diff --git a/core/store/primitives/src/main/java/org/onosproject/store/primitives/resources/impl/AtomixWorkQueue.java b/core/store/primitives/src/main/java/org/onosproject/store/primitives/resources/impl/AtomixWorkQueue.java
new file mode 100644
index 0000000..7b4ad47
--- /dev/null
+++ b/core/store/primitives/src/main/java/org/onosproject/store/primitives/resources/impl/AtomixWorkQueue.java
@@ -0,0 +1,201 @@
+/*
+ * Copyright 2016-present Open Networking Laboratory
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package org.onosproject.store.primitives.resources.impl;
+
+import static org.slf4j.LoggerFactory.getLogger;
+
+import java.util.Collection;
+import java.util.List;
+import java.util.Properties;
+import java.util.Timer;
+import java.util.concurrent.CompletableFuture;
+import java.util.concurrent.Executor;
+import java.util.concurrent.ExecutorService;
+import java.util.concurrent.Executors;
+import java.util.concurrent.atomic.AtomicBoolean;
+import java.util.concurrent.atomic.AtomicInteger;
+import java.util.concurrent.atomic.AtomicReference;
+import java.util.function.Consumer;
+
+import org.onlab.util.AbstractAccumulator;
+import org.onlab.util.Accumulator;
+import org.onosproject.store.primitives.resources.impl.AtomixWorkQueueCommands.Add;
+import org.onosproject.store.primitives.resources.impl.AtomixWorkQueueCommands.Complete;
+import org.onosproject.store.primitives.resources.impl.AtomixWorkQueueCommands.Register;
+import org.onosproject.store.primitives.resources.impl.AtomixWorkQueueCommands.Stats;
+import org.onosproject.store.primitives.resources.impl.AtomixWorkQueueCommands.Take;
+import org.onosproject.store.primitives.resources.impl.AtomixWorkQueueCommands.Unregister;
+import org.onosproject.store.service.WorkQueue;
+import org.onosproject.store.service.Task;
+import org.onosproject.store.service.WorkQueueStats;
+import org.slf4j.Logger;
+
+import com.google.common.collect.ImmutableList;
+
+import io.atomix.copycat.client.CopycatClient;
+import io.atomix.resource.AbstractResource;
+import io.atomix.resource.ResourceTypeInfo;
+
+/**
+ * Distributed resource providing the {@link WorkQueue} primitive.
+ */
+@ResourceTypeInfo(id = -154, factory = AtomixWorkQueueFactory.class)
+public class AtomixWorkQueue extends AbstractResource<AtomixWorkQueue>
+    implements WorkQueue<byte[]> {
+
+    private final Logger log = getLogger(getClass());
+    public static final String TASK_AVAILABLE = "task-available";
+    private final ExecutorService executor = Executors.newSingleThreadExecutor();
+    private final AtomicReference<TaskProcessor> taskProcessor = new AtomicReference<>();
+    private final Timer timer = new Timer("atomix-work-queue-completer");
+    private final AtomicBoolean isRegistered = new AtomicBoolean(false);
+
+    protected AtomixWorkQueue(CopycatClient client, Properties options) {
+        super(client, options);
+    }
+
+    @Override
+    public CompletableFuture<AtomixWorkQueue> open() {
+        return super.open().thenApply(result -> {
+            client.onStateChange(state -> {
+                if (state == CopycatClient.State.CONNECTED && isRegistered.get()) {
+                    client.submit(new Register());
+                }
+            });
+            client.onEvent(TASK_AVAILABLE, this::resumeWork);
+            return result;
+        });
+    }
+
+    @Override
+    public CompletableFuture<Void> addMultiple(Collection<byte[]> items) {
+        if (items.isEmpty()) {
+            return CompletableFuture.completedFuture(null);
+        }
+        return client.submit(new Add(items));
+    }
+
+    @Override
+    public CompletableFuture<Collection<Task<byte[]>>> take(int maxTasks) {
+        if (maxTasks <= 0) {
+            return CompletableFuture.completedFuture(ImmutableList.of());
+        }
+        return client.submit(new Take(maxTasks));
+    }
+
+    @Override
+    public CompletableFuture<Void> complete(Collection<String> taskIds) {
+        if (taskIds.isEmpty()) {
+            return CompletableFuture.completedFuture(null);
+        }
+        return client.submit(new Complete(taskIds));
+    }
+
+    @Override
+    public CompletableFuture<Void> registerTaskProcessor(Consumer<byte[]> callback,
+                                          int parallelism,
+                                          Executor executor) {
+        Accumulator<String> completedTaskAccumulator =
+                new CompletedTaskAccumulator(timer, 50, 50); // TODO: make configurable
