diff --git a/rsocket-core/src/main/java/io/rsocket/internal/UnboundedProcessor.java b/rsocket-core/src/main/java/io/rsocket/internal/UnboundedProcessor.java
index cb8b5d63d..d2a438dfd 100644
--- a/rsocket-core/src/main/java/io/rsocket/internal/UnboundedProcessor.java
+++ b/rsocket-core/src/main/java/io/rsocket/internal/UnboundedProcessor.java
@@ -20,6 +20,7 @@
 import io.rsocket.internal.jctools.queues.MpscUnboundedArrayQueue;
 import java.util.Objects;
 import java.util.Queue;
+import java.util.concurrent.CancellationException;
 import java.util.concurrent.atomic.AtomicIntegerFieldUpdater;
 import java.util.concurrent.atomic.AtomicLongFieldUpdater;
 import org.reactivestreams.Subscriber;
@@ -55,6 +56,8 @@ public final class UnboundedProcessor<T> extends FluxProcessor<T, T>
 
   volatile boolean cancelled;
 
+  volatile boolean terminated;
+
   volatile int once;
 
   @SuppressWarnings("rawtypes")
@@ -124,6 +127,9 @@ void drainRegular(Subscriber<? super T> a) {
         }
 
         if (checkTerminated(d, empty, a)) {
+          if (!empty) {
+            release(t);
+          }
           return;
         }
 
@@ -159,7 +165,9 @@ void drainFused(Subscriber<? super T> a) {
     for (; ; ) {
 
       if (cancelled) {
-        this.clear();
+        if (terminated) {
+          this.clear();
+        }
         hasDownstream = false;
         return;
       }
@@ -189,7 +197,7 @@ void drainFused(Subscriber<? super T> a) {
 
   public void drain() {
     if (WIP.getAndIncrement(this) != 0) {
-      if (cancelled) {
+      if ((!outputFused && cancelled) || terminated) {
         this.clear();
       }
       return;
@@ -350,7 +358,9 @@ public void cancel() {
     cancelled = true;
 
     if (WIP.getAndIncrement(this) == 0) {
-      this.clear();
+      if (!outputFused || terminated) {
+        this.clear();
+      }
       hasDownstream = false;
     }
   }
@@ -377,6 +387,7 @@ public boolean isEmpty() {
 
   @Override
   public void clear() {
+    terminated = true;
     if (DISCARD_GUARD.getAndIncrement(this) != 0) {
       return;
     }
@@ -384,17 +395,12 @@ public void clear() {
     int missed = 1;
 
     for (; ; ) {
-      while (!queue.isEmpty()) {
-        T t = queue.poll();
-        if (t != null) {
-          release(t);
-        }
+      T t;
+      while ((t = queue.poll()) != null) {
+        release(t);
       }
-      while (!priorityQueue.isEmpty()) {
-        T t = priorityQueue.poll();
-        if (t != null) {
-          release(t);
-        }
+      while ((t = priorityQueue.poll()) != null) {
+        release(t);
       }
 
       missed = DISCARD_GUARD.addAndGet(this, -missed);
@@ -415,7 +421,43 @@ public int requestFusion(int requestedMode) {
 
   @Override
   public void dispose() {
-    cancel();
+    if (cancelled) {
+      return;
+    }
+
+    error = new CancellationException("Disposed");
+    done = true;
+
+    boolean once = true;
+    if (WIP.getAndIncrement(this) == 0) {
+      cancelled = true;
+      int m = 1;
+      for (; ; ) {
+        final CoreSubscriber<? super T> a = this.actual;
+
+        if (!outputFused || terminated) {
+          clear();
+        }
+
+        if (a != null && once) {
+          try {
+            a.onError(error);
+          } catch (Throwable ignored) {
+          }
+        }
+
+        cancelled = true;
+        once = false;
+
+        int wip = this.wip;
+        if (wip == m) {
+          break;
+        }
+        m = wip;
+      }
+
+      hasDownstream = false;
+    }
   }
 
