From 4ddf3385a84c69c9b6262f5226d02cad153976c5 Mon Sep 17 00:00:00 2001
From: Kao Makino <kao.makino@snowflake.com>
Date: Tue, 19 Jan 2021 17:13:27 -0800
Subject: [PATCH] Reserve the priority queue container

---
 flow/Knobs.cpp      |  1 +
 flow/Knobs.h        |  1 +
 flow/Net2.actor.cpp | 13 ++++++++++++-
 3 files changed, 14 insertions(+), 1 deletion(-)

diff --git a/flow/Knobs.cpp b/flow/Knobs.cpp
index 28b7deb180..da722d2079 100644
--- a/flow/Knobs.cpp
+++ b/flow/Knobs.cpp
@@ -122,6 +122,7 @@ FlowKnobs::FlowKnobs(bool randomize, bool isSimulated) {
 	init( SLOW_LOOP_SAMPLING_RATE,                             0.1 );
 	init( TSC_YIELD_TIME,                                  1000000 );
 	init( CERT_FILE_MAX_SIZE,                      5 * 1024 * 1024 );
+	init( READY_QUEUE_RESERVED_SIZE,                          8192 );
 
 	//Network
 	init( PACKET_LIMIT,                                  100LL<<20 );
diff --git a/flow/Knobs.h b/flow/Knobs.h
index 5dd746cc84..258ea28ea2 100644
--- a/flow/Knobs.h
+++ b/flow/Knobs.h
@@ -143,6 +143,7 @@ public:
 	int64_t TSC_YIELD_TIME;
 	int64_t REACTOR_FLAGS;
 	int CERT_FILE_MAX_SIZE;
+	int READY_QUEUE_RESERVED_SIZE;
 
 	//Network
 	int64_t PACKET_LIMIT;
diff --git a/flow/Net2.actor.cpp b/flow/Net2.actor.cpp
index c77078dfcb..5ffa5f250b 100644
--- a/flow/Net2.actor.cpp
+++ b/flow/Net2.actor.cpp
@@ -111,6 +111,16 @@ struct OrderedTask {
 	bool operator < (OrderedTask const& rhs) const { return priority < rhs.priority; }
 };
 
+template <class T>
+class ReadyQueue : public std::priority_queue<T, std::vector<T>>
+{
+public:
+	typedef typename std::priority_queue<T, std::vector<T>>::size_type size_type;
+	ReadyQueue(size_type capacity = 0) { reserve(capacity); };
+	void reserve(size_type capacity) { this->c.reserve(capacity); } 
+};
+
+
 thread_local INetwork* thread_network = 0;
 
 class Net2 sealed : public INetwork, public INetworkConnections {
@@ -190,7 +200,7 @@ public:
 
 	TaskPriority lastMinTaskID;
 
-	std::priority_queue<OrderedTask, std::vector<OrderedTask>> ready;
+	ReadyQueue<OrderedTask> ready;
 	ThreadSafeQueue<OrderedTask> threadReady;
 
 	struct DelayedTask : OrderedTask {
@@ -843,6 +853,7 @@ Net2::Net2(const TLSConfig& tlsConfig, bool useThreadPool, bool useMetrics)
 	  reactor(this),
 	  stopped(false),
 	  tasksIssued(0),
+	  ready(FLOW_KNOBS->READY_QUEUE_RESERVED_SIZE),
 	  // Until run() is called, yield() will always yield
 	  tsc_begin(0), tsc_end(0), taskBegin(0), currentTaskID(TaskPriority::DefaultYield),
 	  lastMinTaskID(TaskPriority::Zero),