Try to convince the JVM not to lose stacktraces

buildSrc/src/main/groovy/org/elasticsearch/gradle/BuildPlugin.groovy

@@ -469,6 +469,7 @@ class BuildPlugin implements Plugin<Project> {
             heapdumpDir.mkdirs()
             jvmArg '-XX:HeapDumpPath=' + heapdumpDir
             argLine System.getProperty('tests.jvm.argline')
+            argLine '-XX:-OmitStackTraceInFastThrow'
 
             // we use './temp' since this is per JVM and tests are forbidden from writing to CWD
             systemProperty 'java.io.tmpdir', './temp'

distribution/src/main/resources/config/jvm.options

@@ -62,6 +62,10 @@
 # use our provided JNA always versus the system one
 -Djna.nosys=true
 
+# turn off a JDK optimization that throws away stack traces for common
+# exceptions because stack traces are important for debugging
+-XX:-OmitStackTraceInFastThrow
+
 # use old-style file permissions on JDK9
 -Djdk.io.permissionsUseCanonicalPath=true
 

modules/lang-painless/src/test/java/org/elasticsearch/painless/ArrayLikeObjectTestCase.java

@@ -80,9 +80,14 @@ private void expectOutOfBounds(int index, String script, Object val) {
         IndexOutOfBoundsException e = expectScriptThrows(IndexOutOfBoundsException.class, () ->
             exec(script, singletonMap("val", val), true));
         try {
+            /* If this fails you *might* be missing -XX:-OmitStackTraceInFastThrow in the test jvm
+             * In Eclipse you can add this by default by going to Preference->Java->Installed JREs,
+             * clicking on the default JRE, clicking edit, and adding the flag to the
+             * "Default VM Arguments".
+             */
             assertThat(e.getMessage(), outOfBoundsExceptionMessageMatcher(index, 5));
         } catch (AssertionError ae) {
-            ae.addSuppressed(e);   // Mark the exception we are testing as suppressed so we get its stack trace. If it has one :(
+            ae.addSuppressed(e);   // Mark the exception we are testing as suppressed so we get its stack trace.
             throw ae;
         }
     }

modules/lang-painless/src/test/java/org/elasticsearch/painless/ListTests.java

@@ -25,9 +25,7 @@
 import java.util.Arrays;
 import java.util.List;
 
-import static org.hamcrest.Matchers.anyOf;
 import static org.hamcrest.Matchers.equalTo;
-import static org.hamcrest.Matchers.nullValue;
 
 /** Tests for working with lists. */
 public class ListTests extends ArrayLikeObjectTestCase {
@@ -61,10 +59,7 @@ protected Matcher<String> outOfBoundsExceptionMessageMatcher(int index, int size
             if (index > size) {
                 return equalTo("Index: " + index + ", Size: " + size);
             }
-            Matcher<String> matcher = equalTo(Integer.toString(index));
-            // If we set -XX:-OmitStackTraceInFastThrow we wouldn't need this
-            matcher = anyOf(matcher, nullValue());
-            return matcher;
+            return equalTo(Integer.toString(index));
         } else {
             // This exception is locale dependent so we attempt to reproduce it
             List<Object> list = new ArrayList<>();

modules/lang-painless/src/test/java/org/elasticsearch/painless/ScriptTestCase.java

@@ -128,12 +128,13 @@ public static <T extends Throwable> T expectScriptThrows(Class<T> expectedType,
             if (e instanceof ScriptException) {
                 boolean hasEmptyScriptStack = ((ScriptException) e).getScriptStack().isEmpty();
                 if (shouldHaveScriptStack && hasEmptyScriptStack) {
-                    if (0 != e.getCause().getStackTrace().length) {
-                        // Without -XX:-OmitStackTraceInFastThrow the jvm can eat the stack trace which causes us to ignore script_stack
-                        AssertionFailedError assertion = new AssertionFailedError("ScriptException should have a scriptStack");
-                        assertion.initCause(e);
-                        throw assertion;
-                    }
+                    /* If this fails you *might* be missing -XX:-OmitStackTraceInFastThrow in the test jvm
+                     * In Eclipse you can add this by default by going to Preference->Java->Installed JREs,
+                     * clicking on the default JRE, clicking edit, and adding the flag to the
+                     * "Default VM Arguments". */
+                    AssertionFailedError assertion = new AssertionFailedError("ScriptException should have a scriptStack");
+                    assertion.initCause(e);
+                    throw assertion;
                 } else if (false == shouldHaveScriptStack && false == hasEmptyScriptStack) {
                     AssertionFailedError assertion = new AssertionFailedError("ScriptException shouldn't have a scriptStack");
                     assertion.initCause(e);