7902936: Stray output in forked VM breaks external version parsing

Reviewed-by: shade

jmh-core-it/src/test/java/org/openjdk/jmh/it/jvmoption/JvmOptionTest.java

@@ -0,0 +1,67 @@
+/*
+ * Copyright (c) 2021, Oracle and/or its affiliates. All rights reserved.
+ * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
+ *
+ * This code is free software; you can redistribute it and/or modify it
+ * under the terms of the GNU General Public License version 2 only, as
+ * published by the Free Software Foundation.  Oracle designates this
+ * particular file as subject to the "Classpath" exception as provided
+ * by Oracle in the LICENSE file that accompanied this code.
+ *
+ * This code is distributed in the hope that it will be useful, but WITHOUT
+ * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
+ * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
+ * version 2 for more details (a copy is included in the LICENSE file that
+ * accompanied this code).
+ *
+ * You should have received a copy of the GNU General Public License version
+ * 2 along with this work; if not, write to the Free Software Foundation,
+ * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
+ *
+ * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
+ * or visit www.oracle.com if you need additional information or have any
+ * questions.
+ */
+package org.openjdk.jmh.it.jvmoption;
+
+import org.junit.Test;
+import org.openjdk.jmh.annotations.*;
+import org.openjdk.jmh.it.Fixtures;
+import org.openjdk.jmh.runner.Runner;
+import org.openjdk.jmh.runner.RunnerException;
+import org.openjdk.jmh.runner.options.Options;
+import org.openjdk.jmh.runner.options.OptionsBuilder;
+import org.openjdk.jmh.util.Utils;
+
+import java.nio.file.Path;
+import java.nio.file.Paths;
+import java.util.concurrent.TimeUnit;
+
+@Measurement(iterations = 1, time = 100, timeUnit = TimeUnit.MILLISECONDS)
+@Warmup(iterations = 1, time = 100, timeUnit = TimeUnit.MILLISECONDS)
+@Fork(1)
+@State(Scope.Thread)
+public class JvmOptionTest {
+
+    @Param("")
+    public String x;
+
+    @Benchmark
+    public void test() {
+        Fixtures.work();
+    }
+
+    @Test
+    public void test_api() throws RunnerException {
+        Path currentJvm = Paths.get(Utils.getCurrentJvm());
+        // Construct an alternative path to the JVM to exercise PrintPropertiesMain
+        Path alternativePathToJvm = currentJvm.getParent().resolve(".").resolve(currentJvm.getFileName());
+        Options opts = new OptionsBuilder()
+                .include(Fixtures.getTestMask(this.getClass()))
+                .shouldFailOnError(true)
+                .jvm(alternativePathToJvm.toString())
+                .build();
+
+        new Runner(opts).run();
+    }
+}

jmh-core/src/main/java/org/openjdk/jmh/runner/PrintPropertiesMain.java

@@ -26,6 +26,11 @@
 
 import org.openjdk.jmh.util.Utils;
 
+import java.io.BufferedOutputStream;
+import java.io.OutputStream;
+import java.nio.file.Files;
+import java.nio.file.Paths;
+
 /**
  * Main program entry point for exporting the system properties, used for detecting the VM version.
  */
@@ -35,10 +40,15 @@ class PrintPropertiesMain {
      * @param argv Command line arguments
      */
     public static void main(String[] argv) throws Exception {
-        Utils.getRecordedSystemProperties().storeToXML(
-                System.out,
-                "JMH properties export for target JVM",
-                "UTF-8");
+        if (argv.length != 1) {
+            throw new IllegalArgumentException("Usage: java " + PrintPropertiesMain.class.getName() + " <xml-output-file>");
+        }
+        try (OutputStream os = new BufferedOutputStream(Files.newOutputStream(Paths.get(argv[0])))) {
+            Utils.getRecordedSystemProperties().storeToXML(
+                    os,
+                    "JMH properties export for target JVM",
+                    "UTF-8");
+        }
     }
 
 }

jmh-core/src/main/java/org/openjdk/jmh/util/Utils.java

@@ -575,26 +575,20 @@ public static Properties getRecordedSystemProperties() {
     public static Properties readPropertiesFromCommand(List<String> cmd) {
         Properties out = new Properties();
         try {
-            Process p = new ProcessBuilder(cmd).start();
-
-            ByteArrayOutputStream baos = new ByteArrayOutputStream();
-
-            // drain streams, else we might lock up
-            InputStreamDrainer errDrainer = new InputStreamDrainer(p.getErrorStream(), System.err);
-            InputStreamDrainer outDrainer = new InputStreamDrainer(p.getInputStream(), baos);
-
-            errDrainer.start();
-            outDrainer.start();
+            File tempFile = FileUtils.tempFile("properties");
+            List<String> cmdWithFile = new ArrayList<>(cmd);
+            cmdWithFile.add(tempFile.getAbsolutePath());
+            Collection<String> errs = tryWith(cmdWithFile.toArray(new String[0]));
 
-            int err = p.waitFor();
-
-            errDrainer.join();
-            outDrainer.join();
-            out.loadFromXML(new ByteArrayInputStream(baos.toByteArray()));
+            if (!errs.isEmpty()) {
+                throw new RuntimeException("Unable to extract forked JVM properties using: '" + join(cmd, " ") + "'; " + errs);
+            }
+            try (InputStream in = new BufferedInputStream(new FileInputStream(tempFile))) {
+                // This will automatically pick UTF-8 based on the encoding in the XML declaration.
+                out.loadFromXML(in);
+            }
         } catch (IOException ex) {
             throw new RuntimeException(ex);
-        } catch (InterruptedException ex) {
-            throw new IllegalStateException(ex);
         }
         return out;
     }