Handle missing stack traces in ExtendedThreadInformation

log4j-core-test/src/test/java/org/apache/logging/log4j/core/message/ExtendedThreadInformationTest.java

@@ -16,10 +16,17 @@
  */
 package org.apache.logging.log4j.core.message;
 
+import static org.hamcrest.CoreMatchers.containsString;
+import static org.hamcrest.MatcherAssert.assertThat;
 import static org.junit.jupiter.api.Assertions.assertTrue;
+import static org.mockito.Mockito.mock;
+import static org.mockito.Mockito.when;
 
+import java.lang.management.ThreadInfo;
 import org.apache.logging.log4j.message.ThreadDumpMessage;
 import org.junit.jupiter.api.Test;
+import org.junit.jupiter.params.ParameterizedTest;
+import org.junit.jupiter.params.provider.EnumSource;
 
 /**
  * Tests that ThreadDumpMessage uses ExtendedThreadInformation when available.
@@ -33,4 +40,42 @@ void testMessage() {
         // System.out.print(message);
         assertTrue(message.contains(" Id="), "No header");
     }
+
+    @ParameterizedTest
+    @EnumSource(Thread.State.class)
+    void testMessageWithNullStackTrace(final Thread.State state) {
+        obtainMessageWithMissingStackTrace(state, null);
+    }
+
+    @ParameterizedTest
+    @EnumSource(Thread.State.class)
+    void testMessageWithEmptyStackTrace(final Thread.State state) {
+        obtainMessageWithMissingStackTrace(state, new StackTraceElement[0]);
+    }
+
+    private void obtainMessageWithMissingStackTrace(final Thread.State state, final StackTraceElement[] stackTrace) {
+        // setup
+        final String threadName = "the thread name";
+        final long threadId = 23523L;
+
+        final ThreadInfo threadInfo = mock(ThreadInfo.class);
+        when(threadInfo.getStackTrace()).thenReturn(stackTrace);
+        when(threadInfo.getThreadName()).thenReturn(threadName);
+        when(threadInfo.getThreadId()).thenReturn(threadId);
+        when(threadInfo.isSuspended()).thenReturn(true);
+        when(threadInfo.isInNative()).thenReturn(true);
+        when(threadInfo.getThreadState()).thenReturn(state);
+
+        // given
+        final ExtendedThreadInformation sut = new ExtendedThreadInformation(threadInfo);
+
+        // when
+        final StringBuilder result = new StringBuilder();
+        sut.printThreadInfo(result);
+
+        // then
+        assertThat(result.toString(), containsString(threadName));
+        assertThat(result.toString(), containsString(state.name()));
+        assertThat(result.toString(), containsString(String.valueOf(threadId)));
+    }
 }

log4j-core/src/main/java/org/apache/logging/log4j/core/message/ExtendedThreadInformation.java

@@ -23,6 +23,7 @@
 import java.lang.management.ThreadInfo;
 import org.apache.logging.log4j.message.ThreadInformation;
 import org.apache.logging.log4j.util.StringBuilders;
+import org.jspecify.annotations.Nullable;
 
 /**
  * Provides information on locks and monitors in the thread dump. This class requires Java 1.6 to compile and
@@ -119,17 +120,17 @@ private void formatState(final StringBuilder sb, final ThreadInfo info) {
                 break;
             }
             case WAITING: {
-                final StackTraceElement element = info.getStackTrace()[0];
-                final String className = element.getClassName();
-                final String method = element.getMethodName();
-                if (className.equals("java.lang.Object") && method.equals("wait")) {
+                final StackTraceElement element = getFirstStackTraceElement(info);
+                final String className = element != null ? element.getClassName() : null;
+                final String method = element != null ? element.getMethodName() : null;
+                if ("java.lang.Object".equals(className) && "wait".equals(method)) {
                     sb.append(" (on object monitor");
                     if (info.getLockOwnerName() != null) {
                         sb.append(" owned by \"");
                         sb.append(info.getLockOwnerName()).append("\" Id=").append(info.getLockOwnerId());
                     }
                     sb.append(')');
-                } else if (className.equals("java.lang.Thread") && method.equals("join")) {
+                } else if ("java.lang.Thread".equals(className) && "join".equals(method)) {
                     sb.append(" (on completion of thread ")
                             .append(info.getLockOwnerId())
                             .append(')');
@@ -144,19 +145,19 @@ private void formatState(final StringBuilder sb, final ThreadInfo info) {
                 break;
             }
             case TIMED_WAITING: {
-                final StackTraceElement element = info.getStackTrace()[0];
-                final String className = element.getClassName();
-                final String method = element.getMethodName();
-                if (className.equals("java.lang.Object") && method.equals("wait")) {
+                final StackTraceElement element = getFirstStackTraceElement(info);
+                final String className = element != null ? element.getClassName() : null;
+                final String method = element != null ? element.getMethodName() : null;
+                if ("java.lang.Object".equals(className) && "wait".equals(method)) {
                     sb.append(" (on object monitor");
                     if (info.getLockOwnerName() != null) {
                         sb.append(" owned by \"");
                         sb.append(info.getLockOwnerName()).append("\" Id=").append(info.getLockOwnerId());
                     }
                     sb.append(')');
-                } else if (className.equals("java.lang.Thread") && method.equals("sleep")) {
+                } else if ("java.lang.Thread".equals(className) && "sleep".equals(method)) {
                     sb.append(" (sleeping)");
-                } else if (className.equals("java.lang.Thread") && method.equals("join")) {
+                } else if ("java.lang.Thread".equals(className) && "join".equals(method)) {
                     sb.append(" (on completion of thread ")
                             .append(info.getLockOwnerId())
                             .append(')');
@@ -174,4 +175,10 @@ private void formatState(final StringBuilder sb, final ThreadInfo info) {
                 break;
         }
     }
+
+    @Nullable
+    private static StackTraceElement getFirstStackTraceElement(final ThreadInfo info) {
+        final StackTraceElement[] stackTrace = info.getStackTrace();
+        return stackTrace != null && stackTrace.length > 0 ? stackTrace[0] : null;
+    }
 }

src/changelog/.2.x.x/3655_handle_missing_stack_traces_in_ExtendedThreadInformation.xml

@@ -0,0 +1,10 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<entry xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
+       xmlns="https://logging.apache.org/xml/ns"
+       xsi:schemaLocation="https://logging.apache.org/xml/ns https://logging.apache.org/xml/ns/log4j-changelog-0.xsd"
+       type="fixed">
+  <issue id="3655" link="https://github.com/apache/logging-log4j2/pull/3655"/>
+  <description format="asciidoc">
+    Fix `ArrayIndexOutOfBoundsException` on invocation of `Message.getFormattedMessage()` when any thread has no stack trace, which occurs on some JVM implementations.
+  </description>
+</entry>