diff --git a/server/http-server.c b/server/http-server.c
index 88ab9c9..21fe812 100644
--- a/server/http-server.c
+++ b/server/http-server.c
@@ -54,6 +54,9 @@
 #define PERM_EXPIRE_TIME 7200       /* 2 hours */
 #define VIRINFO_EXPIRE_TIME 7200       /* 2 hours */
 
+#define FS_ID_LIST_MAX_WORKERS 3
+#define FS_ID_LIST_TOKEN_LEN 36
+
 struct _HttpServer {
     evbase_t *evbase;
     evhtp_t *evhtp;
@@ -69,6 +72,11 @@ struct _HttpServer {
     pthread_mutex_t vir_repo_info_cache_lock;
 
     event_t *reap_timer;
+
+    GThreadPool *compute_fs_obj_id_pool;
+
+    GHashTable *fs_obj_ids;
+    pthread_mutex_t fs_obj_ids_lock;
 };
 typedef struct _HttpServer HttpServer;
 
@@ -115,6 +123,9 @@ const char *GET_HEAD_COMMITS_MULTI_REGEX = "^/repo/head-commits-multi";
 const char *COMMIT_OPER_REGEX = "^/repo/[\\da-z]{8}-[\\da-z]{4}-[\\da-z]{4}-[\\da-z]{4}-[\\da-z]{12}/commit/[\\da-z]{40}";
 const char *PUT_COMMIT_INFO_REGEX = "^/repo/[\\da-z]{8}-[\\da-z]{4}-[\\da-z]{4}-[\\da-z]{4}-[\\da-z]{12}/commit/[\\da-z]{40}";
 const char *GET_FS_OBJ_ID_REGEX = "^/repo/[\\da-z]{8}-[\\da-z]{4}-[\\da-z]{4}-[\\da-z]{4}-[\\da-z]{12}/fs-id-list/.*";
+const char *START_FS_OBJ_ID_REGEX = "^/repo/[\\da-z]{8}-[\\da-z]{4}-[\\da-z]{4}-[\\da-z]{4}-[\\da-z]{12}/start-fs-id-list/.*";
+const char *QUERY_FS_OBJ_ID_REGEX = "^/repo/[\\da-z]{8}-[\\da-z]{4}-[\\da-z]{4}-[\\da-z]{4}-[\\da-z]{12}/query-fs-id-list/.*";
+const char *RETRIEVE_FS_OBJ_ID_REGEX = "^/repo/[\\da-z]{8}-[\\da-z]{4}-[\\da-z]{4}-[\\da-z]{4}-[\\da-z]{12}/retrieve-fs-id-list/.*";
 const char *BLOCK_OPER_REGEX = "^/repo/[\\da-z]{8}-[\\da-z]{4}-[\\da-z]{4}-[\\da-z]{4}-[\\da-z]{12}/block/[\\da-z]{40}";
 const char *POST_CHECK_FS_REGEX = "^/repo/[\\da-z]{8}-[\\da-z]{4}-[\\da-z]{4}-[\\da-z]{4}-[\\da-z]{12}/check-fs";
 const char *POST_CHECK_BLOCK_REGEX = "^/repo/[\\da-z]{8}-[\\da-z]{4}-[\\da-z]{4}-[\\da-z]{4}-[\\da-z]{12}/check-blocks";
@@ -1531,6 +1542,293 @@ out:
     seaf_repo_unref (repo);
 }
 
