diff --git a/src/harness/unittests/compileOnSave.ts b/src/harness/unittests/compileOnSave.ts
index fde83170f3..24fd47ee0c 100644
--- a/src/harness/unittests/compileOnSave.ts
+++ b/src/harness/unittests/compileOnSave.ts
@@ -3,6 +3,10 @@
 /// <reference path="../../server/typingsInstaller/typingsInstaller.ts" />
 
 namespace ts.projectSystem {
+    function createTestTypingsInstaller(host: server.ServerHost) {
+        return new TestTypingsInstaller("/a/data/", /*throttleLimit*/5, host);
+    }
+
     describe("CompileOnSave affected list", () => {
         function sendAffectedFileRequestAndCheckResult(session: server.Session, request: server.protocol.Request, expectedFileList: { projectFileName: string, files: FileOrFolder[] }[]) {
             const response: server.protocol.CompileOnSaveAffectedFileListSingleProject[] = session.executeCommand(request).response;
@@ -105,7 +109,7 @@ namespace ts.projectSystem {
 
             it("should contains only itself if a module file's shape didn't change, and all files referencing it if its shape changed", () => {
                 const host = createServerHost([moduleFile1, file1Consumer1, file1Consumer2, globalFile3, moduleFile2, configFile, libFile]);
-                const typingsInstaller = new TestTypingsInstaller("/a/data/", host);
+                const typingsInstaller = createTestTypingsInstaller(host);
                 const session = new server.Session(host, nullCancellationToken, /*useSingleInferredProject*/ false, typingsInstaller, Utils.byteLength, process.hrtime, nullLogger, /*canUseEvents*/ false);
 
                 openFilesForSession([moduleFile1, file1Consumer1], session);
@@ -130,7 +134,7 @@ namespace ts.projectSystem {
 
             it("should be up-to-date with the reference map changes", () => {
                 const host = createServerHost([moduleFile1, file1Consumer1, file1Consumer2, globalFile3, moduleFile2, configFile, libFile]);
-                const typingsInstaller = new TestTypingsInstaller("/a/data/", host);
+                const typingsInstaller = createTestTypingsInstaller(host);
                 const session = new server.Session(host, nullCancellationToken, /*useSingleInferredProject*/ false, typingsInstaller, Utils.byteLength, process.hrtime, nullLogger, /*canUseEvents*/ false);
 
                 openFilesForSession([moduleFile1, file1Consumer1], session);
@@ -177,7 +181,7 @@ namespace ts.projectSystem {
 
             it("should be up-to-date with changes made in non-open files", () => {
                 const host = createServerHost([moduleFile1, file1Consumer1, file1Consumer2, globalFile3, moduleFile2, configFile, libFile]);
-                const typingsInstaller = new TestTypingsInstaller("/a/data/", host);
+                const typingsInstaller = createTestTypingsInstaller(host);
                 const session = new server.Session(host, nullCancellationToken, /*useSingleInferredProject*/ false, typingsInstaller, Utils.byteLength, process.hrtime, nullLogger, /*canUseEvents*/ false);
 
                 openFilesForSession([moduleFile1], session);
@@ -195,7 +199,7 @@ namespace ts.projectSystem {
 
             it("should be up-to-date with deleted files", () => {
                 const host = createServerHost([moduleFile1, file1Consumer1, file1Consumer2, globalFile3, moduleFile2, configFile, libFile]);
-                const typingsInstaller = new TestTypingsInstaller("/a/data/", host);
+                const typingsInstaller = createTestTypingsInstaller(host);
                 const session = new server.Session(host, nullCancellationToken, /*useSingleInferredProject*/ false, typingsInstaller, Utils.byteLength, process.hrtime, nullLogger, /*canUseEvents*/ false);
 
                 openFilesForSession([moduleFile1], session);
@@ -210,7 +214,7 @@ namespace ts.projectSystem {
 
             it("should be up-to-date with newly created files", () => {
                 const host = createServerHost([moduleFile1, file1Consumer1, file1Consumer2, globalFile3, moduleFile2, configFile, libFile]);
-                const typingsInstaller = new TestTypingsInstaller("/a/data/", host);
+                const typingsInstaller = createTestTypingsInstaller(host);
                 const session = new server.Session(host, nullCancellationToken, /*useSingleInferredProject*/ false, typingsInstaller, Utils.byteLength, process.hrtime, nullLogger, /*canUseEvents*/ false);
 
                 openFilesForSession([moduleFile1], session);
@@ -247,7 +251,7 @@ namespace ts.projectSystem {
                 };
 
                 const host = createServerHost([moduleFile1, file1Consumer1, configFile, libFile]);
-                const typingsInstaller = new TestTypingsInstaller("/a/data/", host);
+                const typingsInstaller = createTestTypingsInstaller(host);
                 const session = new server.Session(host, nullCancellationToken, /*useSingleInferredProject*/ false, typingsInstaller, Utils.byteLength, process.hrtime, nullLogger, /*canUseEvents*/ false);
 
                 openFilesForSession([moduleFile1, file1Consumer1], session);
@@ -264,7 +268,7 @@ namespace ts.projectSystem {
 
             it("should return all files if a global file changed shape", () => {
                 const host = createServerHost([moduleFile1, file1Consumer1, file1Consumer2, globalFile3, moduleFile2, configFile, libFile]);
-                const typingsInstaller = new TestTypingsInstaller("/a/data/", host);
+                const typingsInstaller = createTestTypingsInstaller(host);
                 const session = new server.Session(host, nullCancellationToken, /*useSingleInferredProject*/ false, typingsInstaller, Utils.byteLength, process.hrtime, nullLogger, /*canUseEvents*/ false);
 
