From 99a5b882d8cfaba6ed18966e893ce70ac3c81fde Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?S=C3=B6nke=20Ludwig?= <sludwig@rejectedsoftware.com>
Date: Tue, 30 May 2017 11:00:37 +0200
Subject: [PATCH] Limit the number of recycled fibers.

This allows the process to free up memory after heavy load spikes, while not impacting performance negatively.
---
 source/vibe/core/core.d | 15 +++++++++++++--
 source/vibe/core/task.d | 15 +++++++++++++++
 2 files changed, 28 insertions(+), 2 deletions(-)

diff --git a/source/vibe/core/core.d b/source/vibe/core/core.d
index 4f9c0d6..d43f6e3 100644
--- a/source/vibe/core/core.d
+++ b/source/vibe/core/core.d
@@ -1,7 +1,7 @@
 /**
 	This module contains the core functionality of the vibe.d framework.
 
-	Copyright: © 2012-2016 RejectedSoftware e.K.
+	Copyright: © 2012-2017 RejectedSoftware e.K.
 	License: Subject to the terms of the MIT license, as written in the included LICENSE.txt file.
 	Authors: Sönke Ludwig
 */
@@ -763,7 +763,7 @@ unittest {
 }
 
 /// Compatibility overload - use a `@safe nothrow` callback instead.
-deprecated("Use anothrow callback as argument to setTimer.")
+deprecated("Use an @safe nothrow callback as argument to setTimer.")
 Timer setTimer(Duration timeout, void delegate() callback, bool periodic = false)
 @safe nothrow {
 	return setTimer(timeout, () @trusted nothrow {
@@ -1108,6 +1108,7 @@ private {
 
 	TaskScheduler s_scheduler;
 	FixedRingBuffer!TaskFiber s_availableFibers;
+	size_t s_maxRecycledFibers = 100;
 
 	string s_privilegeLoweringUserName;
 	string s_privilegeLoweringGroupName;
@@ -1124,6 +1125,16 @@ package @property ref TaskScheduler taskScheduler() @safe nothrow @nogc { return
 
 package void recycleFiber(TaskFiber fiber)
 @safe nothrow {
+	if (s_availableFibers.length >= s_maxRecycledFibers) {
+		auto fl = s_availableFibers.front;
+		s_availableFibers.popFront();
+		fl.shutdown();
+		() @trusted {
+			try destroy(fl);
+			catch (Exception e) logWarn("Failed to destroy fiber: %s", e.msg);
+		} ();
+	}
+
 	if (s_availableFibers.full)
 		s_availableFibers.capacity = 2 * s_availableFibers.capacity;
 
diff --git a/source/vibe/core/task.d b/source/vibe/core/task.d
index 584dc5b..44c5067 100644
--- a/source/vibe/core/task.d
+++ b/source/vibe/core/task.d
@@ -293,6 +293,7 @@ final package class TaskFiber : Fiber {
 		ThreadInfo m_tidInfo;
 		shared size_t m_taskCounter;
 		shared bool m_running;
+		bool m_shutdown = false;
 
 		shared(ManualEvent) m_onExit;
 
@@ -352,6 +353,7 @@ final package class TaskFiber : Fiber {
 						logWarn("CoreTaskFiber was resumed with exception but without active task!");
 						logDiagnostic("Full error: %s", e.toString().sanitize());
 					}
+					if (m_shutdown) return;
 				}
 
 				TaskFuncInfo task;
@@ -431,6 +433,19 @@ final package class TaskFiber : Fiber {
 
 	@property size_t taskCounter() const @safe nothrow { return m_taskCounter; }
 
+	/** Shuts down the task handler loop.
+	*/
+	void shutdown()
+	@safe nothrow {
+		assert(!m_running);
+		m_shutdown = true;
+		while (state != Fiber.State.TERM)
+			() @trusted {
+				try call(Fiber.Rethrow.no);
+				catch (Exception e) assert(false, e.msg);
+			} ();
+	}
+
 	/** Blocks until the task has ended.
 	*/
 	void join(bool interruptiple)(size_t task_counter)