+typedef struct ComputeObjTask {
+    HttpServer *htp_server;
+    char *token;
+    char *repo_id;
+    char *client_head;
+    char *server_head;
+    gboolean dir_only;
+} ComputeObjTask;
+
+typedef struct CalObjResult {
+    GList *list;
+    gboolean done;
+} CalObjResult;
+
+static void
+free_compute_obj_task(ComputeObjTask *task)
+{
+    if (!task)
+        return;
+
+    if (task->token)
+        g_free(task->token);
+    if (task->repo_id)
+        g_free(task->repo_id);
+    if (task->client_head)
+        g_free(task->client_head);
+    if (task->server_head)
+        g_free(task->server_head);
+    g_free(task);
+}
+
+static void
+free_obj_cal_result (gpointer data)
+{
+    CalObjResult *result = (CalObjResult *)data;
+    if (!result)
+        return;
+
+    if (result->list)
+        g_list_free (result->list);
+
+    g_free(result);
+}
+
+static void
+compute_fs_obj_id (gpointer ptask, gpointer ppara)
+{
+    SeafRepo *repo = NULL;
+    ComputeObjTask *task = ptask;
+    const char *client_head = task->client_head;
+    const char *server_head = task->server_head;
+    char *repo_id = task->repo_id;
+    gboolean dir_only = task->dir_only;
+    HttpServer *htp_server = task->htp_server;
+    CalObjResult *result = NULL;
+
+    pthread_mutex_lock (&htp_server->fs_obj_ids_lock);
+    result = g_hash_table_lookup (htp_server->fs_obj_ids, task->token);
+    pthread_mutex_unlock (&htp_server->fs_obj_ids_lock);
+    if (!result) {
+        goto out;
+    }
+
+    repo = seaf_repo_manager_get_repo (seaf->repo_mgr, repo_id);
+    if (!repo) {
+        seaf_warning ("Failed to find repo %.8s.\n", repo_id);
+        goto out;
+    }
+
+    if (calculate_send_object_list (repo, server_head, client_head, dir_only, &result->list) < 0) {
+        pthread_mutex_lock (&htp_server->fs_obj_ids_lock);
+        g_hash_table_remove (htp_server->fs_obj_ids, task->token);
+        pthread_mutex_unlock (&htp_server->fs_obj_ids_lock);
+        goto out;
+    }
+
+    result->done = TRUE;
+out:
+    seaf_repo_unref (repo);
+    free_compute_obj_task(task);
+}
+
+static void
+start_fs_obj_id_cb (evhtp_request_t *req, void *arg)
+{
+    HttpServer *htp_server = arg;
+    char **parts;
+    char *repo_id;
+    gboolean dir_only = FALSE;
+    json_t *obj;
+
+    const char *server_head = evhtp_kv_find (req->uri->query, "server-head");
+    if (server_head == NULL || !is_object_id_valid (server_head)) {
+        char *error = "Invalid server-head parameter.\n";
+        evbuffer_add (req->buffer_out, error, strlen (error));
+        evhtp_send_reply (req, EVHTP_RES_BADREQ);
+        return;
+    }
+
+    const char *client_head = evhtp_kv_find (req->uri->query, "client-head");
+    if (client_head && !is_object_id_valid (client_head)) {
+        char *error = "Invalid client-head parameter.\n";
+        evbuffer_add (req->buffer_out, error, strlen (error));
+        evhtp_send_reply (req, EVHTP_RES_BADREQ);
+        return;
+    }
+
+    const char *dir_only_arg = evhtp_kv_find (req->uri->query, "dir-only");
+    if (dir_only_arg)
+        dir_only = TRUE;
+
+    parts = g_strsplit (req->uri->path->full + 1, "/", 0);
+    repo_id = parts[1];
+
+    int token_status = validate_token (htp_server, req, repo_id, NULL, FALSE);
+    if (token_status != EVHTP_RES_OK) {
+        evhtp_send_reply (req, token_status);
+        goto out;
+    }
+
+    char uuid[37];
+    char *new_token;
+    gen_uuid_inplace (uuid);
+    new_token = g_strndup(uuid, FS_ID_LIST_TOKEN_LEN);
+
+    CalObjResult *result = g_new0(CalObjResult, 1);
+    if (!result) {
+        evhtp_send_reply (req, EVHTP_RES_SERVERR);
+        goto out;
+    }
+    result->done = FALSE;
+
+    ComputeObjTask *task = g_new0 (ComputeObjTask, 1);
+    if (!task) {
+        evhtp_send_reply (req, EVHTP_RES_SERVERR);
+        goto out;
+    }
+
+    task->token = new_token;
+    task->dir_only = dir_only;
+    task->htp_server = htp_server;
+    task->repo_id = g_strdup(repo_id);
+    task->client_head = g_strdup(client_head);
+    task->server_head = g_strdup(server_head);
+
+    pthread_mutex_lock (&htp_server->fs_obj_ids_lock);
+    g_hash_table_insert (htp_server->fs_obj_ids, g_strdup(task->token), result);
+    pthread_mutex_unlock (&htp_server->fs_obj_ids_lock);
+    g_thread_pool_push (htp_server->compute_fs_obj_id_pool, task, NULL);
+    obj = json_object ();
+    json_object_set_new (obj, "token", json_string (new_token));
+
+    char *json_str = json_dumps (obj, JSON_COMPACT);
+    evbuffer_add (req->buffer_out, json_str, strlen(json_str));
+    evhtp_send_reply (req, EVHTP_RES_OK);
+
+    g_free (json_str);
+    json_decref (obj);
+out:
+    g_strfreev (parts);
+}
+
+static void
+query_fs_obj_id_cb (evhtp_request_t *req, void *arg)
+{
+    json_t *obj;
+    const char *token = NULL;
+    CalObjResult *result = NULL;
+    char **parts;
+    char *repo_id = NULL;
+    HttpServer *htp_server = (HttpServer *)arg;
+
+    parts = g_strsplit (req->uri->path->full + 1, "/", 0);
+    repo_id = parts[1];
+
+    int token_status = validate_token (htp_server, req, repo_id, NULL, FALSE);
+    if (token_status != EVHTP_RES_OK) {
+        evhtp_send_reply (req, token_status);
+        goto out;
+    }
+
+    token = evhtp_kv_find (req->uri->query, "token");
+    if (!token || strlen(token)!=FS_ID_LIST_TOKEN_LEN) {
+        evhtp_send_reply (req, EVHTP_RES_BADREQ);
+        goto out;
+    }
+
+    obj = json_object ();
+
+    pthread_mutex_lock (&htp_server->fs_obj_ids_lock);
+    result = g_hash_table_lookup (htp_server->fs_obj_ids, token);
+    if (!result) {
+        pthread_mutex_unlock (&htp_server->fs_obj_ids_lock);
+        evhtp_send_reply (req, EVHTP_RES_NOTFOUND);
+        goto out;
+    } else {
+        if (!result->done) {
+            json_object_set_new (obj, "success", json_false());
+        } else {
+            json_object_set_new (obj, "success", json_true());
+        }
+    }
+    pthread_mutex_unlock (&htp_server->fs_obj_ids_lock);
+
+    json_object_set_new (obj, "token", json_string (token));
+
+    char *json_str = json_dumps (obj, JSON_COMPACT);
+    evbuffer_add (req->buffer_out, json_str, strlen(json_str));
+    evhtp_send_reply (req, EVHTP_RES_OK);
+
+    g_free (json_str);
+
+out:
+    if (obj)
+        json_decref (obj);
+    g_strfreev (parts);
+    return;
+}
+
+static void
+retrieve_fs_obj_id_cb (evhtp_request_t *req, void *arg)
+{
+    char **parts;
+    const char *token = NULL;
+    char *repo_id = NULL;
+    GList *list = NULL;
+    CalObjResult *result = NULL;
+    HttpServer *htp_server = (HttpServer *)arg;
+
+    parts = g_strsplit (req->uri->path->full + 1, "/", 0);
+    repo_id = parts[1];
+
+    int token_status = validate_token (htp_server, req, repo_id, NULL, FALSE);
+    if (token_status != EVHTP_RES_OK) {
+        evhtp_send_reply (req, token_status);
+        goto out;
+    }
+
+    token = evhtp_kv_find (req->uri->query, "token");
+    if (!token || strlen(token)!=FS_ID_LIST_TOKEN_LEN) {
+        evhtp_send_reply (req, EVHTP_RES_BADREQ);
+        goto out;
+    }
+
+    pthread_mutex_lock (&htp_server->fs_obj_ids_lock);
+    result = g_hash_table_lookup (htp_server->fs_obj_ids, token);
+    if (!result) {
+        pthread_mutex_unlock (&htp_server->fs_obj_ids_lock);
+        evhtp_send_reply (req, EVHTP_RES_NOTFOUND);
+
+        return;
+    }
+    if (!result->done) {
+        pthread_mutex_unlock (&htp_server->fs_obj_ids_lock);
+
+        char *error = "The cauculation task is not completed.\n";
+        evbuffer_add (req->buffer_out, error, strlen(error));
+        evhtp_send_reply (req, EVHTP_RES_BADREQ);
+        return;
+    }
+    list = result->list;
+    pthread_mutex_unlock (&htp_server->fs_obj_ids_lock);
+
+    GList *ptr;
+    json_t *obj_array = json_array ();
+
+    for (ptr = list; ptr; ptr = ptr->next) {
+        json_array_append_new (obj_array, json_string (ptr->data));
+        g_free (ptr->data);
+    }
+
+    pthread_mutex_lock (&htp_server->fs_obj_ids_lock);
+    g_hash_table_remove (htp_server->fs_obj_ids, token);
+    pthread_mutex_unlock (&htp_server->fs_obj_ids_lock);
+
+    char *obj_list = json_dumps (obj_array, JSON_COMPACT);
+    evbuffer_add (req->buffer_out, obj_list, strlen (obj_list));
+    evhtp_send_reply (req, EVHTP_RES_OK);
+
+    g_free (obj_list);
+    json_decref (obj_array);
+
+out:
+    g_strfreev (parts);
+    return;
+}
+
 static void
 get_block_cb (evhtp_request_t *req, void *arg)
 {
@@ -2346,6 +2644,18 @@ http_request_init (HttpServerStruct *server)
                         GET_FS_OBJ_ID_REGEX, get_fs_obj_id_cb,
                         priv);
 
