diff --git a/ui/code-owners-api.js b/ui/code-owners-api.js
new file mode 100644
index 0000000..408428b
--- /dev/null
+++ b/ui/code-owners-api.js
@@ -0,0 +1,183 @@
+/**
+ * @license
+ * Copyright (C) 2021 The Android Open Source Project
+ *
+ * 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.
+ */
+
+
+// TODO: Try to remove it. The ResponseError and getErrorMessage duplicates
+// code from the gr-plugin-rest-api.ts. This code is required because
+// we want custom error processing in some functions. For details see
+// the original gr-plugin-rest-api.ts file/
+
+class ResponseError extends Error {
+  constructor(response) {
+    super();
+    this.response = response;
+  }
+}
+
+async function getErrorMessage(response) {
+  const text = await response.text();
+  return text ?
+    `${response.status}: ${text}` :
+    `${response.status}`;
+}
+
+/**
+ * Responsible for communicating with the rest-api
+ *
+ * @see resources/Documentation/rest-api.md
+ */
+export class CodeOwnersApi {
+  constructor(restApi) {
+    this.restApi = restApi;
+  }
+
+  /**
+   * Returns a promise fetching the owner statuses for all files within the change.
+   *
+   * @doc https://gerrit.googlesource.com/plugins/code-owners/+/refs/heads/master/resources/Documentation/rest-api.md#change-endpoints
+   * @param {string} changeId
+   */
+  listOwnerStatus(changeId) {
+    return this.restApi.get(`/changes/${changeId}/code_owners.status`);
+  }
+
+  /**
+   * Returns a promise fetching the owners for a given path.
+   *
+   * @doc https://gerrit.googlesource.com/plugins/code-owners/+/refs/heads/master/resources/Documentation/rest-api.md#list-code-owners-for-path-in-branch
+   * @param {string} changeId
+   * @param {string} path
+   */
+  listOwnersForPath(changeId, path, limit) {
+    return this.restApi.get(
+        `/changes/${changeId}/revisions/current/code_owners` +
+        `/${encodeURIComponent(path)}?limit=${limit}&o=DETAILS`
+    );
+  }
+
+  /**
+   * Returns a promise fetching the owners config for a given path.
+   *
+   * @doc https://gerrit.googlesource.com/plugins/code-owners/+/refs/heads/master/resources/Documentation/rest-api.md#branch-endpoints
+   * @param {string} project
+   * @param {string} branch
+   * @param {string} path
+   */
+  getConfigForPath(project, branch, path) {
+    return this.restApi.get(
+        `/projects/${encodeURIComponent(project)}/` +
+        `branches/${encodeURIComponent(branch)}/` +
+        `code_owners.config/${encodeURIComponent(path)}`
+    );
+  }
+
+  /**
+   * Returns a promise fetching the owners config for a given branch.
+   *
+   * @doc https://gerrit.googlesource.com/plugins/code-owners/+/refs/heads/master/resources/Documentation/rest-api.md#branch-endpoints
+   * @param {string} project
+   * @param {string} branch
+   */
+  async getBranchConfig(project, branch) {
+    const errFn = (response, error) => {
+      if (error) throw error;
+      if (response) throw new ResponseError(response);
+      throw new Error('Generic REST API error');
+    }
+    try {
+      const config = await this.restApi.send(
+          'GET',
+          `/projects/${encodeURIComponent(project)}/` +
+          `branches/${encodeURIComponent(branch)}/` +
+          `code_owners.branch_config`,
+          undefined,
+          errFn
+      );
+      if (config.override_approval && !(config.override_approval
+          instanceof Array)) {
+        // In the upcoming backend changes, the override_approval will be changed
+        // to array with (possible) multiple items.
+        // While this transition is in progress, the frontend supports both API -
+        // the old one and the new one.
+        return {...config, override_approval: [config.override_approval]};
+      }
+      return config;
+    } catch(err) {
+      if (err instanceof ResponseError) {
+        if (err.response.status === 404) {
+          // The 404 error means that the branch doesn't exist and
+          // the plugin should be disabled.
+          return {disabled: true};
+        }
+        return getErrorMessage(err.response).then(msg => {
+          throw new Error(msg);
+        });
+      }
+      throw err;
+    }
+  }
+}
+
+/**
+ * Wrapper around codeOwnerApi, sends each requests only once and then cache
+ * the response. A new CodeOwnersCacheApi instance is created every time when a
+ * new change object is assigned.
+ * Gerrit never updates existing change object, but instead always assigns a new
+ * change object. Particularly, a new change object is assigned when a change
+ * is updated and user clicks reload toasts to see the updated change.
+ * As a result, the lifetime of a cache is the same as a lifetime of an assigned
+ * change object.
+ * Periodical cache invalidation can lead to inconsistency in UI, i.e.
+ * user can see the old reviewers list (reflects a state when a change was
+ * loaded) and code-owners status for the current reviewer list. To avoid
+ * this inconsistency, the cache doesn't invalidate.
+ */
+export class CodeOwnersCacheApi {
+  constructor(codeOwnerApi, change) {
+    this.codeOwnerApi = codeOwnerApi;
+    this.change = change;
+    this.promises = {};
+  }
+
+  _fetchOnce(cacheKey, asyncFn) {
+    if (!this.promises[cacheKey]) {
+      this.promises[cacheKey] = asyncFn();
+    }
+    return this.promises[cacheKey];
+  }
+
+  getAccount() {
+    return this._fetchOnce('getAccount', () => this._getAccount());
+  }
+
+  async _getAccount() {
+    const loggedIn = await this.codeOwnerApi.restApi.getLoggedIn();
+    if (!loggedIn) return undefined;
+    return await this.codeOwnerApi.restApi.getAccount();
+  }
+
+  listOwnerStatus() {
+    return this._fetchOnce('listOwnerStatus',
+        () => this.codeOwnerApi.listOwnerStatus(this.change._number));
+  }
+
+  getBranchConfig() {
+    return this._fetchOnce('getBranchConfig',
+        () => this.codeOwnerApi.getBranchConfig(this.change.project,
+            this.change.branch));
+  }
+}