+        taskProcessor.set(new TaskProcessor(callback,
+                                            parallelism,
+                                            executor,
+                                            completedTaskAccumulator));
+        return register().thenCompose(v -> take(parallelism))
+                         .thenAccept(taskProcessor.get()::accept);
+    }
+
+    @Override
+    public CompletableFuture<Void> stopProcessing() {
+        return unregister();
+    }
+
+    @Override
+    public CompletableFuture<WorkQueueStats> stats() {
+        return client.submit(new Stats());
+    }
+
+    private void resumeWork() {
+        TaskProcessor activeProcessor = taskProcessor.get();
+        if (activeProcessor == null) {
+            return;
+        }
+        this.take(activeProcessor.headRoom())
+            .whenCompleteAsync((tasks, e) -> activeProcessor.accept(tasks), executor);
+    }
+
+    private CompletableFuture<Void> register() {
+        return client.submit(new Register()).thenRun(() -> isRegistered.set(true));
+    }
+
+    private CompletableFuture<Void> unregister() {
+        return client.submit(new Unregister()).thenRun(() -> isRegistered.set(false));
+    }
+
+    // TaskId accumulator for paced triggering of task completion calls.
+    private class CompletedTaskAccumulator extends AbstractAccumulator<String> {
+        CompletedTaskAccumulator(Timer timer, int maxTasksToBatch, int maxBatchMillis) {
+            super(timer, maxTasksToBatch, maxBatchMillis, Integer.MAX_VALUE);
+        }
+
+        @Override
+        public void processItems(List<String> items) {
+            complete(items);
+        }
+    }
+
+    private class TaskProcessor implements Consumer<Collection<Task<byte[]>>> {
+
+        private final AtomicInteger headRoom;
+        private final Consumer<byte[]> backingConsumer;
+        private final Executor executor;
+        private final Accumulator<String> taskCompleter;
+
+        public TaskProcessor(Consumer<byte[]> backingConsumer,
+                             int parallelism,
+                             Executor executor,
+                             Accumulator<String> taskCompleter) {
+            this.backingConsumer = backingConsumer;
+            this.headRoom = new AtomicInteger(parallelism);
+            this.executor = executor;
+            this.taskCompleter = taskCompleter;
+        }
+
+        public int headRoom() {
+            return headRoom.get();
+        }
+
+        @Override
+        public void accept(Collection<Task<byte[]>> tasks) {
+            if (tasks == null) {
+                return;
+            }
+            headRoom.addAndGet(-1 * tasks.size());
+            tasks.forEach(task ->
+                executor.execute(() -> {
+                    try {
+                        backingConsumer.accept(task.payload());
+                        taskCompleter.add(task.taskId());
+                    } catch (Exception e) {
+                        log.debug("Task execution failed", e);
+                    } finally {
+                        headRoom.incrementAndGet();
+                        resumeWork();
+                    }
+                }));
+        }
+    }
+}
diff --git a/core/store/primitives/src/main/java/org/onosproject/store/primitives/resources/impl/AtomixWorkQueueCommands.java b/core/store/primitives/src/main/java/org/onosproject/store/primitives/resources/impl/AtomixWorkQueueCommands.java
new file mode 100644
index 0000000..3724529
--- /dev/null
+++ b/core/store/primitives/src/main/java/org/onosproject/store/primitives/resources/impl/AtomixWorkQueueCommands.java
@@ -0,0 +1,224 @@
+/*
+ * Copyright 2016-present Open Networking Laboratory
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package org.onosproject.store.primitives.resources.impl;
+
+import java.util.ArrayList;
+import java.util.Collection;
+import java.util.stream.Collectors;
+import java.util.stream.IntStream;
+
+import org.onosproject.store.service.Task;
+import org.onosproject.store.service.WorkQueueStats;
+
+import com.google.common.base.MoreObjects;
+
+import io.atomix.catalyst.buffer.BufferInput;
+import io.atomix.catalyst.buffer.BufferOutput;
+import io.atomix.catalyst.serializer.CatalystSerializable;
+import io.atomix.catalyst.serializer.SerializableTypeResolver;
+import io.atomix.catalyst.serializer.Serializer;
+import io.atomix.catalyst.serializer.SerializerRegistry;
+import io.atomix.copycat.Command;
+
+/**
+ * {@link AtomixWorkQueue} resource state machine operations.
