diff --git a/.gitmodules b/.gitmodules
index 30ef58db1..df60ddab7 100644
--- a/.gitmodules
+++ b/.gitmodules
@@ -14,3 +14,6 @@
 [submodule "tests/plugins/PocketMine-DevTools"]
 	path = tests/plugins/PocketMine-DevTools
 	url = https://github.com/pmmp/PocketMine-DevTools.git
+[submodule "tests/plugins/PocketMine-TesterPlugin"]
+	path = tests/plugins/PocketMine-TesterPlugin
+	url = https://github.com/pmmp/PocketMine-TesterPlugin.git
diff --git a/src/pocketmine/PocketMine.php b/src/pocketmine/PocketMine.php
index d39ceab3b..819df2399 100644
--- a/src/pocketmine/PocketMine.php
+++ b/src/pocketmine/PocketMine.php
@@ -234,7 +234,6 @@ namespace pocketmine {
 				}
 
 				return parse_offset($offset);
-				break;
 			case 'linux':
 				// Ubuntu / Debian.
 				if(file_exists('/etc/timezone')){
@@ -261,7 +260,6 @@ namespace pocketmine {
 				}
 
 				return parse_offset($offset);
-				break;
 			case 'mac':
 				if(is_link('/etc/localtime')){
 					$filename = readlink('/etc/localtime');
@@ -272,10 +270,8 @@ namespace pocketmine {
 				}
 
 				return false;
-				break;
 			default:
 				return false;
-				break;
 		}
 	}
 
diff --git a/src/pocketmine/scheduler/AsyncPool.php b/src/pocketmine/scheduler/AsyncPool.php
index 22433690c..638169e00 100644
--- a/src/pocketmine/scheduler/AsyncPool.php
+++ b/src/pocketmine/scheduler/AsyncPool.php
@@ -136,6 +136,14 @@ class AsyncPool{
 
 		$this->taskWorkers = [];
 		$this->tasks = [];
+
+		$this->collectWorkers();
+	}
+
+	private function collectWorkers(){
+		foreach($this->workers as $worker){
+			$worker->collect();
+		}
 	}
 
 	public function collectTasks(){
@@ -158,6 +166,8 @@ class AsyncPool{
 			}
 		}
 
+		$this->collectWorkers();
+
 		Timings::$schedulerAsyncTimer->stopTiming();
 	}
 }
diff --git a/src/pocketmine/scheduler/AsyncTask.php b/src/pocketmine/scheduler/AsyncTask.php
index 68491511c..cd50ac11e 100644
--- a/src/pocketmine/scheduler/AsyncTask.php
+++ b/src/pocketmine/scheduler/AsyncTask.php
@@ -261,7 +261,8 @@ abstract class AsyncTask extends Collectable{
 				$this->{$p} = null;
 			}
 		}
-	}
 
+		$this->setGarbage();
+	}
 }
 
diff --git a/tests/plugins/PocketMine-TesterPlugin b/tests/plugins/PocketMine-TesterPlugin
new file mode 160000
index 000000000..a282b45c1
--- /dev/null
+++ b/tests/plugins/PocketMine-TesterPlugin
@@ -0,0 +1 @@
+Subproject commit a282b45c1d9d2108d602ccb5df7fdef4ef364232
diff --git a/tests/travis.sh b/tests/travis.sh
index 4f53ec0a6..d57da86a1 100755
--- a/tests/travis.sh
+++ b/tests/travis.sh
@@ -17,7 +17,11 @@ if [ $? -ne 0 ]; then
 	exit 1
 fi
 
-cp -r tests/plugins plugins
+rm server.log 2> /dev/null
+mkdir -p ./plugins
+
+cp -r tests/plugins/PocketMine-DevTools ./plugins
+
 "$PHP_BINARY" ./plugins/PocketMine-DevTools/src/DevTools/ConsoleScript.php --make ./plugins/PocketMine-DevTools --relative ./plugins/PocketMine-DevTools --out ./plugins/DevTools.phar
 rm -rf ./plugins/PocketMine-DevTools
 
@@ -28,3 +32,15 @@ else
     echo No phar created!
     exit 1
 fi
+
+cp -r tests/plugins/PocketMine-TesterPlugin ./plugins
+"$PHP_BINARY" src/pocketmine/PocketMine.php --no-wizard --disable-ansi --disable-readline --debug.level=2
+
+result=$(grep 'TesterPlugin' server.log | grep 'Finished' | grep -v 'PASS')
+if [ "$result" != "" ]; then
+   echo "$result"
+   echo Some tests did not complete successfully, changing build status to failed
+   exit 1
+else
+    echo All tests passed
+fi