--- old/test/hotspot/jtreg/gc/stress/systemgc/TestSystemGC.java	2017-11-07 10:10:44.071317913 +0100
+++ new/test/hotspot/jtreg/gc/stress/systemgc/TestSystemGC.java	2017-11-07 10:10:43.658305226 +0100
@@ -90,7 +90,6 @@
     private long delayMS;
 
     SystemGCTask(long delayMS) {
-System.err.println("SystemGCTask with delay " + delayMS);
         this.delayMS = delayMS;
     }
 
@@ -98,7 +97,7 @@
     public void run() {
         while (!shouldExit()) {
             System.gc();
-            ThreadUtils.sleep(delayMS * 10);
+            ThreadUtils.sleep(delayMS);
         }
     }
 }
@@ -165,8 +164,7 @@
     }
 
     private static void runAllPhases() {
-        int i = 0;
-        while (i < 4 && System.currentTimeMillis() < endTime) {
+        for (int i = 0; i < 4 && System.currentTimeMillis() < endTime; i++) {
             SystemGCTask gcTask =
                 (i % 2 == 1) ? createSystemGCTask(numGroups / 3) : null;
             ShortLivedAllocationTask shortTask =
@@ -185,16 +183,16 @@
             exitTask(longTask);
 
             ThreadUtils.sleep(1000);
-            i++;
         }
     }
 
-    public static void main(String[] args) {
-        if (args.length > 0) {
-            int timeout = Integer.parseInt(args[0]) * 1000;
-            System.out.println("Running with timeout of " + timeout + "ms");
-            endTime = System.currentTimeMillis() + timeout;
-        }
+    public static void main(String[] args) throws Exception {
+        if (args.length == 0) {
+            throw new IllegalArgumentException("Must specify timeout in seconds as first argument");
+        }
+        int timeout = Integer.parseInt(args[0]) * 1000;
+        System.out.println("Running with timeout of " + timeout + "ms");
+        endTime = System.currentTimeMillis() + timeout;
         // First allocate the long lived objects and then run all phases.
         populateLongLived();
         runAllPhases();
--- old/test/hotspot/jtreg/gc/stress/systemgc/TestSystemGCWithCMS.java	2017-11-07 10:10:45.496361686 +0100
+++ new/test/hotspot/jtreg/gc/stress/systemgc/TestSystemGCWithCMS.java	2017-11-07 10:10:45.088349153 +0100
@@ -32,7 +32,7 @@
  * @run main/othervm/timeout=300 -Xlog:gc*=info -Xmx512m -XX:+UseConcMarkSweepGC TestSystemGCWithCMS 270
  */
 public class TestSystemGCWithCMS {
-    public static void main(String[] args) {
+    public static void main(String[] args) throws Exception {
         TestSystemGC.main(args);
     }
 }
--- old/test/hotspot/jtreg/gc/stress/systemgc/TestSystemGCWithG1.java	2017-11-07 10:10:46.914405245 +0100
+++ new/test/hotspot/jtreg/gc/stress/systemgc/TestSystemGCWithG1.java	2017-11-07 10:10:46.506392712 +0100
@@ -32,7 +32,7 @@
  * @run main/othervm/timeout=300 -Xlog:gc*=info -Xmx512m -XX:+UseG1GC TestSystemGCWithG1 270
  */
 public class TestSystemGCWithG1 {
-    public static void main(String[] args) {
+    public static void main(String[] args) throws Exception {
         TestSystemGC.main(args);
     }
 }
--- old/test/hotspot/jtreg/gc/stress/systemgc/TestSystemGCWithParallel.java	2017-11-07 10:10:48.347449264 +0100
+++ new/test/hotspot/jtreg/gc/stress/systemgc/TestSystemGCWithParallel.java	2017-11-07 10:10:47.932436516 +0100
@@ -32,7 +32,7 @@
  * @run main/othervm/timeout=300 -Xlog:gc=info -Xmx512m -XX:+UseParallelGC TestSystemGCWithParallel 270
  */
 public class TestSystemGCWithParallel {
-    public static void main(String[] args) {
+    public static void main(String[] args) throws Exception {
         TestSystemGC.main(args);
     }
 }
--- old/test/hotspot/jtreg/gc/stress/systemgc/TestSystemGCWithSerial.java	2017-11-07 10:10:49.784493406 +0100
+++ new/test/hotspot/jtreg/gc/stress/systemgc/TestSystemGCWithSerial.java	2017-11-07 10:10:49.371480719 +0100
@@ -32,7 +32,7 @@
  * @run main/othervm/timeout=300 -Xlog:gc*=info -Xmx512m -XX:+UseSerialGC TestSystemGCWithSerial 270
  */
 public class TestSystemGCWithSerial {
-    public static void main(String[] args) {
+    public static void main(String[] args) throws Exception {
         TestSystemGC.main(args);
     }
 }