--- a/test/lib/jdk/test/lib/cds/CDSTestUtils.java	Thu Aug 23 11:33:51 2018 -0400
+++ b/test/lib/jdk/test/lib/cds/CDSTestUtils.java	Thu Aug 23 09:35:09 2018 -0700
@@ -200,11 +200,19 @@
         }
     }
 
-    // Specify this property to copy sdandard output of the child test process to
-    // the parent/main stdout of the test.
-    // By default such output is logged into a file, and is copied into the main stdout.
-    public static final boolean CopyChildStdoutToMainStdout =
-        Boolean.valueOf(System.getProperty("test.cds.copy.child.stdout", "true"));
+    // A number to be included in the filename of the stdout and the stderr output file.
+    static int logCounter = 0;
+
+    private static int getNextLogCounter() {
+        return logCounter++;
+    }
+
+    // By default, stdout of child processes are logged in files such as
+    // <testname>-0000-exec.stdout. If you want to also include the stdout
+    // inside jtr files, you can override this in the jtreg command line like
+    // "jtreg -Dtest.cds.copy.child.stdout=true ...."
+    public static final boolean copyChildStdoutToMainStdout =
+        Boolean.getBoolean("test.cds.copy.child.stdout");
 
     // This property is passed to child test processes
     public static final String TestTimeoutFactor = System.getProperty("test.timeout.factor", "1.0");
@@ -549,13 +557,17 @@
     public static OutputAnalyzer executeAndLog(ProcessBuilder pb, String logName) throws Exception {
         long started = System.currentTimeMillis();
         OutputAnalyzer output = new OutputAnalyzer(pb.start());
+        String outputFileNamePrefix =
+            getTestName() + "-" + String.format("%04d", getNextLogCounter()) + "-" + logName;
 
-        writeFile(getOutputFile(logName + ".stdout"), output.getStdout());
-        writeFile(getOutputFile(logName + ".stderr"), output.getStderr());
+        writeFile(getOutputFile(outputFileNamePrefix + ".stdout"), output.getStdout());
+        writeFile(getOutputFile(outputFileNamePrefix + ".stderr"), output.getStderr());
         System.out.println("[ELAPSED: " + (System.currentTimeMillis() - started) + " ms]");
+        System.out.println("[logging stdout to " + outputFileNamePrefix + ".stdout]");
+        System.out.println("[logging stderr to " + outputFileNamePrefix + ".stderr]");
         System.out.println("[STDERR]\n" + output.getStderr());
 
-        if (CopyChildStdoutToMainStdout)
+        if (copyChildStdoutToMainStdout)
             System.out.println("[STDOUT]\n" + output.getStdout());
 
         return output;