From 7af0923b01e48b44f7f49aeacbc5a28d82c8975f Mon Sep 17 00:00:00 2001
From: Albert Yang <albert.m.yang@oracle.com>
Date: Thu, 21 Aug 2025 11:48:06 +0200
Subject: [PATCH 1/2] test-nano-time

---
 .../vmTestbase/nsk/share/test/Stresser.java   | 35 +++++++++----------
 1 file changed, 17 insertions(+), 18 deletions(-)

diff --git a/test/hotspot/jtreg/vmTestbase/nsk/share/test/Stresser.java b/test/hotspot/jtreg/vmTestbase/nsk/share/test/Stresser.java
index 83e8baa283699..98f18bc2f1519 100644
--- a/test/hotspot/jtreg/vmTestbase/nsk/share/test/Stresser.java
+++ b/test/hotspot/jtreg/vmTestbase/nsk/share/test/Stresser.java
@@ -58,9 +58,11 @@ public class Stresser implements ExecutionController {
     private String name;
     private long maxIterations;
     private long iterations;
+
+    // In milliseconds
     private long startTime;
-    private long finishTime;
     private long currentTime;
+
     private PrintStream defaultOutput = System.out;
 
     /*
@@ -179,15 +181,15 @@ public void printStressInfo(PrintStream out) {
      */
     public void printExecutionInfo(PrintStream out) {
         println(out, "Completed iterations: " + iterations);
-        println(out, "Execution time: " + (currentTime - startTime) + " seconds");
+        println(out, "Execution time: " + (currentTime - startTime)/1000.0 + " seconds");
         if (!finished) {
             println(out, "Execution is not finished yet");
         } else if (forceFinish) {
             println(out, "Execution was forced to finish");
         } else if (maxIterations != 0 && iterations >= maxIterations) {
             println(out, "Execution finished because number of iterations was exceeded: " + iterations + " >= " + maxIterations);
-        } else if (finishTime != 0 && currentTime >= finishTime) {
-            println(out, "Execution finished because time was exceeded: " + (currentTime - startTime) + " >= " + (finishTime - startTime));
+        } else if (options.getTime() != 0 && (currentTime - startTime) >= options.getTime() * 1000) {
+            println(out, "Execution finished because time was exceeded: " + (currentTime - startTime) + " >= " + options.getTime() * 1000);
         }
     }
 
@@ -209,12 +211,7 @@ public void start(long stdIterations) {
         maxIterations = stdIterations * options.getIterationsFactor();
         iterations = 0;
         long stressTime = options.getTime();
-        startTime = System.currentTimeMillis();
-        if (stressTime == 0) {
-            finishTime = 0;
-        } else {
-            finishTime = startTime + stressTime * 1000;
-        }
+        startTime = System.nanoTime()/1000000;
         finished = false;
         forceFinish = false;
         if (options.isDebugEnabled()) {
@@ -232,7 +229,7 @@ public void start(long stdIterations) {
      * finally {} block.
      */
     public void finish() {
-        currentTime = System.currentTimeMillis();
+        currentTime = System.nanoTime()/1000000;
         finished = true;
         if (options.isDebugEnabled()) {
             printExecutionInfo(defaultOutput);
@@ -255,10 +252,12 @@ public void forceFinish() {
      */
     public boolean iteration() {
         ++iterations;
+        boolean result = continueExecution();
+        // Call print at the end to show the most up-to-date info.
         if (options.isDebugDetailed()) {
             printExecutionInfo(defaultOutput);
         }
-        return continueExecution();
+        return result;
     }
 
     /**
@@ -267,14 +266,14 @@ public boolean iteration() {
      * @return true if execution needs to continue
      */
     public boolean continueExecution() {
-        currentTime = System.currentTimeMillis();
+        currentTime = System.nanoTime()/1000000;
         if (startTime == 0) {
             throw new TestBug("Stresser is not started.");
         }
         return !forceFinish
                 && !finished
                 && (maxIterations == 0 || iterations < maxIterations)
-                && (finishTime == 0 || currentTime < finishTime);
+                && (options.getTime() == 0 || (currentTime - startTime) < options.getTime() * 1000);
     }
 
     /**
@@ -309,7 +308,7 @@ public long getIterationsLeft() {
      * @return time
      */
     public long getExecutionTime() {
-        return System.currentTimeMillis() - startTime;
+        return System.nanoTime()/1000000 - startTime;
     }
 
     /**
@@ -318,11 +317,11 @@ public long getExecutionTime() {
      * @return time
      */
     public long getTimeLeft() {
-        long current = System.currentTimeMillis();
-        if (current >= finishTime) {
+        long elapsedTime = System.nanoTime()/1000000 - startTime;
+        if (elapsedTime >= options.getTime() * 1000) {
             return 0;
         } else {
-            return finishTime - current;
+            return options.getTime() * 1000 - elapsedTime;
         }
     }
 

From cefb9948e6770fd4cf81de001f072c3e0a4f0f5f Mon Sep 17 00:00:00 2001
From: Albert Yang <albert.m.yang@oracle.com>
Date: Fri, 22 Aug 2025 20:33:49 +0200
Subject: [PATCH 2/2] review

---
 test/hotspot/jtreg/vmTestbase/nsk/share/test/Stresser.java | 5 +++--
 1 file changed, 3 insertions(+), 2 deletions(-)

diff --git a/test/hotspot/jtreg/vmTestbase/nsk/share/test/Stresser.java b/test/hotspot/jtreg/vmTestbase/nsk/share/test/Stresser.java
index 98f18bc2f1519..4ce233a697a67 100644
--- a/test/hotspot/jtreg/vmTestbase/nsk/share/test/Stresser.java
+++ b/test/hotspot/jtreg/vmTestbase/nsk/share/test/Stresser.java
@@ -318,10 +318,11 @@ public long getExecutionTime() {
      */
     public long getTimeLeft() {
         long elapsedTime = System.nanoTime()/1000000 - startTime;
-        if (elapsedTime >= options.getTime() * 1000) {
+        long stressTime = options.getTime() * 1000;
+        if (elapsedTime >= stressTime) {
             return 0;
         } else {
-            return options.getTime() * 1000 - elapsedTime;
+            return stressTime - elapsedTime;
         }
     }