diff --git a/ui/code-owners-fetcher.js b/ui/code-owners-fetcher.js
new file mode 100644
index 0000000..61e362b
--- /dev/null
+++ b/ui/code-owners-fetcher.js
@@ -0,0 +1,204 @@
+/**
+ * @license
+ * Copyright (C) 2021 The Android Open Source Project
+ *
+ * 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.
+ */
+
+import {CodeOwnersApi} from './code-owners-api.js';
+
+/**
+ * All statuses returned for owner status.
+ *
+ * @enum
+ */
+export const OwnerStatus = {
+  INSUFFICIENT_REVIEWERS: 'INSUFFICIENT_REVIEWERS',
+  PENDING: 'PENDING',
+  APPROVED: 'APPROVED',
+};
+
+/**
+ * @enum
+ */
+export const FetchStatus = {
+  /** Fetch hasn't been started */
+  NOT_STARTED: 0,
+  /**
+   * Fetch has been started, but not all files has been finished.
+   * Pausing during fetching doesn't change state.
+   */
+  FETCHING: 1,
+  /**
+   * All owners has been loaded. resume/pause call doesn't change state.
+   */
+  FINISHED: 2,
+};
+
+/**
+ * Fetch owners for files. The class fetches owners in parallel and allows to
+ * pause/resume fetch.
+ */
+class OwnersFetcher {
+  /**
+   * Creates a fetcher in paused state. Actual fetching starts after resume()
+   * is called.
+   *
+   * @param {Array<string>} filesToFetch - Files paths for loading owners.
+   * @param {number} ownersLimit - number of requested owners per file.
+   * @param {number} maxConcurrentRequest - max number of concurrent requests to server.
+   */
+  constructor(codeOwnerApi, changeId, filesToFetch, ownersLimit,
+      maxConcurrentRequest) {
+    this._fetchedOwners = new Map();
+    this._ownersLimit = ownersLimit;
+    this._paused = true;
+    this._pausedFilesFetcher = [];
+    this._filesToFetch = filesToFetch;
+    this._fetchFilesPromises = [];
+    this._codeOwnerApi = codeOwnerApi;
+    this._changeId = changeId;
+
+    for (let i = 0; i < maxConcurrentRequest; i++) {
+      this._fetchFilesPromises.push(this._fetchFiles());
+    }
+  }
+
+  async _fetchFiles() {
+    for (;;) {
+      const filePath = await this._getNextFilePath();
+      if (!filePath) return;
+      try {
+        this._fetchedOwners.set(filePath, {
+          owners: await this._codeOwnerApi.listOwnersForPath(this._changeId,
+              filePath, this._ownersLimit),
+        });
+      } catch (error) {
+        this._fetchedOwners.set(filePath, {error});
+      }
+    }
+  }
+
+  async _getNextFilePath() {
+    if (this._paused) {
+      await new Promise(resolve => this._pausedFilesFetcher.push(resolve));
+    }
+    if (this._filesToFetch.length === 0) return null;
+    return this._filesToFetch.splice(0, 1)[0];
+  }
+
+  async waitFetchComplete() {
+    await Promise.allSettled(this._fetchFilesPromises);
+  }
+
+  resume() {
+    if (!this._paused) return;
+    this._paused = false;
+    for (const fetcher of this._pausedFilesFetcher.splice(0,
+        this._pausedFilesFetcher.length)) {
+      fetcher();
+    }
+  }
+
+  pause() {
+    this._paused = true;
+  }
+
+  getFetchedOwners() {
+    return this._fetchedOwners;
+  }
+
+  getFiles() {
+    const result = [];
+    for (const [path, info] of this._fetchedOwners.entries()) {
+      result.push({path, info});
+    }
+    return result;
+  }
+}
+
+export class OwnersProvider {
+  constructor(restApi, change, options) {
+    this.change = change;
+    this.options = options;
+    this._totalFetchCount = 0;
+    this._status = FetchStatus.NOT_STARTED;
+    this._codeOwnerApi = new CodeOwnersApi(restApi);
+  }
+
+  getStatus() {
+    return this._status;
+  }
+
+  getProgressString() {
+    return !this._ownersFetcher || this._totalFetchCount === 0 ?
+      `Loading suggested owners ...` :
+      `${this._ownersFetcher.getFetchedOwners().size} out of ` +
+      `${this._totalFetchCount} files have returned suggested owners.`;
+  }
+
+  getFiles() {
+    if (!this._ownersFetcher) return [];
+    return this._ownersFetcher.getFiles();
+  }
+
+  async fetchSuggestedOwners(codeOwnerStatusMap) {
+    if (this._status !== FetchStatus.NOT_STARTED) {
+      await this._ownersFetcher.waitFetchComplete();
+      return;
+    }
+    const filesToFetch = this._getFilesToFetch(codeOwnerStatusMap);
+    this._totalFetchCount = filesToFetch.length;
+    this._ownersFetcher = new OwnersFetcher(this._codeOwnerApi, this.change.id,
+        filesToFetch,
+        this.options.ownersLimit, this.options.maxConcurrentRequests);
+    this._status = FetchStatus.FETCHING;
+    this._ownersFetcher.resume();
+    await this._ownersFetcher.waitFetchComplete(filesToFetch);
+    this._status = FetchStatus.FINISHED;
+  }
+
+  _getFilesToFetch(codeOwnerStatusMap) {
+    // only fetch those not approved yet
+    const filesGroupByStatus = [...codeOwnerStatusMap.keys()].reduce(
+        (list, file) => {
+          const status = codeOwnerStatusMap
+              .get(file).status;
+          if (status === OwnerStatus.INSUFFICIENT_REVIEWERS) {
+            list.missing.push(file);
+          } else if (status === OwnerStatus.PENDING) {
+            list.pending.push(file);
+          }
+          return list;
+        }
+        , {pending: [], missing: []});
+    // always fetch INSUFFICIENT_REVIEWERS first and then pending
+    return filesGroupByStatus.missing.concat(filesGroupByStatus.pending);
+  }
+
+  pause() {
+    if (!this._ownersFetcher) return;
+    this._ownersFetcher.pause();
+  }
+
+  resume() {
+    if (!this._ownersFetcher) return;
+    this._ownersFetcher.resume();
+  }
+
+  reset() {
+    this._totalFetchCount = 0;
+    this.ownersFetcher = null;
+    this._status = FetchStatus.NOT_STARTED;
+  }
+}
diff --git a/ui/code-owners-model-loader.js b/ui/code-owners-model-loader.js
index 0e5ace7..2fa18ac 100644
--- a/ui/code-owners-model-loader.js
+++ b/ui/code-owners-model-loader.js
@@ -39,6 +39,7 @@
     try {
       newValue = await propertyLoader();
     } catch (e) {
+      console.error(e);
       this.ownersModel.setPluginFailed(e.message);
       return;
     }
@@ -85,6 +86,14 @@
   }
 