                 openFilesForSession([globalFile3], session);
@@ -290,7 +294,7 @@ namespace ts.projectSystem {
                 };
 
                 const host = createServerHost([moduleFile1, file1Consumer1, file1Consumer2, configFile, libFile]);
-                const typingsInstaller = new TestTypingsInstaller("/a/data/", host);
+                const typingsInstaller = createTestTypingsInstaller(host);
                 const session = new server.Session(host, nullCancellationToken, /*useSingleInferredProject*/ false, typingsInstaller, Utils.byteLength, process.hrtime, nullLogger, /*canUseEvents*/ false);
                 openFilesForSession([moduleFile1], session);
                 sendAffectedFileRequestAndCheckResult(session, moduleFile1FileListRequest, []);
@@ -308,7 +312,7 @@ namespace ts.projectSystem {
                 };
 
                 const host = createServerHost([moduleFile1, file1Consumer1, configFile, libFile]);
-                const typingsInstaller = new TestTypingsInstaller("/a/data/", host);
+                const typingsInstaller = createTestTypingsInstaller(host);
                 const session = new server.Session(host, nullCancellationToken, /*useSingleInferredProject*/ false, typingsInstaller, Utils.byteLength, process.hrtime, nullLogger, /*canUseEvents*/ false);
                 openFilesForSession([moduleFile1], session);
 
@@ -337,7 +341,7 @@ namespace ts.projectSystem {
                 };
 
                 const host = createServerHost([moduleFile1, file1Consumer1, configFile, libFile]);
-                const typingsInstaller = new TestTypingsInstaller("/a/data/", host);
+                const typingsInstaller = createTestTypingsInstaller(host);
                 const session = new server.Session(host, nullCancellationToken, /*useSingleInferredProject*/ false, typingsInstaller, Utils.byteLength, process.hrtime, nullLogger, /*canUseEvents*/ false);
                 openFilesForSession([moduleFile1], session);
 
@@ -359,7 +363,7 @@ namespace ts.projectSystem {
                     content: `import {y} from "./file1Consumer1";`
                 };
                 const host = createServerHost([moduleFile1, file1Consumer1, file1Consumer1Consumer1, globalFile3, configFile, libFile]);
-                const typingsInstaller = new TestTypingsInstaller("/a/data/", host);
+                const typingsInstaller = createTestTypingsInstaller(host);
                 const session = new server.Session(host, nullCancellationToken, /*useSingleInferredProject*/ false, typingsInstaller, Utils.byteLength, process.hrtime, nullLogger, /*canUseEvents*/ false);
 
                 openFilesForSession([moduleFile1, file1Consumer1], session);
@@ -392,7 +396,7 @@ namespace ts.projectSystem {
                     export var t2 = 10;`
                 };
                 const host = createServerHost([file1, file2, configFile]);
-                const typingsInstaller = new TestTypingsInstaller("/a/data/", host);
+                const typingsInstaller = createTestTypingsInstaller(host);
                 const session = new server.Session(host, nullCancellationToken, /*useSingleInferredProject*/ false, typingsInstaller, Utils.byteLength, process.hrtime, nullLogger, /*canUseEvents*/ false);
 
                 openFilesForSession([file1, file2], session);
@@ -475,7 +479,7 @@ namespace ts.projectSystem {
                 content: `{}`
             };
             const host = createServerHost([file1, file2, configFile, libFile]);
-            const typingsInstaller = new TestTypingsInstaller("/a/data/", host);
+            const typingsInstaller = createTestTypingsInstaller(host);
             const session = new server.Session(host, nullCancellationToken, /*useSingleInferredProject*/ false, typingsInstaller, Utils.byteLength, process.hrtime, nullLogger, /*canUseEvents*/ false);
 
             openFilesForSession([file1, file2], session);
diff --git a/src/harness/unittests/tsserverProjectSystem.ts b/src/harness/unittests/tsserverProjectSystem.ts
index 4575ce06b4..f34dfa31fc 100644
--- a/src/harness/unittests/tsserverProjectSystem.ts
+++ b/src/harness/unittests/tsserverProjectSystem.ts
@@ -2,6 +2,8 @@
 /// <reference path="../../server/typingsInstaller/typingsInstaller.ts" />
 
 namespace ts.projectSystem {
+    import TI = server.typingsInstaller;
+
     const safeList = {
         path: <Path>"/safeList.json",
         content: JSON.stringify({
@@ -13,6 +15,14 @@ namespace ts.projectSystem {
         })
     };
 
+    export interface PostExecAction {
+        readonly requestKind: TI.RequestKind;
+        readonly error: Error;
+        readonly stdout: string;
+        readonly stderr: string;
+        readonly callback: (err: Error, stdout: string, stderr: string) => void;
+    }
+
     export function notImplemented(): any {
         throw new Error("Not yet implemented");
     }
@@ -39,21 +49,27 @@ namespace ts.projectSystem {
         content: libFileContent
     };
 