+ */
+public final class AtomixWorkQueueCommands {
+
+    private AtomixWorkQueueCommands() {
+    }
+
+    /**
+     * Command to add a collection of tasks to the queue.
+     */
+    @SuppressWarnings("serial")
+    public static class Add implements Command<Void>, CatalystSerializable {
+
+        private Collection<byte[]> items;
+
+        private Add() {
+        }
+
+        public Add(Collection<byte[]> items) {
+            this.items = items;
+        }
+
+        @Override
+        public void writeObject(BufferOutput<?> buffer, Serializer serializer) {
+            buffer.writeInt(items.size());
+            items.forEach(task -> serializer.writeObject(task, buffer));
+        }
+
+        @Override
+        public void readObject(BufferInput<?> buffer, Serializer serializer) {
+            items = IntStream.range(0, buffer.readInt())
+                             .mapToObj(i -> serializer.<byte[]>readObject(buffer))
+                             .collect(Collectors.toCollection(ArrayList::new));
+        }
+
+        public Collection<byte[]> items() {
+            return items;
+        }
+
+        @Override
+        public String toString() {
+            return MoreObjects.toStringHelper(getClass())
+                    .add("items", items)
+                    .toString();
+        }
+    }
+
+    /**
+     * Command to take a task from the queue.
+     */
+    @SuppressWarnings("serial")
+    public static class Take implements Command<Collection<Task<byte[]>>>, CatalystSerializable {
+
+        private int maxTasks;
+
+        private Take() {
+        }
+
+        public Take(int maxTasks) {
+            this.maxTasks = maxTasks;
+        }
+
+        @Override
+        public void writeObject(BufferOutput<?> buffer, Serializer serializer) {
+            buffer.writeInt(maxTasks);
+        }
+
+        @Override
+        public void readObject(BufferInput<?> buffer, Serializer serializer) {
+            maxTasks = buffer.readInt();
+        }
+
+        public int maxTasks() {
+            return maxTasks;
+        }
+
+        @Override
+        public String toString() {
+            return MoreObjects.toStringHelper(getClass())
+                    .add("maxTasks", maxTasks)
+                    .toString();
+        }
+    }
+
+    @SuppressWarnings("serial")
+    public static class Stats implements Command<WorkQueueStats>, CatalystSerializable {
+
+        @Override
+        public void writeObject(BufferOutput<?> buffer, Serializer serializer) {
+        }
+
+        @Override
+        public void readObject(BufferInput<?> buffer, Serializer serializer) {
+        }
+
+        @Override
+        public String toString() {
+            return MoreObjects.toStringHelper(getClass())
+                    .toString();
+        }
+    }
+
+
+
+    @SuppressWarnings("serial")
+    public static class Register implements Command<Void>, CatalystSerializable {
+
+        @Override
+        public void writeObject(BufferOutput<?> buffer, Serializer serializer) {
+        }
+
+        @Override
+        public void readObject(BufferInput<?> buffer, Serializer serializer) {
+        }
+
+        @Override
+        public String toString() {
+            return MoreObjects.toStringHelper(getClass())
+                    .toString();
+        }
+    }
+
+    @SuppressWarnings("serial")
+    public static class Unregister implements Command<Void>, CatalystSerializable {
+
+        @Override
+        public void writeObject(BufferOutput<?> buffer, Serializer serializer) {
+        }
+
+        @Override
+        public void readObject(BufferInput<?> buffer, Serializer serializer) {
+        }
+
+        @Override
+        public String toString() {
+            return MoreObjects.toStringHelper(getClass())
+                    .toString();
+        }
+    }
+
+    @SuppressWarnings("serial")
+    public static class Complete implements Command<Void>, CatalystSerializable {
+        private Collection<String> taskIds;
+
+        private Complete() {
+        }
+
+        public Complete(Collection<String> taskIds) {
+            this.taskIds = taskIds;
+        }
+
+        @Override
+        public void writeObject(BufferOutput<?> buffer, Serializer serializer) {
+            serializer.writeObject(taskIds, buffer);
+        }
+
+        @Override
+        public void readObject(BufferInput<?> buffer, Serializer serializer) {
+            taskIds = serializer.readObject(buffer);
+        }
+
+        public Collection<String> taskIds() {
+            return taskIds;
+        }
+
+        @Override
+        public String toString() {
+            return MoreObjects.toStringHelper(getClass())
+                    .add("taskIds", taskIds)
+                    .toString();
+        }
+    }
+
+    /**
+     * Work queue command type resolver.
