+// Initial size 256
+static const size_t ThreadTableSizeLog = 8;
+// Prefer short chains of avg 2
+static const double PREF_AVG_LIST_LEN = 2.0;
+
+typedef ConcurrentHashTable<ThreadTableConfig, mtInternal> ThreadTableHash;
+
+static ThreadTableHash* _local_table = NULL;
+
+volatile bool ThreadTable::_has_work = false;
+
+static volatile size_t _current_size = 0;
+static volatile size_t _items_count = 0;
+
+
+class ThreadTableEntry : public CHeapObj<mtInternal> {
+  private:
+    jlong _tid;
+    JavaThread* _java_thread;
+  public:
+    ThreadTableEntry(jlong tid, JavaThread* java_thread) :
+    _tid(tid),_java_thread(java_thread) {}
+
+    jlong tid() const { return _tid;}
+    JavaThread* thread() const {return _java_thread;}
+};
+
+class ThreadTableConfig : public AllStatic {
+  public:
+    typedef ThreadTableEntry* Value;
+
+    static uintx get_hash(Value const& value, bool* is_dead) {
+        *is_dead = false;
+        jlong tid = value->tid();
+        return primitive_hash(tid);
+    }
+    static void* allocate_node(size_t size, Value const& value) {
+        ThreadTable::item_added();
+        return AllocateHeap(size, mtInternal);
+    }
+    static void free_node(void* memory, Value const& value) {
+        delete value;
+        FreeHeap(memory);
+        ThreadTable::item_removed();
+    }
+};
+
+void ThreadTable::create_table() {
+    _current_size = (size_t)1 << ThreadTableSizeLog;
+    _local_table = new ThreadTableHash(ThreadTableSizeLog, END_SIZE);
+}
+
+void ThreadTable::item_added() {
+    Atomic::inc(&_items_count);
+    log_trace(thread, table) ("Thread entry added");
+}
+
+void ThreadTable::item_removed() {
+    Atomic::dec(&_items_count);
+    log_trace(thread, table) ("Thread entry removed");
+}
+
+double ThreadTable::get_load_factor() {
+    return (double)_items_count/_current_size;
+}
+
+size_t ThreadTable::table_size() {
+    return (size_t)1 << _local_table->get_size_log2(Thread::current());
+}
+
+void ThreadTable::check_concurrent_work() {
+    if (_has_work) {
+        return;
+    }
+    
+    double load_factor = get_load_factor();
+    // Resize if we have more items than preferred load factor
+    if ( load_factor > PREF_AVG_LIST_LEN) {
+        log_debug(thread, table)("Concurrent work triggered, load factor: %g",
+                                     load_factor);
+        trigger_concurrent_work();
+    }
+}
+
+void ThreadTable::trigger_concurrent_work() {
+    MutexLocker ml(Service_lock, Mutex::_no_safepoint_check_flag);
+    _has_work = true;
+    Service_lock->notify_all();
+}
+
+void ThreadTable::do_concurrent_work(JavaThread* jt) {
+    _has_work = false;
+    double load_factor = get_load_factor();
+    log_debug(thread, table)("Concurrent work, load factor: %g", load_factor);
+    if (load_factor > PREF_AVG_LIST_LEN && !_local_table->is_max_size_reached()) {
+        grow(jt);
+    }
+}
+
+void ThreadTable::grow(JavaThread* jt) {
+    ThreadTableHash::GrowTask gt(_local_table);
+    if (!gt.prepare(jt)) {
+        return;
+    }
+    log_trace(thread, table)("Started to grow");
+    {
+        TraceTime timer("Grow", TRACETIME_LOG(Debug, membername, table, perf));
+        while (gt.do_task(jt)) {
+            gt.pause(jt);
+            {
+                ThreadBlockInVM tbivm(jt);
+            }
+            gt.cont(jt);
+        }
+    }
+    gt.done(jt);
+    _current_size = table_size();
+    log_info(thread, table)("Grown to size:" SIZE_FORMAT, _current_size);
+}
+
+class ThreadTableLookup : public StackObj {
+  private:
+    jlong          _tid;
+    uintx         _hash;
+  public:
+    ThreadTableLookup(jlong tid)
+    : _tid(tid), _hash(primitive_hash(tid)) {}
+    uintx get_hash() const {
+        return _hash;
+    }
+    bool equals(ThreadTableEntry **value, bool* is_dead) {
+        *is_dead = false;
+        bool equals = primitive_equals(_tid, (*value)->tid());
+        if (!equals) {
+            return false;
+        }
+        return true;
+    }
+};
+
+class ThreadGet : public StackObj {
+  private:
+    JavaThread* _return;
+  public:
+    ThreadGet():_return(NULL) {}
+    void operator()(ThreadTableEntry** val) {
+        _return = (*val)->thread();
+    }
+    JavaThread* get_res_thread() {
+        return _return;
+    }
+};
+
+JavaThread* ThreadTable::find_thread(jlong tid) {
+    Thread* thread = Thread::current();
+    ThreadTableLookup lookup(tid);
+    ThreadGet tg;
+    _local_table->get(thread, lookup, tg);
+    return tg.get_res_thread();
+}
+
+
+JavaThread* ThreadTable::add_thread(jlong tid, JavaThread* java_thread) {
+    Thread* thread = Thread::current();
+    ThreadTableLookup lookup(tid);
+    ThreadGet tg;
+    while(true) {
+        if (_local_table->get(thread, lookup, tg)) {
+            return tg.get_res_thread();
+        }
+        ThreadTableEntry* entry = new ThreadTableEntry(tid,java_thread);
+        // The hash table takes ownership of the ThreadTableEntry,
+        // even if it's not inserted.
+        if (_local_table->insert(thread, lookup, entry)) {
+            check_concurrent_work();
+            return java_thread;
+        }
+    }
+}
+
+bool ThreadTable::remove_thread(jlong tid) {
+    Thread* thread = Thread::current();
+    ThreadTableLookup lookup(tid);
+    return _local_table->remove(thread,lookup);
+}