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

…ue) (elastic#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.

On 7.4, we also warn for io.netty.allocator.type.

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 Map<String, String> systemProperties = extractSystemProperties(userDefinedJvmOptions);
         if (systemProperties.containsKey("io.netty.allocator.type") == false) {
+            if (System.getProperty("os.name").startsWith("Windows") && JavaVersion.majorVersion(JavaVersion.CURRENT) == 8) {
+                Launchers.errPrintln("Warning: with JDK 8 on Windows, Elasticsearch may miscalculate io.netty.allocator.type");
+                Launchers.errPrintln("  due to a JDK issue (JDK-8074459).");
+                Launchers.errPrintln("  Please use a newer version of Java or set io.netty.allocator.type explicitly");
+            }
             if (heapSize <= 1 << 30) {
                 ergonomicChoices.add("-Dio.netty.allocator.type=unpooled");
             } else {
@@ -66,6 +73,11 @@ static List<String> choose(final List<String> userDefinedJvmOptions) throws Inte
         }
         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));
@@ -132,6 +132,7 @@ public void testPooledMemoryChoiceOnSmallHeap() throws InterruptedException, IOE
     }
 
     public void testPooledMemoryChoiceOnNotSmallHeap() 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 String largeHeap = randomFrom(Arrays.asList("1025M", "2048M", "2G", "8G"));
         assertThat(
@@ -140,6 +141,7 @@ public void testPooledMemoryChoiceOnNotSmallHeap() throws InterruptedException,
     }
 
     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));