+     */
+    public static class TypeResolver implements SerializableTypeResolver {
+        @Override
+        public void resolve(SerializerRegistry registry) {
+            registry.register(Register.class, -960);
+            registry.register(Unregister.class, -961);
+            registry.register(Take.class, -962);
+            registry.register(Add.class, -963);
+            registry.register(Complete.class, -964);
+            registry.register(Stats.class, -965);
+        }
+    }
+}
diff --git a/core/store/primitives/src/main/java/org/onosproject/store/primitives/resources/impl/AtomixWorkQueueFactory.java b/core/store/primitives/src/main/java/org/onosproject/store/primitives/resources/impl/AtomixWorkQueueFactory.java
new file mode 100644
index 0000000..0c61b2e
--- /dev/null
+++ b/core/store/primitives/src/main/java/org/onosproject/store/primitives/resources/impl/AtomixWorkQueueFactory.java
@@ -0,0 +1,44 @@
+/*
+ * Copyright 2016-present Open Networking Laboratory
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package org.onosproject.store.primitives.resources.impl;
+
+import io.atomix.catalyst.serializer.SerializableTypeResolver;
+import io.atomix.copycat.client.CopycatClient;
+import io.atomix.resource.ResourceFactory;
+import io.atomix.resource.ResourceStateMachine;
+
+import java.util.Properties;
+
+/**
+ * {@link AtomixWorkQueue} resource factory.
+ */
+public class AtomixWorkQueueFactory implements ResourceFactory<AtomixWorkQueue> {
+
+    @Override
+    public SerializableTypeResolver createSerializableTypeResolver() {
+        return new AtomixWorkQueueCommands.TypeResolver();
+    }
+
+    @Override
+    public ResourceStateMachine createStateMachine(Properties config) {
+        return new AtomixWorkQueueState(config);
+    }
+
+    @Override
+    public AtomixWorkQueue createInstance(CopycatClient client, Properties properties) {
+        return new AtomixWorkQueue(client, properties);
+    }
+}
\ No newline at end of file
diff --git a/core/store/primitives/src/main/java/org/onosproject/store/primitives/resources/impl/AtomixWorkQueueState.java b/core/store/primitives/src/main/java/org/onosproject/store/primitives/resources/impl/AtomixWorkQueueState.java
new file mode 100644
index 0000000..d287e19
--- /dev/null
+++ b/core/store/primitives/src/main/java/org/onosproject/store/primitives/resources/impl/AtomixWorkQueueState.java
@@ -0,0 +1,289 @@
+/*
+ * Copyright 2016-present Open Networking Laboratory
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package org.onosproject.store.primitives.resources.impl;
+
+import static org.slf4j.LoggerFactory.getLogger;
+
+import java.util.ArrayList;
+import java.util.Collection;
+import java.util.Iterator;
+import java.util.Map;
+import java.util.Properties;
+import java.util.Queue;
+import java.util.concurrent.atomic.AtomicInteger;
+import java.util.concurrent.atomic.AtomicLong;
+import java.util.function.Consumer;
+import java.util.stream.Collectors;
+import java.util.stream.IntStream;
+
+import org.onlab.util.CountDownCompleter;
+import org.onosproject.store.primitives.resources.impl.AtomixWorkQueueCommands.Add;
+import org.onosproject.store.primitives.resources.impl.AtomixWorkQueueCommands.Complete;
+import org.onosproject.store.primitives.resources.impl.AtomixWorkQueueCommands.Register;
+import org.onosproject.store.primitives.resources.impl.AtomixWorkQueueCommands.Stats;
+import org.onosproject.store.primitives.resources.impl.AtomixWorkQueueCommands.Take;
+import org.onosproject.store.primitives.resources.impl.AtomixWorkQueueCommands.Unregister;
+import org.onosproject.store.service.Task;
+import org.onosproject.store.service.WorkQueueStats;
+import org.slf4j.Logger;
+
+import com.google.common.base.MoreObjects;
+import com.google.common.base.Throwables;
+import com.google.common.collect.ImmutableList;
+import com.google.common.collect.Maps;
+import com.google.common.collect.Queues;
+import com.google.common.util.concurrent.AtomicLongMap;
+
+import io.atomix.copycat.server.Commit;
+import io.atomix.copycat.server.Snapshottable;
+import io.atomix.copycat.server.StateMachineExecutor;
+import io.atomix.copycat.server.session.ServerSession;
+import io.atomix.copycat.server.session.SessionListener;
+import io.atomix.copycat.server.storage.snapshot.SnapshotReader;
+import io.atomix.copycat.server.storage.snapshot.SnapshotWriter;
+import io.atomix.resource.ResourceStateMachine;
+
+/**
+ * State machine for {@link AtomixWorkQueue} resource.
