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: [PATCH] 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(-)

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();