+    evhtp_set_regex_cb (priv->evhtp,
+                        START_FS_OBJ_ID_REGEX, start_fs_obj_id_cb,
+                        priv);
+
+    evhtp_set_regex_cb (priv->evhtp,
+                        QUERY_FS_OBJ_ID_REGEX, query_fs_obj_id_cb,
+                        priv);
+
+    evhtp_set_regex_cb (priv->evhtp,
+                        RETRIEVE_FS_OBJ_ID_REGEX, retrieve_fs_obj_id_cb,
+                        priv);
+
     evhtp_set_regex_cb (priv->evhtp,
                         BLOCK_OPER_REGEX, block_oper_cb,
                         priv);
@@ -2530,6 +2840,13 @@ seaf_http_server_new (struct _SeafileSession *session)
 
     server->http_temp_dir = g_build_filename (session->seaf_dir, "httptemp", NULL);
 
+    priv->compute_fs_obj_id_pool = g_thread_pool_new (compute_fs_obj_id, NULL,
+                                                      FS_ID_LIST_MAX_WORKERS, FALSE, NULL);
+
+    priv->fs_obj_ids = g_hash_table_new_full (g_str_hash, g_str_equal,
+                                              g_free, free_obj_cal_result);
+    pthread_mutex_init (&priv->fs_obj_ids_lock, NULL);
+
     server->seaf_session = session;
     server->priv = priv;