+ */
+public class AtomixWorkQueueState  extends ResourceStateMachine implements SessionListener, Snapshottable {
+
+    private final Logger log = getLogger(getClass());
+
+    private final AtomicLong totalCompleted = new AtomicLong(0);
+
+    private final Queue<TaskHolder> unassignedTasks = Queues.newArrayDeque();
+    private final Map<String, TaskAssignment> assignments = Maps.newHashMap();
+    private final Map<Long, Commit<? extends Register>> registeredWorkers = Maps.newHashMap();
+    private final AtomicLongMap<Long> activeTasksPerSession = AtomicLongMap.create();
+
+    protected AtomixWorkQueueState(Properties config) {
+        super(config);
+    }
+
+    @Override
+    protected void configure(StateMachineExecutor executor) {
+        executor.register(Stats.class, this::stats);
+        executor.register(Register.class, (Consumer<Commit<Register>>) this::register);
+        executor.register(Unregister.class, (Consumer<Commit<Unregister>>) this::unregister);
+        executor.register(Add.class, (Consumer<Commit<Add>>) this::add);
+        executor.register(Take.class, this::take);
+        executor.register(Complete.class, (Consumer<Commit<Complete>>) this::complete);
+    }
+
+    protected WorkQueueStats stats(Commit<? extends Stats> commit) {
+        try {
+            return WorkQueueStats.builder()
+                    .withTotalCompleted(totalCompleted.get())
+                    .withTotalPending(unassignedTasks.size())
+                    .withTotalInProgress(assignments.size())
+                    .build();
+        } finally {
+            commit.close();
+        }
+    }
+
+    protected void register(Commit<? extends Register> commit) {
+        long sessionId = commit.session().id();
+        if (registeredWorkers.putIfAbsent(sessionId, commit) != null) {
+            commit.close();
+        }
+    }
+
+    protected void unregister(Commit<? extends Unregister> commit) {
+        try {
+            Commit<? extends Register> registerCommit = registeredWorkers.remove(commit.session().id());
+            if (registerCommit != null) {
+                registerCommit.close();
+            }
+        } finally {
+            commit.close();
+        }
+    }
+
+    protected void add(Commit<? extends Add> commit) {
+        Collection<byte[]> items = commit.operation().items();
+
+        // Create a CountDownCompleter that will close the commit when all tasks
+        // submitted as part of it are completed.
+        CountDownCompleter<Commit<? extends Add>> referenceTracker =
+                new CountDownCompleter<>(commit, items.size(), Commit::close);
+
+        AtomicInteger itemIndex = new AtomicInteger(0);
+        items.forEach(item -> {
+            String taskId = String.format("%d:%d:%d", commit.session().id(),
+                                                      commit.index(),
+                                                      itemIndex.getAndIncrement());
+            unassignedTasks.add(new TaskHolder(new Task<>(taskId, item), referenceTracker));
+        });
+
+        // Send an event to all sessions that have expressed interest in task processing
+        // and are not actively processing a task.
+        registeredWorkers.values()
+                         .stream()
+                         .map(Commit::session)
+                         .forEach(session -> session.publish(AtomixWorkQueue.TASK_AVAILABLE));
+        // FIXME: This generates a lot of event traffic.