-    export class TestTypingsInstaller extends server.typingsInstaller.TypingsInstaller implements server.ITypingsInstaller {
+    export class TestTypingsInstaller extends TI.TypingsInstaller implements server.ITypingsInstaller {
         protected projectService: server.ProjectService;
-        constructor(readonly globalTypingsCacheLocation: string, readonly installTypingHost: server.ServerHost) {
-            super(globalTypingsCacheLocation, safeList.path);
+        constructor(readonly globalTypingsCacheLocation: string, throttleLimit: number, readonly installTypingHost: server.ServerHost) {
+            super(globalTypingsCacheLocation, "npm", safeList.path, throttleLimit);
             this.init();
         }
 
         safeFileList = safeList.path;
-        postInstallActions: ((map: (t: string[]) => string[]) => void)[] = [];
+        protected postExecActions: PostExecAction[] = [];
 
-        runPostInstallActions(map: (t: string[]) => string[]) {
-            for (const f of this.postInstallActions) {
-                f(map);
+        executePendingCommands() {
+            const actionsToRun = this.postExecActions;
+            this.postExecActions = [];
+            for (const action of actionsToRun) {
+                action.callback(action.error, action.stdout, action.stderr);
             }
-            this.postInstallActions = [];
+        }
+
+        checkPendingCommands(expected: TI.RequestKind[]) {
+            assert.equal(this.postExecActions.length, expected.length, `Expected ${expected.length} post install actions`);
+            this.postExecActions.forEach((act, i) => assert.equal(act.requestKind, expected[i], "Unexpected post install action"));
         }
 
         onProjectClosed(p: server.Project) {
@@ -67,14 +83,15 @@ namespace ts.projectSystem {
             return this.installTypingHost;
         }
 
-        isPackageInstalled(packageName: string) {
-            return true;
-        }
-
-        runInstall(cachePath: string, typingsToInstall: string[], postInstallAction: (installedTypings: string[]) => void) {
-            this.postInstallActions.push(map => {
-                postInstallAction(map(typingsToInstall));
-            });
+        runCommand(requestKind: TI.RequestKind, requestId: number, command: string, cwd: string, cb: (err: Error, stdout: string, stderr: string) => void): void {
+            switch (requestKind) {
+                case TI.NpmViewRequest:
+                case TI.NpmInstallRequest:
+                    break;
+                default:
+                    assert.isTrue(false, `request ${requestKind} is not supported`);
+            }
+            this.addPostExecAction(requestKind, "success", cb);
         }
 
         sendResponse(response: server.SetTypings | server.InvalidateCachedTypings) {
@@ -85,6 +102,26 @@ namespace ts.projectSystem {
             const request = server.createInstallTypingsRequest(project, typingOptions, this.globalTypingsCacheLocation);
             this.install(request);
         }
+
+        addPostExecAction(requestKind: TI.RequestKind, stdout: string | string[], cb: TI.RequestCompletedAction) {
+            const out = typeof stdout === "string" ? stdout : createNpmPackageJsonString(stdout);
+            const action: PostExecAction = {
+                error: undefined,
+                stdout: out,
+                stderr: "",
+                callback: cb,
+                requestKind
+            };
+            this.postExecActions.push(action);
+        }
+    }
+
+    function createNpmPackageJsonString(installedTypings: string[]): string {
+        const dependencies: MapLike<any> = {};
+        for (const typing of installedTypings) {
+            dependencies[typing] = "1.0.0";
+        }
+        return JSON.stringify({ dependencies: dependencies });
     }
 
     export function getExecutingFilePathFromLibFile(libFilePath: string): string {
@@ -124,7 +161,7 @@ namespace ts.projectSystem {
 
     export function createSession(host: server.ServerHost, typingsInstaller?: server.ITypingsInstaller) {
         if (typingsInstaller === undefined) {
-            typingsInstaller = new TestTypingsInstaller("/a/data/", host);
+            typingsInstaller = new TestTypingsInstaller("/a/data/", /*throttleLimit*/5, host);
         }
         return new server.Session(host, nullCancellationToken, /*useSingleInferredProject*/ false, typingsInstaller, Utils.byteLength, process.hrtime, nullLogger, /*canUseEvents*/ false);
     }
@@ -1615,7 +1652,7 @@ namespace ts.projectSystem {
             const host: TestServerHost & ModuleResolutionHost = createServerHost([file1, lib]);
             const resolutionTrace: string[] = [];
             host.trace = resolutionTrace.push.bind(resolutionTrace);
-            const projectService = createProjectService(host, { typingsInstaller: new TestTypingsInstaller("/a/cache", host) });
+            const projectService = createProjectService(host, { typingsInstaller: new TestTypingsInstaller("/a/cache", /*throttleLimit*/5, host) });
 
             projectService.setCompilerOptionsForInferredProjects({ traceResolution: true, allowJs: true });
             projectService.openClientFile(file1.path);
diff --git a/src/harness/unittests/typingsInstaller.ts b/src/harness/unittests/typingsInstaller.ts
index 47373bfd26..9dd1247c89 100644
--- a/src/harness/unittests/typingsInstaller.ts
+++ b/src/harness/unittests/typingsInstaller.ts
@@ -1,9 +1,50 @@
-/// <reference path="../harness.ts" />
+/// <reference path="../harness.ts" />
 /// <reference path="./tsserverProjectSystem.ts" />
 /// <reference path="../../server/typingsInstaller/typingsInstaller.ts" />
 