   async loadSuggestions(suggestionsType) {
+    this.pauseActiveSuggestedOwnersLoading();
+    this.activeLoadSuggestionType = suggestionsType;
+    if (this.ownersModel.suggestionsByTypes[suggestionsType].state ===
+        SuggestionsState.Loading) {
+      this.ownersService.resumeSuggestedOwnersLoading(suggestionsType);
+      return;
+    }
+
     // If a loading has been started already, do nothing
     if (this.ownersModel.suggestionsByTypes[suggestionsType].state !==
         SuggestionsState.NotLoaded) return;
@@ -96,6 +105,7 @@
       suggestedOwners =
           await this.ownersService.getSuggestedOwners(suggestionsType);
     } catch (e) {
+      console.error(e);
       this.ownersModel.setSuggestionsState(suggestionsType,
           SuggestionsState.LoadFailed);
       // The selectedSuggestionsType can be changed while getSuggestedOwners
@@ -112,6 +122,12 @@
         SuggestionsState.Loaded);
   }
 
+  pauseActiveSuggestedOwnersLoading() {
+    if (!this.activeLoadSuggestionType) return;
+    this.ownersService.pauseSuggestedOwnersLoading(
+        this.activeLoadSuggestionType);
+  }
+
   async updateLoadSelectedSuggestionsProgress() {
     const suggestionsType = this.ownersModel.selectedSuggestionsType;
     let suggestedOwners;
diff --git a/ui/code-owners-model-mixin.js b/ui/code-owners-model-mixin.js
index 722af6f..80c8ffb 100644
--- a/ui/code-owners-model-mixin.js
+++ b/ui/code-owners-model-mixin.js
@@ -37,6 +37,7 @@
        */
       this.modelLoader = undefined;
     }
+
     static get properties() {
       return {
         /* The following 3 properties (change, reporting, restApi) have to be
diff --git a/ui/code-owners-service.js b/ui/code-owners-service.js
index 55ad38a..0db6226 100644
--- a/ui/code-owners-service.js
+++ b/ui/code-owners-service.js
@@ -16,27 +16,8 @@
  */
 