   @Override
diff --git a/rsocket-core/src/test/java/io/rsocket/internal/UnboundedProcessorTest.java b/rsocket-core/src/test/java/io/rsocket/internal/UnboundedProcessorTest.java
index 7bf975543..552afb70c 100644
--- a/rsocket-core/src/test/java/io/rsocket/internal/UnboundedProcessorTest.java
+++ b/rsocket-core/src/test/java/io/rsocket/internal/UnboundedProcessorTest.java
@@ -1,5 +1,5 @@
 /*
- * Copyright 2015-2018 the original author or authors.
+ * Copyright 2015-present the original author or authors.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -16,115 +16,173 @@
 
 package io.rsocket.internal;
 
-import io.rsocket.Payload;
-import io.rsocket.util.ByteBufPayload;
-import io.rsocket.util.EmptyPayload;
-import java.util.concurrent.CountDownLatch;
-import org.junit.Assert;
-import org.junit.Test;
+import static org.assertj.core.api.Assertions.assertThat;
+
+import io.netty.buffer.ByteBuf;
+import io.netty.buffer.ByteBufAllocator;
+import io.netty.buffer.Unpooled;
+import io.netty.util.CharsetUtil;
+import io.netty.util.ReferenceCountUtil;
+import io.rsocket.buffer.LeaksTrackingByteBufAllocator;
+import io.rsocket.internal.subscriber.AssertSubscriber;
+import java.time.Duration;
+import org.junit.jupiter.api.BeforeAll;
+import org.junit.jupiter.api.RepeatedTest;
+import org.junit.jupiter.api.Timeout;
+import org.junit.jupiter.params.ParameterizedTest;
+import org.junit.jupiter.params.provider.ValueSource;
+import reactor.core.Fuseable;
+import reactor.core.publisher.Hooks;
+import reactor.core.publisher.Operators;
+import reactor.core.scheduler.Schedulers;
+import reactor.test.StepVerifier;
+import reactor.test.util.RaceTestUtils;
 
 public class UnboundedProcessorTest {
-  @Test
-  public void testOnNextBeforeSubscribe_10() {
-    testOnNextBeforeSubscribeN(10);
-  }
-
-  @Test
-  public void testOnNextBeforeSubscribe_100() {
-    testOnNextBeforeSubscribeN(100);
-  }
 
-  @Test
-  public void testOnNextBeforeSubscribe_10_000() {
-    testOnNextBeforeSubscribeN(10_000);
+  @BeforeAll
+  public static void setup() {
+    Hooks.onErrorDropped(__ -> {});
   }
 
-  @Test
-  public void testOnNextBeforeSubscribe_100_000() {
-    testOnNextBeforeSubscribeN(100_000);
-  }
-
-  @Test
-  public void testOnNextBeforeSubscribe_1_000_000() {
-    testOnNextBeforeSubscribeN(1_000_000);
-  }
-
-  @Test
-  public void testOnNextBeforeSubscribe_10_000_000() {
-    testOnNextBeforeSubscribeN(10_000_000);
+  public static void teardown() {
+    Hooks.resetOnErrorDropped();
   }
 
+  @ParameterizedTest(
+      name =
+          "Test that emitting {0} onNext before subscribe and requestN should deliver all the signals once the subscriber is available")
+  @ValueSource(ints = {10, 100, 10_000, 100_000, 1_000_000, 10_000_000})
   public void testOnNextBeforeSubscribeN(int n) {
-    UnboundedProcessor<Payload> processor = new UnboundedProcessor<>();
+    UnboundedProcessor<ByteBuf> processor = new UnboundedProcessor<>();
 
     for (int i = 0; i < n; i++) {
-      processor.onNext(EmptyPayload.INSTANCE);
+      processor.onNext(Unpooled.EMPTY_BUFFER);
     }
 
     processor.onComplete();
 
-    long count = processor.count().block();
-
-    Assert.assertEquals(n, count);
-  }
-
-  @Test
-  public void testOnNextAfterSubscribe_10() throws Exception {
-    testOnNextAfterSubscribeN(10);
-  }
-
-  @Test
-  public void testOnNextAfterSubscribe_100() throws Exception {
-    testOnNextAfterSubscribeN(100);
+    StepVerifier.create(processor.count()).expectNext(Long.valueOf(n)).verifyComplete();
   }
 