 namespace ts.projectSystem {
-    describe("typings installer", () => {
+    import TI = server.typingsInstaller;
+
+    interface InstallerParams {
+        globalTypingsCacheLocation?: string;
+        throttleLimit?: number;
+    }
+
+    class Installer extends TestTypingsInstaller {
+        constructor(host: server.ServerHost, p?: InstallerParams) {
+            super(
+                (p && p.globalTypingsCacheLocation) || "/a/data",
+                (p && p.throttleLimit) || 5,
+                host);
+        }
+
+        installAll(expectedView: typeof TI.NpmViewRequest[], expectedInstall: typeof TI.NpmInstallRequest[]) {
+            this.checkPendingCommands(expectedView);
+            this.executePendingCommands();
+            this.checkPendingCommands(expectedInstall);
+            this.executePendingCommands();
+        }
+    }
+
+    describe("typingsInstaller", () => {
+        function executeCommand(self: Installer, host: TestServerHost, installedTypings: string[], typingFiles: FileOrFolder[], requestKind: TI.RequestKind, cb: TI.RequestCompletedAction): void {
+            switch (requestKind) {
+                case TI.NpmInstallRequest:
+                    self.addPostExecAction(requestKind, installedTypings, (err, stdout, stderr) => {
+                        for (const file of typingFiles) {
+                            host.createFileOrFolder(file, /*createParentDirectory*/ true);
+                        }
+                        cb(err, stdout, stderr);
+                    });
+                    break;
+                case TI.NpmViewRequest:
+                    self.addPostExecAction(requestKind, installedTypings, cb);
+                    break;
+                default:
+                    assert.isTrue(false, `unexpected request kind ${requestKind}`);
+                    break;
+            }
+        }
         it("configured projects (typings installed) 1", () => {
             const file1 = {
                 path: "/a/b/app.js",
@@ -34,9 +75,18 @@ namespace ts.projectSystem {
                 path: "/a/data/node_modules/@types/jquery/index.d.ts",
                 content: "declare const $: { x: number }"
             };
-
             const host = createServerHost([file1, tsconfig, packageJson]);
-            const installer = new TestTypingsInstaller("/a/data/", host);
+            const installer = new (class extends Installer {
+                constructor() {
+                    super(host);
+                }
+                runCommand(requestKind: TI.RequestKind, requestId: number, command: string, cwd: string, cb: server.typingsInstaller.RequestCompletedAction) {
+                    const installedTypings = ["@types/jquery"];
+                    const typingFiles = [jquery];
+                    executeCommand(this, host, installedTypings, typingFiles, requestKind, cb);
+                }
+            })();
+
             const projectService = createProjectService(host, { useSingleInferredProject: true, typingsInstaller: installer });
             projectService.openClientFile(file1.path);
 
@@ -44,13 +94,8 @@ namespace ts.projectSystem {
             const p = projectService.configuredProjects[0];
             checkProjectActualFiles(p, [file1.path]);
 
-            assert(host.fileExists(combinePaths(installer.globalTypingsCacheLocation, "package.json")));
+            installer.installAll([TI.NpmViewRequest], [TI.NpmInstallRequest]);
 
-            installer.runPostInstallActions(t => {
-                assert.deepEqual(t, ["jquery"]);
-                host.createFileOrFolder(jquery, /*createParentDirectory*/ true);
-                return ["@types/jquery"];
-            });
             checkNumberOfProjects(projectService, { configuredProjects: 1 });
             checkProjectActualFiles(p, [file1.path, jquery.path]);
         });
@@ -75,7 +120,16 @@ namespace ts.projectSystem {
                 content: "declare const $: { x: number }"
             };
             const host = createServerHost([file1, packageJson]);
-            const installer = new TestTypingsInstaller("/a/data/", host);
+            const installer = new (class extends Installer {
+                constructor() {
+                    super(host);
+                }
+                runCommand(requestKind: TI.RequestKind, requestId: number, command: string, cwd: string, cb: server.typingsInstaller.RequestCompletedAction) {
+                    const installedTypings = ["@types/jquery"];
+                    const typingFiles = [jquery];
+                    executeCommand(this, host, installedTypings, typingFiles, requestKind, cb);
+                }
+            })();
 
             const projectService = createProjectService(host, { useSingleInferredProject: true, typingsInstaller: installer });
             projectService.openClientFile(file1.path);
@@ -84,13 +138,8 @@ namespace ts.projectSystem {
             const p = projectService.inferredProjects[0];
             checkProjectActualFiles(p, [file1.path]);
 
-            assert(host.fileExists(combinePaths(installer.globalTypingsCacheLocation, "package.json")));
+            installer.installAll([TI.NpmViewRequest], [TI.NpmInstallRequest]);
 