 import {SuggestionsType, BestSuggestionsLimit, AllSuggestionsLimit} from './code-owners-model.js';
-
-/**
- * All statuses returned for owner status.
- *
- * @enum
- */
-export const OwnerStatus = {
-  INSUFFICIENT_REVIEWERS: 'INSUFFICIENT_REVIEWERS',
-  PENDING: 'PENDING',
-  APPROVED: 'APPROVED',
-};
-
-/**
- * @enum
- */
-const FetchStatus = {
-  NOT_STARTED: 0,
-  FETCHING: 1,
-  FINISHED: 2,
-  ABORT: 3,
-};
+import {OwnersProvider, OwnerStatus, FetchStatus} from './code-owners-fetcher.js';
+import {CodeOwnersApi, CodeOwnersCacheApi} from './code-owners-api.js';
 
 /**
  * Specifies status for a change. The same as ChangeStatus enum in gerrit
@@ -62,273 +43,6 @@
   OTHER: 'OTHER',
 };
 
-// TODO: Try to remove it. The ResponseError and getErrorMessage duplicates
-// code from the gr-plugin-rest-api.ts. This code is required because
-// we want custom error processing in some functions. For details see
-// the original gr-plugin-rest-api.ts file/
-
-class ResponseError extends Error {
-  constructor(response) {
-    super();
-    this.response = response;
-  }
-}
-
-async function getErrorMessage(response) {
-  const text = await response.text();
-  return text ?
-    `${response.status}: ${text}` :
-    `${response.status}`;
-}
-
-/**
- * Responsible for communicating with the rest-api
- *
- * @see resources/Documentation/rest-api.md
- */
-class CodeOwnerApi {
-  constructor(restApi) {
-    this.restApi = restApi;
-  }
-
-  /**
-   * Returns a promise fetching the owner statuses for all files within the change.
-   *
-   * @doc https://gerrit.googlesource.com/plugins/code-owners/+/refs/heads/master/resources/Documentation/rest-api.md#change-endpoints
-   * @param {string} changeId
-   */
-  listOwnerStatus(changeId) {
-    return this.restApi.get(`/changes/${changeId}/code_owners.status`);
-  }
-
-  /**
-   * Returns a promise fetching the owners for a given path.
-   *
-   * @doc https://gerrit.googlesource.com/plugins/code-owners/+/refs/heads/master/resources/Documentation/rest-api.md#list-code-owners-for-path-in-branch
-   * @param {string} changeId
-   * @param {string} path
-   */
-  listOwnersForPath(changeId, path, limit) {
-    return this.restApi.get(
-        `/changes/${changeId}/revisions/current/code_owners` +
-        `/${encodeURIComponent(path)}?limit=${limit}&o=DETAILS`
-    );
-  }
-
-  /**
-   * Returns a promise fetching the owners config for a given path.
-   *
-   * @doc https://gerrit.googlesource.com/plugins/code-owners/+/refs/heads/master/resources/Documentation/rest-api.md#branch-endpoints
-   * @param {string} project
-   * @param {string} branch
-   * @param {string} path
-   */
-  getConfigForPath(project, branch, path) {
-    return this.restApi.get(
-        `/projects/${encodeURIComponent(project)}/` +
-        `branches/${encodeURIComponent(branch)}/` +
-        `code_owners.config/${encodeURIComponent(path)}`
-    );
-  }
-
-  /**
-   * Returns a promise fetching the owners config for a given branch.
-   *
-   * @doc https://gerrit.googlesource.com/plugins/code-owners/+/refs/heads/master/resources/Documentation/rest-api.md#branch-endpoints
-   * @param {string} project
-   * @param {string} branch
-   */
-  async getBranchConfig(project, branch) {
-    const errFn = (response, error) => {
-      if (error) throw error;
-      if (response) throw new ResponseError(response);
-      throw new Error('Generic REST API error');
-    }
-    try {
-      const config = await this.restApi.send(
-          'GET',
-          `/projects/${encodeURIComponent(project)}/` +
-          `branches/${encodeURIComponent(branch)}/` +
-          `code_owners.branch_config`,
-          undefined,
-          errFn
-      );
-      if (config.override_approval && !(config.override_approval
-          instanceof Array)) {
-        // In the upcoming backend changes, the override_approval will be changed
-        // to array with (possible) multiple items.
-        // While this transition is in progress, the frontend supports both API -
-        // the old one and the new one.
-        return {...config, override_approval: [config.override_approval]};
-      }
-      return config;
-    } catch(err) {
-      if (err instanceof ResponseError) {
-        if (err.response.status === 404) {
-          // The 404 error means that the branch doesn't exist and
-          // the plugin should be disabled.
-          return {disabled: true};
-        }
-        return getErrorMessage(err.response).then(msg => {
-          throw new Error(msg);
-        });
-      }
-      throw err;
-    }
-  }
-}
-
-/**
- * Wrapper around codeOwnerApi, sends each requests only once and then cache
- * the response. A new CodeOwnersCacheApi instance is created every time when a
- * new change object is assigned.
- * Gerrit never updates existing change object, but instead always assigns a new
- * change object. Particularly, a new change object is assigned when a change
- * is updated and user clicks reload toasts to see the updated change.