-  @Test
-  public void testOnNextAfterSubscribe_1000() throws Exception {
-    testOnNextAfterSubscribeN(1000);
-  }
+  @ParameterizedTest(
+      name =
+          "Test that emitting {0} onNext after subscribe and requestN should deliver all the signals")
+  @ValueSource(ints = {10, 100, 10_000})
+  public void testOnNextAfterSubscribeN(int n) {
+    UnboundedProcessor<ByteBuf> processor = new UnboundedProcessor<>();
+    AssertSubscriber<ByteBuf> assertSubscriber = AssertSubscriber.create();
 
-  @Test
-  public void testPrioritizedSending() {
-    UnboundedProcessor<Payload> processor = new UnboundedProcessor<>();
+    processor.subscribe(assertSubscriber);
 
-    for (int i = 0; i < 1000; i++) {
-      processor.onNext(EmptyPayload.INSTANCE);
+    for (int i = 0; i < n; i++) {
+      processor.onNext(Unpooled.EMPTY_BUFFER);
     }
 
-    processor.onNextPrioritized(ByteBufPayload.create("test"));
-
-    Payload closestPayload = processor.next().block();
-
-    Assert.assertEquals(closestPayload.getDataUtf8(), "test");
+    assertSubscriber.awaitAndAssertNextValueCount(n);
   }
 
-  @Test
-  public void testPrioritizedFused() {
-    UnboundedProcessor<Payload> processor = new UnboundedProcessor<>();
+  @ParameterizedTest(
+      name =
+          "Test that prioritized value sending deliver prioritized signals before the others mode[fusionEnabled={0}]")
+  @ValueSource(booleans = {true, false})
+  public void testPrioritizedSending(boolean fusedCase) {
+    UnboundedProcessor<ByteBuf> processor = new UnboundedProcessor<>();
 
     for (int i = 0; i < 1000; i++) {
-      processor.onNext(EmptyPayload.INSTANCE);
+      processor.onNext(Unpooled.EMPTY_BUFFER);
     }
 
-    processor.onNextPrioritized(ByteBufPayload.create("test"));
+    processor.onNextPrioritized(Unpooled.copiedBuffer("test", CharsetUtil.UTF_8));
 
-    Payload closestPayload = processor.poll();
-
-    Assert.assertEquals(closestPayload.getDataUtf8(), "test");
+    assertThat(fusedCase ? processor.poll() : processor.next().block())
+        .isNotNull()
+        .extracting(bb -> bb.toString(CharsetUtil.UTF_8))
+        .isEqualTo("test");
   }
 
-  public void testOnNextAfterSubscribeN(int n) throws Exception {
-    CountDownLatch latch = new CountDownLatch(n);
-    UnboundedProcessor<Payload> processor = new UnboundedProcessor<>();
-    processor.log().doOnNext(integer -> latch.countDown()).subscribe();
-
-    for (int i = 0; i < n; i++) {
-      System.out.println("onNexting -> " + i);
-      processor.onNext(EmptyPayload.INSTANCE);
+  @ParameterizedTest(
+      name =
+          "Ensures that racing between onNext | dispose | cancel | request(n) will not cause any issues and leaks; mode[fusionEnabled={0}]")
+  @ValueSource(booleans = {true, false})
+  public void ensureUnboundedProcessorDisposesQueueProperly(boolean withFusionEnabled) {
+    final LeaksTrackingByteBufAllocator allocator =
+        LeaksTrackingByteBufAllocator.instrument(ByteBufAllocator.DEFAULT);
+    for (int i = 0; i < 100000; i++) {
+      final UnboundedProcessor<ByteBuf> unboundedProcessor = new UnboundedProcessor<>();
+
+      final ByteBuf buffer1 = allocator.buffer(1);
+      final ByteBuf buffer2 = allocator.buffer(2);
+
+      final AssertSubscriber<ByteBuf> assertSubscriber =
+          new AssertSubscriber<ByteBuf>(0)
+              .requestedFusionMode(withFusionEnabled ? Fuseable.ANY : Fuseable.NONE);
+
+      unboundedProcessor.subscribe(assertSubscriber);
+
+      RaceTestUtils.race(
+          () ->
+              RaceTestUtils.race(
+                  () ->
+                      RaceTestUtils.race(
+                          () -> {
+                            unboundedProcessor.onNext(buffer1);
+                            unboundedProcessor.onNext(buffer2);
+                          },
+                          unboundedProcessor::dispose,
+                          Schedulers.elastic()),
+                  assertSubscriber::cancel,
+                  Schedulers.elastic()),
+          () -> {
+            assertSubscriber.request(1);
+            assertSubscriber.request(1);
+          },
+          Schedulers.elastic());
+
+      assertSubscriber.values().forEach(ReferenceCountUtil::safeRelease);
+
+      allocator.assertHasNoLeaks();
     }
+  }
 