-            installer.runPostInstallActions(t => {
-                assert.deepEqual(t, ["jquery"]);
-                host.createFileOrFolder(jquery, /*createParentDirectory*/ true);
-                return ["@types/jquery"];
-            });
             checkNumberOfProjects(projectService, { inferredProjects: 1 });
             checkProjectActualFiles(p, [file1.path, jquery.path]);
         });
@@ -101,9 +150,9 @@ namespace ts.projectSystem {
                 content: ""
             };
             const host = createServerHost([file1]);
-            const installer = new (class extends TestTypingsInstaller {
+            const installer = new (class extends Installer {
                 constructor() {
-                    super("", host);
+                    super(host);
                 }
                 enqueueInstallTypingsRequest() {
                     assert(false, "auto discovery should not be enabled");
@@ -117,6 +166,7 @@ namespace ts.projectSystem {
                 options: {},
                 rootFiles: [toExternalFile(file1.path)]
             });
+            installer.checkPendingCommands([]);
             // by default auto discovery will kick in if project contain only .js/.d.ts files
             // in this case project contain only ts files - no auto discovery
             projectService.checkNumberOfProjects({ externalProjects: 1 });
@@ -128,9 +178,9 @@ namespace ts.projectSystem {
                 content: ""
             };
             const host = createServerHost([file1]);
-            const installer = new (class extends TestTypingsInstaller {
+            const installer = new (class extends Installer {
                 constructor() {
-                    super("", host);
+                    super(host);
                 }
                 enqueueInstallTypingsRequest() {
                     assert(false, "auto discovery should not be enabled");
@@ -145,6 +195,7 @@ namespace ts.projectSystem {
                 rootFiles: [toExternalFile(file1.path)],
                 typingOptions: { include: ["jquery"] }
             });
+            installer.checkPendingCommands([]);
             // by default auto discovery will kick in if project contain only .js/.d.ts files
             // in this case project contain only ts files - no auto discovery even if typing options is set
             projectService.checkNumberOfProjects({ externalProjects: 1 });
@@ -155,21 +206,24 @@ namespace ts.projectSystem {
                 path: "/a/b/app.ts",
                 content: ""
             };
+            const jquery = {
+                path: "/a/data/node_modules/@types/jquery/index.d.ts",
+                content: "declare const $: { x: number }"
+            };
             const host = createServerHost([file1]);
             let enqueueIsCalled = false;
-            let runInstallIsCalled = false;
-            const installer = new (class extends TestTypingsInstaller {
+            const installer = new (class extends Installer {
                 constructor() {
-                    super("", host);
+                    super(host);
                 }
                 enqueueInstallTypingsRequest(project: server.Project, typingOptions: TypingOptions) {
                     enqueueIsCalled = true;
                     super.enqueueInstallTypingsRequest(project, typingOptions);
                 }
-                runInstall(cachePath: string, typingsToInstall: string[], postInstallAction: (installedTypings: string[]) => void): void {
-                    assert.deepEqual(typingsToInstall, ["node"]);
-                    runInstallIsCalled = true;
-                    super.runInstall(cachePath, typingsToInstall, postInstallAction);
+                runCommand(requestKind: TI.RequestKind, requestId: number, command: string, cwd: string, cb: TI.RequestCompletedAction): void {
+                    const installedTypings = ["@types/jquery"];
+                    const typingFiles = [jquery];
+                    executeCommand(this, host, installedTypings, typingFiles, requestKind, cb);
                 }
             })();
 
@@ -181,10 +235,12 @@ namespace ts.projectSystem {
                 rootFiles: [toExternalFile(file1.path)],
                 typingOptions: { enableAutoDiscovery: true, include: ["node"] }
             });
+
+            assert.isTrue(enqueueIsCalled, "expected enqueueIsCalled to be true");
+            installer.installAll([TI.NpmViewRequest], [TI.NpmInstallRequest]);
+
             // autoDiscovery is set in typing options - use it even if project contains only .ts files
             projectService.checkNumberOfProjects({ externalProjects: 1 });
-            assert.isTrue(enqueueIsCalled, "expected 'enqueueIsCalled' to be true");
-            assert.isTrue(runInstallIsCalled, "expected 'runInstallIsCalled' to be true");
         });
 
         it("external project - no typing options, with only js, jsx, d.ts files", () => {
@@ -214,7 +270,16 @@ namespace ts.projectSystem {
             };
 
             const host = createServerHost([file1, file2, file3]);
-            const installer = new TestTypingsInstaller("/a/data/", host);
+            const installer = new (class extends Installer {
+                constructor() {
+                    super(host);
+                }
+                runCommand(requestKind: TI.RequestKind, requestId: number, command: string, cwd: string, cb: TI.RequestCompletedAction): void {
+                    const installedTypings = ["@types/lodash", "@types/react"];
+                    const typingFiles = [lodash, react];
+                    executeCommand(this, host, installedTypings, typingFiles, requestKind, cb);
+                }
+            })();
 
             const projectFileName = "/a/app/test.csproj";
             const projectService = createProjectService(host, { typingsInstaller: installer });
@@ -229,12 +294,7 @@ namespace ts.projectSystem {
             projectService.checkNumberOfProjects({ externalProjects: 1 });
             checkProjectActualFiles(p, [file1.path, file2.path, file3.path]);
 
-            installer.runPostInstallActions(t => {
-                assert.deepEqual(t, ["lodash", "react"]);
-                host.createFileOrFolder(lodash, /*createParentDirectory*/ true);
-                host.createFileOrFolder(react, /*createParentDirectory*/ true);
-                return ["@types/lodash", "@types/react"];
-            });
+            installer.installAll([TI.NpmViewRequest, TI.NpmViewRequest], [TI.NpmInstallRequest], );
 
             checkNumberOfProjects(projectService, { externalProjects: 1 });
             checkProjectActualFiles(p, [file1.path, file2.path, file3.path, lodash.path, react.path]);
@@ -254,19 +314,18 @@ namespace ts.projectSystem {
 
             const host = createServerHost([file1, file2]);
             let enqueueIsCalled = false;
-            let runInstallIsCalled = false;
-            let runPostInstallIsCalled = false;
-            const installer = new (class extends TestTypingsInstaller {
+            const installer = new (class extends Installer {
                 constructor() {
-                    super("/a/data/", host);
+                    super(host);
                 }
                 enqueueInstallTypingsRequest(project: server.Project, typingOptions: TypingOptions) {
                     enqueueIsCalled = true;
                     super.enqueueInstallTypingsRequest(project, typingOptions);
                 }
-                runInstall(cachePath: string, typingsToInstall: string[], postInstallAction: (installedTypings: string[]) => void): void {
-                    runInstallIsCalled = true;
-                    super.runInstall(cachePath, typingsToInstall, postInstallAction);
+                runCommand(requestKind: TI.RequestKind, requestId: number, command: string, cwd: string, cb: TI.RequestCompletedAction): void {
+                    const installedTypings: string[] = [];
+                    const typingFiles: FileOrFolder[] = [];
+                    executeCommand(this, host, installedTypings, typingFiles, requestKind, cb);
                 }
             })();
 