- * As a result, the lifetime of a cache is the same as a lifetime of an assigned
- * change object.
- * Periodical cache invalidation can lead to inconsistency in UI, i.e.
- * user can see the old reviewers list (reflects a state when a change was
- * loaded) and code-owners status for the current reviewer list. To avoid
- * this inconsistency, the cache doesn't invalidate.
- */
-export class CodeOwnersCacheApi {
-  constructor(codeOwnerApi, change) {
-    this.codeOwnerApi = codeOwnerApi;
-    this.change = change;
-    this.promises = {};
-  }
-
-  _fetchOnce(cacheKey, asyncFn) {
-    if (!this.promises[cacheKey]) {
-      this.promises[cacheKey] = asyncFn();
-    }
-    return this.promises[cacheKey];
-  }
-
-  getAccount() {
-    return this._fetchOnce('getAccount', () => this._getAccount());
-  }
-
-  async _getAccount() {
-    const loggedIn = await this.codeOwnerApi.restApi.getLoggedIn();
-    if (!loggedIn) return undefined;
-    return await this.codeOwnerApi.restApi.getAccount();
-  }
-
-  listOwnerStatus() {
-    return this._fetchOnce('listOwnerStatus',
-        () => this.codeOwnerApi.listOwnerStatus(this.change._number));
-  }
-
-  getBranchConfig() {
-    return this._fetchOnce('getBranchConfig',
-        () => this.codeOwnerApi.getBranchConfig(this.change.project,
-            this.change.branch));
-  }
-}
-
-export class OwnersFetcher {
-  constructor(restApi, change, options) {
-    // fetched files and fetching status
-    this._fetchedOwners = new Map();
-    this._fetchStatus = FetchStatus.NOT_STARTED;
-    this._totalFetchCount = 0;
-    this.change = change;
-    this.options = options;
-    this.codeOwnerApi = new CodeOwnerApi(restApi);
-  }
-
-  getStatus() {
-    return this._fetchStatus;
-  }
-
-  getProgressString() {
-    return this._totalFetchCount === 0 ?
-      `Loading suggested owners ...` :
-      `${this._fetchedOwners.size} out of ${this._totalFetchCount} files have returned suggested owners.`;
-  }
-
-  getFiles() {
-    const result = [];
-    for (const [path, info] of this._fetchedOwners.entries()) {
-      result.push({path, info});
-    }
-    return result;
-  }
-
-  async fetchSuggestedOwners(codeOwnerStatusMap) {
-    // reset existing temporary storage
-    this._fetchedOwners = new Map();
-    this._fetchStatus = FetchStatus.FETCHING;
-    this._totalFetchCount = 0;
-
-    // only fetch those not approved yet
-    const filesGroupByStatus = [...codeOwnerStatusMap.keys()].reduce(
-        (list, file) => {
-          const status = codeOwnerStatusMap
-              .get(file).status;
-          if (status === OwnerStatus.INSUFFICIENT_REVIEWERS) {
-            list.missing.push(file);
-          } else if (status === OwnerStatus.PENDING) {
-            list.pending.push(file);
-          }
-          return list;
-        }
-        , {pending: [], missing: []});
-    // always fetch INSUFFICIENT_REVIEWERS first and then pending
-    const filesToFetch = filesGroupByStatus.missing
-        .concat(filesGroupByStatus.pending);
-    this._totalFetchCount = filesToFetch.length;
-    await this._batchFetchCodeOwners(filesToFetch);
-    this._fetchStatus = FetchStatus.FINISHED;
-  }
-
-  /**
-   * Recursively fetches code owners for all files until finished.
-   *
-   * @param {!Array<string>} files
-   */
-  async _batchFetchCodeOwners(files) {
-    if (this._fetchStatus === FetchStatus.ABORT) {
-      return this._fetchedOwners;
-    }
-
-    const batchRequests = [];
-    const maxConcurrentRequests = this.options.maxConcurrentRequests;
-    for (let i = 0; i < maxConcurrentRequests; i++) {
-      const filePath = files[i];
-      if (filePath) {
-        this._fetchedOwners.set(filePath, {});
-        batchRequests.push(this._fetchOwnersForPath(this.change.id, filePath));
-      }
-    }
-    const resPromise = Promise.all(batchRequests);
-    await resPromise;
-    if (files.length > maxConcurrentRequests) {
-      return await this._batchFetchCodeOwners(
-          files.slice(maxConcurrentRequests));
-    }
-    return this._fetchedOwners;
-  }
-
-  async _fetchOwnersForPath(changeId, filePath) {
-    try {
-      const owners = await this.codeOwnerApi.listOwnersForPath(changeId,
-          filePath, this.options.ownersLimit);
-      this._fetchedOwners.get(filePath).owners = owners;
-    } catch (e) {
-      this._fetchedOwners.get(filePath).error = e;
-    }
-  }
-
-  abort() {
-    this._fetchStatus = FetchStatus.ABORT;
-    this._fetchedOwners = new Map();
-    this._totalFetchCount = 0;
-  }
-}
-
 /**
  * Service for the data layer used in the plugin UI.
  */
@@ -336,19 +50,19 @@
   constructor(restApi, change, options = {}) {
     this.restApi = restApi;
     this.change = change;
-    const codeOwnerApi = new CodeOwnerApi(restApi);
-    this.codeOwnerCacheApi = new CodeOwnersCacheApi(codeOwnerApi, change);
+    const codeOwnersApi = new CodeOwnersApi(restApi);
+    this.codeOwnersCacheApi = new CodeOwnersCacheApi(codeOwnersApi, change);
 