-    processor.drain();
-
-    latch.await();
+  @RepeatedTest(
+      name =
+          "Ensures that racing between onNext + dispose | downstream async drain should not cause any issues and leaks",
+      value = 100000)
+  @Timeout(60)
+  public void ensuresAsyncFusionAndDisposureHasNoDeadlock() {
+    // TODO: enable leaks tracking
+    //    final LeaksTrackingByteBufAllocator allocator =
+    //        LeaksTrackingByteBufAllocator.instrument(ByteBufAllocator.DEFAULT);
+    final UnboundedProcessor<ByteBuf> unboundedProcessor = new UnboundedProcessor<>();
+
+    //    final ByteBuf buffer1 = allocator.buffer(1);
+    //    final ByteBuf buffer2 = allocator.buffer(2);
+
+    final AssertSubscriber<ByteBuf> assertSubscriber =
+        new AssertSubscriber<>(Operators.enableOnDiscard(null, ReferenceCountUtil::safeRelease));
+
+    unboundedProcessor.publishOn(Schedulers.parallel()).subscribe(assertSubscriber);
+
+    RaceTestUtils.race(
+        () -> {
+          //          unboundedProcessor.onNext(buffer1);
+          //          unboundedProcessor.onNext(buffer2);
+          unboundedProcessor.onNext(Unpooled.EMPTY_BUFFER);
+          unboundedProcessor.onNext(Unpooled.EMPTY_BUFFER);
+          unboundedProcessor.onNext(Unpooled.EMPTY_BUFFER);
+          unboundedProcessor.onNext(Unpooled.EMPTY_BUFFER);
+          unboundedProcessor.onNext(Unpooled.EMPTY_BUFFER);
+          unboundedProcessor.onNext(Unpooled.EMPTY_BUFFER);
+          unboundedProcessor.dispose();
+        },
+        unboundedProcessor::dispose);
+
+    assertSubscriber
+        .await(Duration.ofSeconds(50))
+        .values()
+        .forEach(ReferenceCountUtil::safeRelease);
+
+    //    allocator.assertHasNoLeaks();
   }
 }
diff --git a/rsocket-core/src/test/java/io/rsocket/internal/subscriber/AssertSubscriber.java b/rsocket-core/src/test/java/io/rsocket/internal/subscriber/AssertSubscriber.java
index 84a589a8d..83d420d90 100644
--- a/rsocket-core/src/test/java/io/rsocket/internal/subscriber/AssertSubscriber.java
+++ b/rsocket-core/src/test/java/io/rsocket/internal/subscriber/AssertSubscriber.java
@@ -26,6 +26,7 @@
 import java.util.Set;
 import java.util.concurrent.CountDownLatch;
 import java.util.concurrent.TimeUnit;
+import java.util.concurrent.atomic.AtomicIntegerFieldUpdater;
 import java.util.concurrent.atomic.AtomicLongFieldUpdater;
 import java.util.concurrent.atomic.AtomicReferenceFieldUpdater;
 import java.util.function.BooleanSupplier;
@@ -86,6 +87,10 @@ public class AssertSubscriber<T> implements CoreSubscriber<T>, Subscription {
   private static final AtomicLongFieldUpdater<AssertSubscriber> REQUESTED =
       AtomicLongFieldUpdater.newUpdater(AssertSubscriber.class, "requested");
 