@@ -283,16 +342,10 @@ namespace ts.projectSystem {
             projectService.checkNumberOfProjects({ externalProjects: 1 });
             checkProjectActualFiles(p, [file1.path, file2.path]);
 
-            installer.runPostInstallActions(t => {
-                runPostInstallIsCalled = true;
-                return [];
-            });
+            installer.checkPendingCommands([]);
 
             checkNumberOfProjects(projectService, { externalProjects: 1 });
             checkProjectActualFiles(p, [file1.path, file2.path]);
-            assert.isFalse(enqueueIsCalled, "expected 'enqueueIsCalled' to be false");
-            assert.isFalse(runInstallIsCalled, "expected 'runInstallIsCalled' to be false");
-            assert.isFalse(runPostInstallIsCalled, "expected 'runPostInstallIsCalled' to be false");
         });
 
         it("external project - with typing options, with only js, d.ts files", () => {
@@ -340,7 +393,16 @@ namespace ts.projectSystem {
             };
 
             const host = createServerHost([file1, file2, file3, packageJson]);
-            const installer = new TestTypingsInstaller("/a/data/", host);
+            const installer = new (class extends Installer {
+                constructor() {
+                    super(host);
+                }
+                runCommand(requestKind: TI.RequestKind, requestId: number, command: string, cwd: string, cb: TI.RequestCompletedAction): void {
+                    const installedTypings = ["@types/commander", "@types/express", "@types/jquery", "@types/moment"];
+                    const typingFiles = [commander, express, jquery, moment];
+                    executeCommand(this, host, installedTypings, typingFiles, requestKind, cb);
+                }
+            })();
 
             const projectFileName = "/a/app/test.csproj";
             const projectService = createProjectService(host, { typingsInstaller: installer });
@@ -355,17 +417,215 @@ namespace ts.projectSystem {
             projectService.checkNumberOfProjects({ externalProjects: 1 });
             checkProjectActualFiles(p, [file1.path, file2.path, file3.path]);
 
-            installer.runPostInstallActions(t => {
-                assert.deepEqual(t, ["jquery", "moment", "express", "commander" ]);
-                host.createFileOrFolder(commander, /*createParentDirectory*/ true);
-                host.createFileOrFolder(express, /*createParentDirectory*/ true);
-                host.createFileOrFolder(jquery, /*createParentDirectory*/ true);
-                host.createFileOrFolder(moment, /*createParentDirectory*/ true);
-                return ["@types/commander", "@types/express", "@types/jquery", "@types/moment"];
-            });
+            installer.installAll(
+                [TI.NpmViewRequest, TI.NpmViewRequest, TI.NpmViewRequest, TI.NpmViewRequest],
+                [TI.NpmInstallRequest]
+            );
 
