ThreadUtils.sleepQuietly(Duration) now restores the current thread's

interrupt flag when catching InterruptedException.

Author: garydgregory

src/changes/changes.xml

@@ -113,6 +113,7 @@ The <action> type attribute can be add,update,fix,remove.
     <action issue="LANG-1816" type="fix" dev="ggregory" due-to="Ivan Ponomarev, Gary Gregory">ArrayUtils contains/indexOf/indexesOf with tolerance fail to match NaN values #1589.</action>
     <action                   type="fix" dev="ggregory" due-to="Ivan Ponomarev, Gary Gregory">Fix StringIndexOutOfBoundsException message in StrBuilder.append(char[], int, int).</action>
     <action issue="LANG-1818" type="fix" dev="ggregory" due-to="Ivan Ponomarev, Gary Gregory">Fix ClassUtils.getShortClassName(Class) to correctly handle $ in valid class names #1591.</action>
+    <action                   type="fix" dev="ggregory" due-to="Ivan Ponomarev, Gary Gregory">ThreadUtils.sleepQuietly(Duration) now restores the current thread's interrupt flag when catching InterruptedException.</action>
     <!-- ADD -->
     <action                   type="add" dev="ggregory" due-to="Gary Gregory">Add JavaVersion.JAVA_27.</action>
     <action                   type="add" dev="ggregory" due-to="Gary Gregory">Add SystemUtils.IS_JAVA_27.</action>

src/main/java/org/apache/commons/lang3/ThreadUtils.java

@@ -507,19 +507,21 @@ public static void sleep(final Duration duration) throws InterruptedException {
     }
 
     /**
-     * Sleeps for the given duration while ignoring {@link InterruptedException}.
+     * Sleeps for the given duration without throwing {@link InterruptedException}.
      * <p>
-     * The sleep duration may be shorter than duration if we catch a {@link InterruptedException}.
+     * The sleep duration may be shorter than the given duration if we catch a {@link InterruptedException}.
      * </p>
      *
      * @param duration the length of time to sleep.
+     * @see #sleep(Duration)
+     * @see Thread#interrupted()
      * @since 3.13.0
      */
     public static void sleepQuietly(final Duration duration) {
         try {
             sleep(duration);
         } catch (final InterruptedException ignore) {
-            // Ignore & be quiet.
+            Thread.currentThread().interrupt();
         }
     }
 

src/test/java/org/apache/commons/lang3/ThreadUtilsTest.java

@@ -36,6 +36,7 @@
 import java.util.List;
 import java.util.Objects;
 import java.util.concurrent.CountDownLatch;
+import java.util.concurrent.atomic.AtomicBoolean;
 import java.util.function.Predicate;
 
 import org.apache.commons.lang3.ThreadUtils.ThreadGroupPredicate;
@@ -245,6 +246,36 @@ void testSleepDuration() throws InterruptedException {
         ThreadUtils.sleep(Duration.ofMillis(1));
     }
 
+    @Test
+    void testSleepQuietlyInterruptDuringSleep() throws Exception {
+        final AtomicBoolean isInterrupted = new AtomicBoolean();
+        final Thread testThread = new Thread(() -> {
+            // This will be interrupted while sleeping
+            ThreadUtils.sleepQuietly(Duration.ofSeconds(10));
+            isInterrupted.set(Thread.currentThread().isInterrupted());
+        });
+        testThread.start();
+        Thread.sleep(100);
+        testThread.interrupt();
+        testThread.join(1000);
+        assertTrue(isInterrupted.get(), "Interrupted flag should be preserved after InterruptedException");
+    }
+
+    @Test
+    void testSleepQuietlyInterruptedFlagPreserved() {
+        Thread.currentThread().interrupt();
+        // Immediately throw InterruptedException and restores the interrupted status
+        ThreadUtils.sleepQuietly(Duration.ofMillis(1000));
+        assertTrue(Thread.interrupted(), "Interrupted flag should be preserved");
+    }
+
+    @Test
+    void testSleepQuietlyNormalNoInterrupt() {
+        Thread.interrupted();
+        ThreadUtils.sleepQuietly(Duration.ofMillis(10));
+        assertFalse(Thread.currentThread().isInterrupted(), "Interrupted flag should not be set for normal sleep");
+    }
+
     @Test
     void testSystemThreadGroupExists() {
         final ThreadGroup systemThreadGroup = ThreadUtils.getSystemThreadGroup();