+    }
+
+    protected Collection<Task<byte[]>> take(Commit<? extends Take> commit) {
+        try {
+            if (unassignedTasks.isEmpty()) {
+                return ImmutableList.of();
+            }
+            long sessionId = commit.session().id();
+            int maxTasks = commit.operation().maxTasks();
+            return IntStream.range(0, Math.min(maxTasks, unassignedTasks.size()))
+                            .mapToObj(i -> {
+                                TaskHolder holder = unassignedTasks.poll();
+                                String taskId = holder.task().taskId();
+                                TaskAssignment assignment = new TaskAssignment(sessionId, holder);
+
+                                // bookkeeping
+                                assignments.put(taskId, assignment);
+                                activeTasksPerSession.incrementAndGet(sessionId);
+
+                                return holder.task();
+                            })
+                            .collect(Collectors.toCollection(ArrayList::new));
+        } catch (Exception e) {
+            log.warn("State machine update failed", e);
+            throw Throwables.propagate(e);
+        } finally {
+            commit.close();
+        }
+    }
+
+    protected void complete(Commit<? extends Complete> commit) {
+        long sessionId = commit.session().id();
+        try {
+            commit.operation().taskIds().forEach(taskId -> {
+                TaskAssignment assignment = assignments.get(taskId);
+                if (assignment != null) {
+                    assignments.remove(taskId).markComplete();
+                    // bookkeeping
+                    totalCompleted.incrementAndGet();
+                    activeTasksPerSession.decrementAndGet(sessionId);
+                }
+            });
+        } catch (Exception e) {
+            log.warn("State machine update failed", e);
+            throw Throwables.propagate(e);
+        } finally {
+            commit.close();
+        }
+    }
+
+    @Override
+    public void register(ServerSession session) {
+    }
+
+    @Override
+    public void unregister(ServerSession session) {
+        evictWorker(session.id());
+    }
+
+    @Override
+    public void expire(ServerSession session) {
+        evictWorker(session.id());
+    }
+
+    @Override
+    public void close(ServerSession session) {
+        evictWorker(session.id());
+    }
+
+    @Override
+    public void snapshot(SnapshotWriter writer) {
+        writer.writeLong(totalCompleted.get());
+    }
+
+    @Override
+    public void install(SnapshotReader reader) {
+        totalCompleted.set(reader.readLong());
+    }
+
+    private void evictWorker(long sessionId) {
+        Commit<? extends Register> commit = registeredWorkers.remove(sessionId);
+        if (commit != null) {
+            commit.close();
+        }
+
+        // TODO: Maintain an index of tasks by session for efficient access.
+        Iterator<Map.Entry<String, TaskAssignment>> iter = assignments.entrySet().iterator();
+        while (iter.hasNext()) {
+            Map.Entry<String, TaskAssignment> entry = iter.next();
+            TaskAssignment assignment = entry.getValue();
+            if (assignment.sessionId() == sessionId) {
+                unassignedTasks.add(assignment.taskHolder());
+                iter.remove();
+            }
+        }
+
+        // Bookkeeping
+        activeTasksPerSession.remove(sessionId);
+        activeTasksPerSession.removeAllZeros();
+    }
+
+    private class TaskHolder {
+
+        private final Task<byte[]> task;
+        private final CountDownCompleter<Commit<? extends Add>> referenceTracker;
+
+        public TaskHolder(Task<byte[]> delegate, CountDownCompleter<Commit<? extends Add>> referenceTracker) {
+            this.task = delegate;
+            this.referenceTracker = referenceTracker;
+        }
+
+        public Task<byte[]> task() {
+            return task;
+        }
+
+        public void complete() {
+            referenceTracker.countDown();
+        }
+    }
+
+    private class TaskAssignment {
+        private final long sessionId;
+        private final TaskHolder taskHolder;
+
+        public TaskAssignment(long sessionId, TaskHolder taskHolder) {
+            this.sessionId = sessionId;
+            this.taskHolder = taskHolder;
+        }
+
+        public long sessionId() {
+            return sessionId;
+        }
+
+        public TaskHolder taskHolder() {
+            return taskHolder;
+        }
+
+        public void markComplete() {
+            taskHolder.complete();
+        }
+
+        @Override
+        public String toString() {
+            return MoreObjects.toStringHelper(getClass())
+                              .add("sessionId", sessionId)
+                              .add("taskHolder", taskHolder)
+                              .toString();
+        }
+    }
+}