             checkNumberOfProjects(projectService, { externalProjects: 1 });
             checkProjectActualFiles(p, [file1.path, file2.path, file3.path, commander.path, express.path, jquery.path, moment.path]);
         });
+
+        it("Throttle - delayed typings to install", () => {
+            const lodashJs = {
+                path: "/a/b/lodash.js",
+                content: ""
+            };
+            const commanderJs = {
+                path: "/a/b/commander.js",
+                content: ""
+            };
+            const file3 = {
+                path: "/a/b/file3.d.ts",
+                content: ""
+            };
+            const packageJson = {
+                path: "/a/b/package.json",
+                content: JSON.stringify({
+                    name: "test",
+                    dependencies: {
+                        express: "^3.1.0"
+                    }
+                })
+            };
+
+            const commander = {
+                path: "/a/data/node_modules/@types/commander/index.d.ts",
+                content: "declare const commander: { x: number }"
+            };
+            const express = {
+                path: "/a/data/node_modules/@types/express/index.d.ts",
+                content: "declare const express: { x: number }"
+            };
+            const jquery = {
+                path: "/a/data/node_modules/@types/jquery/index.d.ts",
+                content: "declare const jquery: { x: number }"
+            };
+            const moment = {
+                path: "/a/data/node_modules/@types/moment/index.d.ts",
+                content: "declare const moment: { x: number }"
+            };
+            const lodash = {
+                path: "/a/data/node_modules/@types/lodash/index.d.ts",
+                content: "declare const lodash: { x: number }"
+            };
+
+            const typingFiles = [commander, express, jquery, moment, lodash];
+            const host = createServerHost([lodashJs, commanderJs, file3, packageJson]);
+            const installer = new (class extends Installer {
+                constructor() {
+                    super(host, { throttleLimit: 3 });
+                }
+                runCommand(requestKind: TI.RequestKind, requestId: number, command: string, cwd: string, cb: TI.RequestCompletedAction): void {
+                    const installedTypings = ["@types/commander", "@types/express", "@types/jquery", "@types/moment", "@types/lodash"];
+                    executeCommand(this, host, installedTypings, typingFiles, requestKind, cb);
+                }
+            })();
+
+            const projectFileName = "/a/app/test.csproj";
+            const projectService = createProjectService(host, { typingsInstaller: installer });
+            projectService.openExternalProject({
+                projectFileName,
+                options: { allowJS: true, moduleResolution: ModuleResolutionKind.NodeJs },
+                rootFiles: [toExternalFile(lodashJs.path), toExternalFile(commanderJs.path), toExternalFile(file3.path)],
+                typingOptions: { include: ["jquery", "moment"] }
+            });
+
+            const p = projectService.externalProjects[0];
+            projectService.checkNumberOfProjects({ externalProjects: 1 });
+            checkProjectActualFiles(p, [lodashJs.path, commanderJs.path, file3.path]);
+            // expected 3 view requests in the queue
+            installer.checkPendingCommands([TI.NpmViewRequest, TI.NpmViewRequest, TI.NpmViewRequest]);
+            assert.equal(installer.pendingRunRequests.length, 2, "expected 2 pending requests");
+
+            // push view requests
+            installer.executePendingCommands();
+            // expected 2 remaining view requests in the queue
+            installer.checkPendingCommands([TI.NpmViewRequest, TI.NpmViewRequest]);
+            // push view requests
+            installer.executePendingCommands();
+            // expected one install request
+            installer.checkPendingCommands([TI.NpmInstallRequest]);
+            installer.executePendingCommands();
+            // expected all typings file to exist
+            for (const f of typingFiles) {
+                assert.isTrue(host.fileExists(f.path), `expected file ${f.path} to exist`);
+            }
+
+            checkNumberOfProjects(projectService, { externalProjects: 1 });
+            checkProjectActualFiles(p, [lodashJs.path, commanderJs.path, file3.path, commander.path, express.path, jquery.path, moment.path, lodash.path]);
+        });
+
+        it("Throttle - delayed run install requests", () => {
+            const lodashJs = {
+                path: "/a/b/lodash.js",
+                content: ""
+            };
+            const commanderJs = {
+                path: "/a/b/commander.js",
+                content: ""
+            };
+            const file3 = {
+                path: "/a/b/file3.d.ts",
+                content: ""
+            };
+
+            const commander = {
+                path: "/a/data/node_modules/@types/commander/index.d.ts",
+                content: "declare const commander: { x: number }",
+                typings: "@types/commander"
+            };
+            const jquery = {
+                path: "/a/data/node_modules/@types/jquery/index.d.ts",
+                content: "declare const jquery: { x: number }",
+                typings: "@types/jquery"
+            };
+            const lodash = {
+                path: "/a/data/node_modules/@types/lodash/index.d.ts",
+                content: "declare const lodash: { x: number }",
+                typings: "@types/lodash"
+            };
+            const cordova = {
+                path: "/a/data/node_modules/@types/cordova/index.d.ts",
+                content: "declare const cordova: { x: number }",
+                typings: "@types/cordova"
+            };
+            const grunt = {
+                path: "/a/data/node_modules/@types/grunt/index.d.ts",
+                content: "declare const grunt: { x: number }",
+                typings: "@types/grunt"
+            };
+            const gulp = {
+                path: "/a/data/node_modules/@types/gulp/index.d.ts",
+                content: "declare const gulp: { x: number }",
+                typings: "@types/gulp"
+            };
+
+            const host = createServerHost([lodashJs, commanderJs, file3]);
+            const installer = new (class extends Installer {
+                constructor() {
+                    super(host, { throttleLimit: 3 });
+                }
+                runCommand(requestKind: TI.RequestKind, requestId: number, command: string, cwd: string, cb: TI.RequestCompletedAction): void {
+                    if (requestKind === TI.NpmInstallRequest) {
+                        let typingFiles: (FileOrFolder & { typings: string}) [] = [];
+                        if (command.indexOf("commander") >= 0) {
+                            typingFiles = [commander, jquery, lodash, cordova];
+                        }
+                        else {
+                            typingFiles = [grunt, gulp];
+                        }
+                        executeCommand(this, host, typingFiles.map(f => f.typings), typingFiles, requestKind, cb);
+                    }
+                    else {
+                        executeCommand(this, host, [], [], requestKind, cb);
+                    }
+                }
+            })();
+
+            // Create project #1 with 4 typings
+            const projectService = createProjectService(host, { typingsInstaller: installer });
+            const projectFileName1 = "/a/app/test1.csproj";
+            projectService.openExternalProject({
+                projectFileName: projectFileName1,
+                options: { allowJS: true, moduleResolution: ModuleResolutionKind.NodeJs },
+                rootFiles: [toExternalFile(lodashJs.path), toExternalFile(commanderJs.path), toExternalFile(file3.path)],
+                typingOptions: { include: ["jquery", "cordova" ] }
+            });
+
+            installer.checkPendingCommands([TI.NpmViewRequest, TI.NpmViewRequest, TI.NpmViewRequest]);
+            assert.equal(installer.pendingRunRequests.length, 1, "expect one throttled request");
+
+            // Create project #2 with 2 typings
+            const projectFileName2 = "/a/app/test2.csproj";
+            projectService.openExternalProject({
+                projectFileName: projectFileName2,
+                options: { allowJS: true, moduleResolution: ModuleResolutionKind.NodeJs },
+                rootFiles: [toExternalFile(file3.path)],
+                typingOptions: { include: ["grunt", "gulp"] }
+            });
+            assert.equal(installer.pendingRunRequests.length, 3, "expect three throttled request");
+
+            const p1 = projectService.externalProjects[0];
+            const p2 = projectService.externalProjects[1];
+            projectService.checkNumberOfProjects({ externalProjects: 2 });
+            checkProjectActualFiles(p1, [lodashJs.path, commanderJs.path, file3.path]);
+            checkProjectActualFiles(p2, [file3.path]);
+
+
+            installer.executePendingCommands();
+            // expected one view request from the first project and two - from the second one
+            installer.checkPendingCommands([TI.NpmViewRequest, TI.NpmViewRequest, TI.NpmViewRequest]);
+            assert.equal(installer.pendingRunRequests.length, 0, "expected no throttled requests");
+
+            installer.executePendingCommands();
+
+            // should be two install requests from both projects
+            installer.checkPendingCommands([TI.NpmInstallRequest, TI.NpmInstallRequest]);
+            installer.executePendingCommands();
+
+            checkProjectActualFiles(p1, [lodashJs.path, commanderJs.path, file3.path, commander.path, jquery.path, lodash.path, cordova.path]);
+            checkProjectActualFiles(p2, [file3.path, grunt.path, gulp.path ]);
+        });
     });
 }
\ No newline at end of file
diff --git a/src/server/typingsInstaller/nodeTypingsInstaller.ts b/src/server/typingsInstaller/nodeTypingsInstaller.ts
index 0d22b1b364..7df1e9a787 100644
--- a/src/server/typingsInstaller/nodeTypingsInstaller.ts
+++ b/src/server/typingsInstaller/nodeTypingsInstaller.ts
@@ -1,12 +1,16 @@
-/// <reference path="typingsInstaller.ts"/>
+/// <reference path="typingsInstaller.ts"/>
 /// <reference types="node" />
 