-    const fetcherOptions = {
+    const providerOptions = {
       maxConcurrentRequests: options.maxConcurrentRequests || 10,
     };
-    this.ownersFetchers = {
-      [SuggestionsType.BEST_SUGGESTIONS]: new OwnersFetcher(restApi, change, {
-        ...fetcherOptions,
+    this.ownersProviders = {
+      [SuggestionsType.BEST_SUGGESTIONS]: new OwnersProvider(restApi, change, {
+        ...providerOptions,
         ownersLimit: BestSuggestionsLimit,
       }),
-      [SuggestionsType.ALL_SUGGESTIONS]: new OwnersFetcher(restApi, change, {
-        ...fetcherOptions,
+      [SuggestionsType.ALL_SUGGESTIONS]: new OwnersProvider(restApi, change, {
+        ...providerOptions,
         ownersLimit: AllSuggestionsLimit,
       }),
     };
@@ -360,7 +74,7 @@
   async prefetch() {
     try {
       await Promise.all([
-        this.codeOwnerCacheApi.getAccount(),
+        this.codeOwnersCacheApi.getAccount(),
         this.getStatus(),
       ]);
     } catch {
@@ -377,7 +91,7 @@
    * role 'REVIEWER' remains unchanged until the change view is reloaded.
    */
   async getLoggedInUserInitialRole() {
-    const account = await this.codeOwnerCacheApi.getAccount();
+    const account = await this.codeOwnersCacheApi.getAccount();
     if (!account) {
       return UserRole.ANONYMOUS;
     }
@@ -424,9 +138,9 @@
     const status = await this._getStatus();
     if (status.enabled && !this.isOnLatestPatchset(status.patchsetNumber)) {
       // status is outdated, abort and re-init
-      this.abort();
+      this.reset();
       this.prefetch();
-      return await this.codeOwnerCacheApi.getStatus();
+      return await this.codeOwnersCacheApi.getStatus();
     }
     return status;
   }
@@ -442,7 +156,7 @@
       };
     }
 
