From 510d0d47537aea8eff2e9c855099c4d4839cef32 Mon Sep 17 00:00:00 2001
From: Howard Chu <hyc@symas.com>
Date: Thu, 14 Sep 2017 04:39:37 +0100
Subject: Use a threadpool

Instead of constantly creating and destroying threads
---
 src/common/threadpool.cpp | 113 ++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 113 insertions(+)
 create mode 100644 src/common/threadpool.cpp

(limited to 'src/common/threadpool.cpp')

diff --git a/src/common/threadpool.cpp b/src/common/threadpool.cpp
new file mode 100644
index 000000000..f7f9bbbaf
--- /dev/null
+++ b/src/common/threadpool.cpp
@@ -0,0 +1,113 @@
+// Copyright (c) 2017, The Monero Project
+//
+// All rights reserved.
+//
+// Redistribution and use in source and binary forms, with or without modification, are
+// permitted provided that the following conditions are met:
+//
+// 1. Redistributions of source code must retain the above copyright notice, this list of
+//    conditions and the following disclaimer.
+//
+// 2. Redistributions in binary form must reproduce the above copyright notice, this list
+//    of conditions and the following disclaimer in the documentation and/or other
+//    materials provided with the distribution.
+//
+// 3. Neither the name of the copyright holder nor the names of its contributors may be
+//    used to endorse or promote products derived from this software without specific
+//    prior written permission.
+//
+// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" AND ANY
+// EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF
+// MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL
+// THE COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+// SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
+// PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
+// INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT,
+// STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF
+// THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+#include "common/threadpool.h"
+
+#include <cassert>
+#include <limits>
+#include <stdexcept>
+
+#include "cryptonote_config.h"
+#include "common/util.h"
+
+namespace tools
+{
+threadpool::threadpool() : running(true), active(0) {
+  boost::thread::attributes attrs;
+  attrs.set_stack_size(THREAD_STACK_SIZE);
+  max = tools::get_max_concurrency();
+  size_t i = max;
+  while(i--) {
+    threads.push_back(boost::thread(attrs, boost::bind(&threadpool::run, this)));
+  }
+}
+
+threadpool::~threadpool() {
+  {
+    const boost::unique_lock<boost::mutex> lock(mutex);
+    running = false;
+    has_work.notify_all();
+  }
+  for (size_t i = 0; i<threads.size(); i++) {
+    threads[i].join();
+  }
+}
+
+void threadpool::submit(waiter *obj, std::function<void()> f) {
+  entry e = {obj, f};
+  boost::unique_lock<boost::mutex> lock(mutex);
+  if (active == max && !queue.empty()) {
+    // if all available threads are already running
+    // and there's work waiting, just run in current thread
+    lock.unlock();
+    f();
+  } else {
+    if (obj)
+      obj->inc();
+    queue.push_back(e);
+    has_work.notify_one();
+  }
+}
+
+void threadpool::waiter::wait() {
+  boost::unique_lock<boost::mutex> lock(mt);
+  while(num) cv.wait(lock);
+}
+
+void threadpool::waiter::inc() {
+  const boost::unique_lock<boost::mutex> lock(mt);
+  num++;
+}
+
+void threadpool::waiter::dec() {
+  const boost::unique_lock<boost::mutex> lock(mt);
+  num--;
+  if (!num)
+    cv.notify_one();
+}
+
+void threadpool::run() {
+  boost::unique_lock<boost::mutex> lock(mutex);
+  while (running) {
+    entry e;
+    while(queue.empty() && running)
+      has_work.wait(lock);
+    if (!running) break;
+
+    active++;
+    e = queue.front();
+    queue.pop_front();
+    lock.unlock();
+    e.f();
+
+    if (e.wo)
+      e.wo->dec();
+    lock.lock();
+    active--;
+  }
+}
+}
-- 
cgit v1.2.3


From 6d0ca7d11f18d1d842ec1ac639da4309ae41a83f Mon Sep 17 00:00:00 2001
From: Howard Chu <hyc@symas.com>
Date: Fri, 15 Sep 2017 00:28:48 +0100
Subject: Tweak concurrency limits

Create capacity for 2x max, but lie about it
---
 src/common/threadpool.cpp | 6 +++++-
 src/common/threadpool.h   | 2 +-
 2 files changed, 6 insertions(+), 2 deletions(-)

(limited to 'src/common/threadpool.cpp')

diff --git a/src/common/threadpool.cpp b/src/common/threadpool.cpp
index f7f9bbbaf..41d0c25e0 100644
--- a/src/common/threadpool.cpp
+++ b/src/common/threadpool.cpp
@@ -39,7 +39,7 @@ namespace tools
 threadpool::threadpool() : running(true), active(0) {
   boost::thread::attributes attrs;
   attrs.set_stack_size(THREAD_STACK_SIZE);
-  max = tools::get_max_concurrency();
+  max = tools::get_max_concurrency() * 2;
   size_t i = max;
   while(i--) {
     threads.push_back(boost::thread(attrs, boost::bind(&threadpool::run, this)));
@@ -73,6 +73,10 @@ void threadpool::submit(waiter *obj, std::function<void()> f) {
   }
 }
 
+int threadpool::get_max_concurrency() {
+  return max / 2;
+}
+
 void threadpool::waiter::wait() {
   boost::unique_lock<boost::mutex> lock(mt);
   while(num) cv.wait(lock);
diff --git a/src/common/threadpool.h b/src/common/threadpool.h
index 9455e9f66..1d56d7605 100644
--- a/src/common/threadpool.h
+++ b/src/common/threadpool.h
@@ -65,7 +65,7 @@ public:
   // task to finish.
   void submit(waiter *waiter, std::function<void()> f);
 
-  int get_max_concurrency() { return max; }
+  int get_max_concurrency();
 
   private:
     threadpool();
-- 
cgit v1.2.3