* Update Hdr

* lazy vals in Kamon in order to avoid weird race conditions on startup

Author: dpsoft

build.sbt

@@ -20,10 +20,10 @@ lazy val kamon = (project in file("."))
   .aggregate(core, testkit, coreTests)
 
 val commonSettings = Seq(
-  scalaVersion := "2.12.4",
+  scalaVersion := "2.12.8",
   javacOptions += "-XDignore.symbol.file",
   resolvers += Resolver.mavenLocal,
-  crossScalaVersions := Seq("2.12.4", "2.11.8", "2.10.6"),
+  crossScalaVersions := Seq("2.12.8", "2.11.12", "2.10.7"),
   concurrentRestrictions in Global += Tags.limit(Tags.Test, 1),
   scalacOptions ++= Seq(
     "-deprecation",
@@ -47,7 +47,7 @@ lazy val core = (project in file("kamon-core"))
     libraryDependencies ++= Seq(
       "com.typesafe"     %  "config"          % "1.3.1",
       "org.slf4j"        %  "slf4j-api"       % "1.7.25",
-      "org.hdrhistogram" %  "HdrHistogram"    % "2.1.9",
+      "org.hdrhistogram" %  "HdrHistogram"    % "2.1.11",
       "com.lihaoyi"      %% "fansi"           % "0.2.4"
     )
   )

kamon-core/src/main/scala/kamon/Kamon.scala

@@ -1,5 +1,5 @@
 /* =========================================================================================
- * Copyright © 2013-2017 the kamon project <http://kamon.io/>
+ * Copyright © 2013-2019 the kamon project <http://kamon.io/>
  *
  * Licensed under the Apache License, Version 2.0 (the "License"); you may not use this file
  * except in compliance with the License. You may obtain a copy of the License at
@@ -36,13 +36,13 @@ object Kamon extends MetricLookup with ReporterRegistry with Tracer {
   @volatile private var _environment = Environment.fromConfig(_config)
   @volatile private var _filters = Filters.fromConfig(_config)
 
-  private val _clock = new Clock.Default()
-  private val _scheduler = Executors.newScheduledThreadPool(schedulerPoolSize(_config), numberedThreadFactory("kamon-scheduler", daemon = true))
-  private val _metrics = new MetricRegistry(_config, _scheduler)
-  private val _reporterRegistry = new ReporterRegistry.Default(_metrics, _config, _clock)
-  private val _tracer = Tracer.Default(Kamon, _reporterRegistry, _config, _clock)
-  private val _contextStorage = Storage.ThreadLocal()
-  private val _contextCodec = new Codecs(_config)
+  private lazy val _clock = new Clock.Default()
+  private lazy val _scheduler = Executors.newScheduledThreadPool(schedulerPoolSize(_config), numberedThreadFactory("kamon-scheduler", daemon = true))
+  private lazy val _metrics = new MetricRegistry(_config, _scheduler)
+  private lazy val _reporterRegistry = new ReporterRegistry.Default(_metrics, _config, _clock)
+  private lazy val _tracer = Tracer.Default(Kamon, _reporterRegistry, _config, _clock)
+  private lazy val _contextStorage = Storage.ThreadLocal()
+  private lazy val _contextCodec = new Codecs(_config)
   private var _onReconfigureHooks = Seq.empty[OnReconfigureHook]
 
   sys.addShutdownHook(() => _scheduler.shutdown())