-    const onwerStatus = await this.codeOwnerCacheApi.listOwnerStatus();
+    const onwerStatus = await this.codeOwnersCacheApi.listOwnerStatus();
 
     return {
       enabled: true,
@@ -484,39 +198,40 @@
    */
   async getSuggestedOwners(suggestionsType) {
     const {codeOwnerStatusMap} = await this.getStatus();
-    const ownersFetcher = this.ownersFetchers[suggestionsType];
+    const ownersProvider = this.ownersProviders[suggestionsType];
 
-    // In case its aborted due to outdated patches
-    // should kick start the fetching again
-    // Note: we currently are not reusing the instance when switching changes,
-    // so if its `abort` due to different changes, the whole instance will be
-    // outdated and not used.
-    if (ownersFetcher.getStatus() === FetchStatus.NOT_STARTED
-      || ownersFetcher.getStatus() === FetchStatus.ABORT) {
-      await ownersFetcher.fetchSuggestedOwners(codeOwnerStatusMap);
-    }
+    await ownersProvider.fetchSuggestedOwners(codeOwnerStatusMap);
 
     return {
-      finished: ownersFetcher.getStatus() === FetchStatus.FINISHED,
-      status: ownersFetcher.getStatus(),
-      progress: ownersFetcher.getProgressString(),
+      finished: ownersProvider.getStatus() === FetchStatus.FINISHED,
+      status: ownersProvider.getStatus(),
+      progress: ownersProvider.getProgressString(),
       files: this._getFilesWithStatuses(codeOwnerStatusMap,
-          ownersFetcher.getFiles()),
+          ownersProvider.getFiles()),
     };
   }
 
   async getSuggestedOwnersProgress(suggestionsType) {
     const {codeOwnerStatusMap} = await this.getStatus();
-    const ownersFetcher = this.ownersFetchers[suggestionsType];
+    const ownersProvider = this.ownersProviders[suggestionsType];
     return {
-      finished: ownersFetcher.getStatus() === FetchStatus.FINISHED,
-      status: ownersFetcher.getStatus(),
-      progress: ownersFetcher.getProgressString(),
+      finished: ownersProvider.getStatus() === FetchStatus.FINISHED,
+      status: ownersProvider.getStatus(),
+      progress: ownersProvider.getProgressString(),
       files: this._getFilesWithStatuses(codeOwnerStatusMap,
-          ownersFetcher.getFiles()),
+          ownersProvider.getFiles()),
     };
   }
 
+  pauseSuggestedOwnersLoading(suggestionsType) {
+    this.ownersProviders[suggestionsType].pause();
+  }
+
+  resumeSuggestedOwnersLoading(suggestionsType) {
+    this.ownersProviders[suggestionsType].resume();
+  }
+
+
   _formatStatuses(statuses) {
     // convert the array of statuses to map between file path -> status
     return statuses.reduce((prev, cur) => {
@@ -565,16 +280,16 @@
     return `${latestRevision._number}` === `${patchsetId}`;
   }
 
-  abort() {
-    for (const fetcher of Object.values(this.ownersFetchers)) {
-      fetcher.abort();
+  reset() {
+    for (const provider of Object.values(this.ownersProviders)) {
+      provider.reset();
     }
-    const codeOwnerApi = new CodeOwnerApi(this.restApi);
-    this.codeOwnerCacheApi = new CodeOwnersCacheApi(codeOwnerApi, change);
+    const codeOwnersApi = new CodeOwnersApi(this.restApi);
+    this.codeOwnersCacheApi = new CodeOwnersCacheApi(codeOwnersApi, change);
   }
 
   async getBranchConfig() {
-    return this.codeOwnerCacheApi.getBranchConfig();
+    return this.codeOwnersCacheApi.getBranchConfig();
   }
 
