Fix shutdownDisable not taking effect(#2614)

Author: Pluto-syd

log4j-core-test/src/test/java/org/apache/logging/log4j/core/ShutdownDisabledTest.java

@@ -17,16 +17,24 @@
 package org.apache.logging.log4j.core;
 
 import static org.junit.jupiter.api.Assertions.assertFalse;
+import static org.junit.jupiter.api.Assertions.assertNull;
 
+import java.lang.reflect.Field;
 import org.apache.logging.log4j.core.config.Configuration;
 import org.apache.logging.log4j.core.test.junit.LoggerContextSource;
+import org.apache.logging.log4j.core.util.ReflectionUtil;
+import org.apache.logging.log4j.test.junit.SetTestProperty;
 import org.junit.jupiter.api.Test;
 
+@SetTestProperty(key = "log4j2.is.webapp", value = "false")
 @LoggerContextSource("log4j-test3.xml")
 class ShutdownDisabledTest {
 
     @Test
-    void testShutdownFlag(final Configuration config) {
+    void testShutdownFlag(final Configuration config, final LoggerContext ctx) throws NoSuchFieldException {
+        Field shutdownCallback = LoggerContext.class.getDeclaredField("shutdownCallback");
+        Object fieldValue = ReflectionUtil.getFieldValue(shutdownCallback, ctx);
         assertFalse(config.isShutdownHookEnabled(), "Shutdown hook is enabled");
+        assertNull(fieldValue, "Shutdown callback is null");
     }
 }

log4j-core-test/src/test/resources/log4j-test3.xml

@@ -15,7 +15,7 @@
   ~ See the License for the specific language governing permissions and
   ~ limitations under the License.
   -->
-<Configuration status="OFF" name="XMLConfigTest" monitorInterval="5" shutdownHook="disable">
+<Configuration status="DEBUG" name="XMLConfigTest" monitorInterval="5" shutdownHook="disable">
   <Appenders>
     <Console name="STDOUT">
       <PatternLayout pattern="%m MDC%X%n"/>

log4j-core/src/main/java/org/apache/logging/log4j/core/LoggerContext.java

@@ -321,6 +321,8 @@ public void start(final Configuration config) {
         if (configLock.tryLock()) {
             try {
                 if (this.isInitialized() || this.isStopped()) {
+                    this.setStarting();
+                    setConfiguration(config);
                     if (this.configuration.isShutdownHookEnabled()) {
                         setUpShutdownHook();
                     }
@@ -330,7 +332,6 @@ public void start(final Configuration config) {
                 configLock.unlock();
             }
         }
-        setConfiguration(config);
         LOGGER.info("{}[name={}] started with configuration {}.", getClass().getSimpleName(), getName(), config);
     }