Warn when MaxDirectMemorySize may be incorrect (Windows/JDK8 only iss…

…ue) (#48365)

Our JVM ergonomics extract max heap size from JDK PrintFlagsFinal output. 
On JDK 8, there is a system-dependent bug where memory sizes are cast to 
32-bit integers. On affected systems (namely, Windows), when 1/4 of physical
memory is more than the maximum integer value, the output of PrintFlagsFinal
will be inaccurate. In the pathological case, where the max heap size would
be a multiple of 4g, the test will fail.

The practical effect of this bug, beyond test failures, is that we may set
MaxDirectMemorySize to an incorrect value on Windows. This commit adds a
warning about this situation during startup.

distribution/tools/launchers/src/main/java/org/elasticsearch/tools/launchers/JvmErgonomics.java

@@ -19,6 +19,8 @@
 
 package org.elasticsearch.tools.launchers;
 
+import org.elasticsearch.tools.java_version_checker.JavaVersion;
+
 import java.io.BufferedReader;
 import java.io.IOException;
 import java.io.InputStream;
@@ -58,6 +60,11 @@ static List<String> choose(final List<String> userDefinedJvmOptions) throws Inte
         final long heapSize = extractHeapSize(finalJvmOptions);
         final long maxDirectMemorySize = extractMaxDirectMemorySize(finalJvmOptions);
         if (maxDirectMemorySize == 0) {
+            if (System.getProperty("os.name").startsWith("Windows") && JavaVersion.majorVersion(JavaVersion.CURRENT) == 8) {
+                Launchers.errPrintln("Warning: with JDK 8 on Windows, Elasticsearch may miscalculate MaxDirectMemorySize");
+                Launchers.errPrintln("  due to a JDK issue (JDK-8074459).");
+                Launchers.errPrintln("  Please use a newer version of Java or set MaxDirectMemorySize explicitly");
+            }
             ergonomicChoices.add("-XX:MaxDirectMemorySize=" + heapSize / 2);
         }
         return ergonomicChoices;

distribution/tools/launchers/src/test/java/org/elasticsearch/tools/launchers/JvmErgonomicsTests.java

@@ -56,8 +56,8 @@ public void testExtractValidHeapSizeUsingMaxHeapSize() throws InterruptedExcepti
     }
 
     public void testExtractValidHeapSizeNoOptionPresent() throws InterruptedException, IOException {
-        // Muting on Windows, awaitsfix: https://github.com/elastic/elasticsearch/issues/47384
-        assumeFalse(System.getProperty("os.name").startsWith("Windows"));
+        // Muted for jdk8/Windows, see: https://github.com/elastic/elasticsearch/issues/47384
+        assumeFalse(System.getProperty("os.name").startsWith("Windows") && JavaVersion.majorVersion(JavaVersion.CURRENT) == 8);
         assertThat(
                 JvmErgonomics.extractHeapSize(JvmErgonomics.finalJvmOptions(Collections.emptyList())),
                 greaterThan(0L));
@@ -123,8 +123,9 @@ public void testExtractNoSystemProperties() {
         Map<String, String> parsedSystemProperties = JvmErgonomics.extractSystemProperties(Arrays.asList("-Xms1024M", "-Xmx1024M"));
         assertTrue(parsedSystemProperties.isEmpty());
     }
-    
+
     public void testMaxDirectMemorySizeChoice() throws InterruptedException, IOException {
+        // Muted for jdk8/Windows, see: https://github.com/elastic/elasticsearch/issues/47384
         assumeFalse(System.getProperty("os.name").startsWith("Windows") && JavaVersion.majorVersion(JavaVersion.CURRENT) == 8);
         final Map<String, String> heapMaxDirectMemorySize = new HashMap<>();
         heapMaxDirectMemorySize.put("64M", Long.toString((64L << 20) / 2));