   async isCodeOwnerEnabled() {
@@ -582,7 +297,7 @@
         this.change.status === ChangeStatus.MERGED) {
       return false;
     }
-    const config = await this.codeOwnerCacheApi.getBranchConfig();
+    const config = await this.codeOwnersCacheApi.getBranchConfig();
     return config && !config.disabled;
   }
 
diff --git a/ui/owner-requirement.js b/ui/owner-requirement.js
index 1ad5b4b..b506a8b 100644
--- a/ui/owner-requirement.js
+++ b/ui/owner-requirement.js
@@ -15,7 +15,7 @@
  * limitations under the License.
  */
 
-import {OwnerStatus} from './code-owners-service.js';
+import {OwnerStatus} from './code-owners-fetcher.js';
 import {CodeOwnersModelMixin} from './code-owners-model-mixin.js';
 import {showPluginFailedMessage} from './code-owners-banner.js';
 import {PluginState} from './code-owners-model.js';
diff --git a/ui/owner-status-column.js b/ui/owner-status-column.js
index b3d92fb..4e6e055 100644
--- a/ui/owner-status-column.js
+++ b/ui/owner-status-column.js
@@ -15,7 +15,7 @@
  * limitations under the License.
  */
 
-import {OwnerStatus} from './code-owners-service.js';
+import {OwnerStatus} from './code-owners-fetcher.js';
 import {CodeOwnersModelMixin} from './code-owners-model-mixin.js';
 
 const MAGIC_FILES = ['/COMMIT_MSG', '/MERGE_LIST', '/PATCHSET_LEVEL'];
diff --git a/ui/suggest-owners.js b/ui/suggest-owners.js
index 4f9553a..a442421 100644
--- a/ui/suggest-owners.js
+++ b/ui/suggest-owners.js
@@ -404,6 +404,14 @@
     }
   }
 
+  disconnectedCallback() {
+    super.disconnectedCallback();
+    this._stopUpdateProgressTimer();
+    if (this.modelLoader) {
+      this.modelLoader.pauseActiveSuggestedOwnersLoading();
+    }
+  }
+
   _onShowSuggestionsChanged(showSuggestions) {
     if (!showSuggestions) {
       return;
@@ -416,11 +424,11 @@
     // Can not use `this.async` as it's only available in
     // legacy element mixin which not used in this plugin.
     Polymer.Async.timeOut.run(() => this.click(), 100);
-
   }
 
   _onShowSuggestionsTypeChanged(showSuggestion, selectedSuggestionsType) {
     if (!showSuggestion) {
+      this.modelLoader.pauseActiveSuggestedOwnersLoading();
       return;
     }
     this.modelLoader.loadSuggestions(selectedSuggestionsType);
@@ -437,11 +445,6 @@
     }
   }
 
-  disconnectedCallback() {
-    super.disconnectedCallback();
-    this._stopUpdateProgressTimer();
-  }
-
   _startUpdateProgressTimer() {
     if (this._progressUpdateTimer) return;
     this._progressUpdateTimer = setInterval(() => {
@@ -541,21 +544,28 @@
     const res = {};
     res.groupName = suggestion.groupName;
     res.files = suggestion.files.slice();
-    const codeOwners = (suggestion.owners.code_owners || []).map(owner => {
-      const updatedOwner = {...owner};
-      const reviewers = this.change.reviewers.REVIEWER;
-      if (
-        reviewers &&
-        reviewers.find(reviewer => reviewer._account_id === owner._account_id)
-      ) {
-        updatedOwner.selected = true;
-      }
-      return updatedOwner;
-    });
-    res.owners = {
-      owned_by_all_users: !!suggestion.owners.owned_by_all_users,
-      code_owners: codeOwners,
-    };
+    if (suggestion.owners) {
+      const codeOwners = (suggestion.owners.code_owners || []).map(owner => {
+        const updatedOwner = {...owner};
+        const reviewers = this.change.reviewers.REVIEWER;
+        if (reviewers &&
+            reviewers.find(
+                reviewer => reviewer._account_id === owner._account_id)
+        ) {
+          updatedOwner.selected = true;
+        }
+        return updatedOwner;
+      });
+      res.owners = {
+        owned_by_all_users: !!suggestion.owners.owned_by_all_users,
+        code_owners: codeOwners,
+      };
+    } else {
+      res.owners = {
+        owned_by_all_users: false,
+        code_owners: [],
+      };
+    }
 
     res.error = suggestion.error;
     return res;