+  @SuppressWarnings("rawtypes")
+  private static final AtomicIntegerFieldUpdater<AssertSubscriber> WIP =
+      AtomicIntegerFieldUpdater.newUpdater(AssertSubscriber.class, "wip");
+
   @SuppressWarnings("rawtypes")
   private static final AtomicReferenceFieldUpdater<AssertSubscriber, List> NEXT_VALUES =
       AtomicReferenceFieldUpdater.newUpdater(AssertSubscriber.class, List.class, "values");
@@ -100,10 +105,14 @@ public class AssertSubscriber<T> implements CoreSubscriber<T>, Subscription {
 
   private final CountDownLatch cdl = new CountDownLatch(1);
 
+  volatile boolean done;
+
   volatile Subscription s;
 
   volatile long requested;
 
+  volatile int wip;
+
   volatile List<T> values = new LinkedList<>();
 
   /** The fusion mode to request. */
@@ -377,7 +386,7 @@ public final AssertSubscriber<T> assertError(Class<? extends Throwable> clazz) {
       }
     }
     if (s > 1) {
-      throw new AssertionError("Multiple errors: " + s, null);
+      throw new AssertionError("Multiple errors: " + errors, null);
     }
     return this;
   }
@@ -854,6 +863,10 @@ public void cancel() {
       a = S.getAndSet(this, Operators.cancelledSubscription());
       if (a != null && a != Operators.cancelledSubscription()) {
         a.cancel();
+
+        if (establishedFusionMode == Fuseable.ASYNC && WIP.getAndIncrement(this) == 0) {
+          qs.clear();
+        }
       }
     }
   }
@@ -868,37 +881,77 @@ public final boolean isTerminated() {
 
   @Override
   public void onComplete() {
+    done = true;
     completionCount++;
+
+    if (establishedFusionMode == Fuseable.ASYNC) {
+      drain();
+      return;
+    }
+
     cdl.countDown();
   }
 
   @Override
   public void onError(Throwable t) {
+    done = true;
     errors.add(t);
+
+    if (establishedFusionMode == Fuseable.ASYNC) {
+      drain();
+      return;
+    }
+
     cdl.countDown();
   }
 
   @Override
   public void onNext(T t) {
     if (establishedFusionMode == Fuseable.ASYNC) {
-      for (; ; ) {
-        t = qs.poll();
-        if (t == null) {
-          break;
-        }
-        valueCount++;
-        if (valuesStorage) {
-          List<T> nextValuesSnapshot;
-          for (; ; ) {
-            nextValuesSnapshot = values;
-            nextValuesSnapshot.add(t);
-            if (NEXT_VALUES.compareAndSet(this, nextValuesSnapshot, nextValuesSnapshot)) {
-              break;
-            }
+      drain();
+    } else {
+      valueCount++;
+      if (valuesStorage) {
+        List<T> nextValuesSnapshot;
+        for (; ; ) {
+          nextValuesSnapshot = values;
+          nextValuesSnapshot.add(t);
+          if (NEXT_VALUES.compareAndSet(this, nextValuesSnapshot, nextValuesSnapshot)) {
+            break;
           }
         }
       }
-    } else {
+    }
+  }
+
+  void drain() {
+    if (this.wip != 0 || WIP.getAndIncrement(this) != 0) {
+      if (isCancelled()) {
+        qs.clear();
+      }
+      return;
+    }
+
+    T t;
+    int m = 1;
+    for (; ; ) {
+      if (isCancelled()) {
+        qs.clear();
+        break;
+      }
+      boolean done = this.done;
+      t = qs.poll();
+      if (t == null) {
+        if (done) {
+          cdl.countDown();
+          return;
+        }
+        m = WIP.addAndGet(this, -m);
+        if (m == 0) {
+          break;
+        }
+        continue;
+      }
       valueCount++;
       if (valuesStorage) {
         List<T> nextValuesSnapshot;