diff --git a/core-java/src/main/java/com/baeldung/concurrent/skiplist/Event.java b/core-java/src/main/java/com/baeldung/concurrent/skiplist/Event.java
new file mode 100644
index 0000000000..ce1f57bb93
--- /dev/null
+++ b/core-java/src/main/java/com/baeldung/concurrent/skiplist/Event.java
@@ -0,0 +1,21 @@
+package com.baeldung.concurrent.skiplist;
+
+import java.time.ZonedDateTime;
+
+public class Event {
+    private final ZonedDateTime eventTime;
+    private final String content;
+
+    public Event(ZonedDateTime eventTime, String content) {
+        this.eventTime = eventTime;
+        this.content = content;
+    }
+
+    public ZonedDateTime getEventTime() {
+        return eventTime;
+    }
+
+    public String getContent() {
+        return content;
+    }
+}
diff --git a/core-java/src/main/java/com/baeldung/concurrent/skiplist/EventWindowSort.java b/core-java/src/main/java/com/baeldung/concurrent/skiplist/EventWindowSort.java
new file mode 100644
index 0000000000..9eef00bd3f
--- /dev/null
+++ b/core-java/src/main/java/com/baeldung/concurrent/skiplist/EventWindowSort.java
@@ -0,0 +1,36 @@
+package com.baeldung.concurrent.skiplist;
+
+import java.time.ZonedDateTime;
+import java.util.Comparator;
+import java.util.concurrent.ConcurrentNavigableMap;
+import java.util.concurrent.ConcurrentSkipListMap;
+import java.util.function.ToLongFunction;
+
+public class EventWindowSort {
+    private final ConcurrentSkipListMap<ZonedDateTime, String> events = new ConcurrentSkipListMap<>(Comparator.comparingLong(new ToLongFunction<ZonedDateTime>() {
+        @Override
+        public long applyAsLong(ZonedDateTime value) {
+            return value
+              .toInstant()
+              .toEpochMilli();
+        }
+    }));
+
+    public void acceptEvent(Event event) {
+        events.put(event.getEventTime(), event.getContent());
+    }
+
+    public ConcurrentNavigableMap<ZonedDateTime, String> getEventsFromLastMinute() {
+        return events.tailMap(ZonedDateTime
+          .now()
+          .minusMinutes(1));
+    }
+
+    public ConcurrentNavigableMap<ZonedDateTime, String> getEventsOlderThatOneMinute() {
+        return events.headMap(ZonedDateTime
+          .now()
+          .minusMinutes(1));
+    }
+
+}
+
diff --git a/core-java/src/test/java/com/baeldung/concurrent/skiplist/ConcurrentSkipListSetTest.java b/core-java/src/test/java/com/baeldung/concurrent/skiplist/ConcurrentSkipListSetTest.java
new file mode 100644
index 0000000000..a2dbbae520
--- /dev/null
+++ b/core-java/src/test/java/com/baeldung/concurrent/skiplist/ConcurrentSkipListSetTest.java
@@ -0,0 +1,120 @@
+package com.baeldung.concurrent.skiplist;
+
+import org.junit.Test;
+
+import java.time.ZonedDateTime;
+import java.util.UUID;
+import java.util.concurrent.ConcurrentNavigableMap;
+import java.util.concurrent.ExecutorService;
+import java.util.concurrent.Executors;
+import java.util.concurrent.TimeUnit;
+import java.util.stream.IntStream;
+
+import static org.junit.Assert.assertEquals;
+import static org.junit.Assert.assertTrue;
+
+public class ConcurrentSkipListSetTest {
+
+    @Test
+    public void givenThreadsProducingEvents_whenGetForEventsFromLastMinute_thenReturnThoseEventsInTheLockFreeWay() throws InterruptedException {
+        //given
+        ExecutorService executorService = Executors.newFixedThreadPool(3);
+        EventWindowSort eventWindowSort = new EventWindowSort();
+        int numberOfThreads = 2;
+        //when
+        Runnable producer = () -> IntStream
+          .rangeClosed(0, 100)
+          .forEach(index -> eventWindowSort.acceptEvent(new Event(ZonedDateTime
+            .now()
+            .minusSeconds(index), UUID
+            .randomUUID()
+            .toString())));
+
+        for (int i = 0; i < numberOfThreads; i++) {
+            executorService.execute(producer);
+        }
+
+        Thread.sleep(500);
+
+        ConcurrentNavigableMap<ZonedDateTime, String> eventsFromLastMinute = eventWindowSort.getEventsFromLastMinute();
+
+        long eventsOlderThanOneMinute = eventsFromLastMinute
+          .entrySet()
+          .stream()
+          .filter(e -> e
+            .getKey()
+            .isBefore(ZonedDateTime
+              .now()
+              .minusMinutes(1)))
+          .count();
+        assertEquals(eventsOlderThanOneMinute, 0);
+
+        long eventYoungerThanOneMinute = eventsFromLastMinute
+          .entrySet()
+          .stream()
+          .filter(e -> e
+            .getKey()
+            .isAfter(ZonedDateTime
+              .now()
+              .minusMinutes(1)))
+          .count();
+
+        //then
+        assertTrue(eventYoungerThanOneMinute > 0);
+
+        executorService.awaitTermination(1, TimeUnit.SECONDS);
+        executorService.shutdown();
+    }
+
+    @Test
+    public void givenThreadsProducingEvents_whenGetForEventsOlderThanOneMinute_thenReturnThoseEventsInTheLockFreeWay() throws InterruptedException {
+        //given
+        ExecutorService executorService = Executors.newFixedThreadPool(3);
+        EventWindowSort eventWindowSort = new EventWindowSort();
+        int numberOfThreads = 2;
+        //when
+        Runnable producer = () -> IntStream
+          .rangeClosed(0, 100)
+          .forEach(index -> eventWindowSort.acceptEvent(new Event(ZonedDateTime
+            .now()
+            .minusSeconds(index), UUID
+            .randomUUID()
+            .toString())));
+
+        for (int i = 0; i < numberOfThreads; i++) {
+            executorService.execute(producer);
+        }
+
+        Thread.sleep(500);
+
+        ConcurrentNavigableMap<ZonedDateTime, String> eventsFromLastMinute = eventWindowSort.getEventsOlderThatOneMinute();
+
+        long eventsOlderThanOneMinute = eventsFromLastMinute
+          .entrySet()
+          .stream()
+          .filter(e -> e
+            .getKey()
+            .isBefore(ZonedDateTime
+              .now()
+              .minusMinutes(1)))
+          .count();
+        assertTrue(eventsOlderThanOneMinute > 0);
+
+        long eventYoungerThanOneMinute = eventsFromLastMinute
+          .entrySet()
+          .stream()
+          .filter(e -> e
+            .getKey()
+            .isAfter(ZonedDateTime
+              .now()
+              .minusMinutes(1)))
+          .count();
+
+        //then
+        assertEquals(eventYoungerThanOneMinute, 0);
+
+        executorService.awaitTermination(1, TimeUnit.SECONDS);
+        executorService.shutdown();
+    }
+
+}
\ No newline at end of file