 namespace ts.server.typingsInstaller {
-
     const fs: {
         appendFileSync(file: string, content: string): void
     } = require("fs");
 
+    const path: {
+        join(...parts: string[]): string;
+        dirname(path: string): string;
+    } = require("path");
+
     class FileLog implements Log {
         constructor(private readonly logFile?: string) {
         }
@@ -20,37 +24,26 @@ namespace ts.server.typingsInstaller {
     }
 
     export class NodeTypingsInstaller extends TypingsInstaller {
-        private execSync: { (command: string, options: { stdio: "ignore" | "pipe", cwd?: string }): Buffer | string };
-        private exec: { (command: string, options: { cwd: string }, callback?: (error: Error, stdout: string, stderr: string) => void): any };
-        private npmBinPath: string;
+        private readonly exec: { (command: string, options: { cwd: string }, callback?: (error: Error, stdout: string, stderr: string) => void): any };
 
-        private installRunCount = 1;
         readonly installTypingHost: InstallTypingHost = sys;
 
-        constructor(globalTypingsCacheLocation: string, log: Log) {
-            super(globalTypingsCacheLocation, toPath("typingSafeList.json", __dirname, createGetCanonicalFileName(sys.useCaseSensitiveFileNames)), log);
+        constructor(globalTypingsCacheLocation: string, throttleLimit: number, log: Log) {
+            super(
+                globalTypingsCacheLocation,
+                /*npmPath*/ `"${path.join(path.dirname(process.argv[0]), "npm")}"`,
+                toPath("typingSafeList.json", __dirname, createGetCanonicalFileName(sys.useCaseSensitiveFileNames)),
+                throttleLimit,
+                log);
             if (this.log.isEnabled()) {
                 this.log.writeLine(`Process id: ${process.pid}`);
             }
-            const { exec, execSync } = require("child_process");
-            this.execSync = execSync;
+            const { exec } = require("child_process");
             this.exec = exec;
         }
 
         init() {
             super.init();
-            try {
-                this.npmBinPath = this.execSync("npm -g bin", { stdio: "pipe" }).toString().trim();
-                if (this.log.isEnabled()) {
-                    this.log.writeLine(`Global npm bin path '${this.npmBinPath}'`);
-                }
-            }
-            catch (e) {
-                this.npmBinPath = "";
-                if (this.log.isEnabled()) {
-                    this.log.writeLine(`Error when getting npm bin path: ${e}. Set bin path to ""`);
-                }
-            }
             process.on("message", (req: DiscoverTypings | CloseProject) => {
                 switch (req.kind) {
                     case "discover":
@@ -62,23 +55,6 @@ namespace ts.server.typingsInstaller {
             });
         }
 
-        protected isPackageInstalled(packageName: string) {
-            try {
-                const output = this.execSync(`npm list --silent --global --depth=1 ${packageName}`, { stdio: "pipe" }).toString();
-                if (this.log.isEnabled()) {
-                    this.log.writeLine(`IsPackageInstalled::stdout '${output}'`);
-                }
-                return true;
-            }
-            catch (e) {
-                if (this.log.isEnabled()) {
-                    this.log.writeLine(`IsPackageInstalled::err::stdout '${e.stdout && e.stdout.toString()}'`);
-                    this.log.writeLine(`IsPackageInstalled::err::stderr '${e.stdout && e.stderr.toString()}'`);
-                }
-                return false;
-            }
-        }
-
         protected sendResponse(response: SetTypings | InvalidateCachedTypings) {
             if (this.log.isEnabled()) {
                 this.log.writeLine(`Sending response: ${JSON.stringify(response)}`);
@@ -89,61 +65,16 @@ namespace ts.server.typingsInstaller {
             }
         }
 
-        protected runInstall(cachePath: string, typingsToInstall: string[], postInstallAction: (installedTypings: string[]) => void): void {
-            const id = this.installRunCount;
-            this.installRunCount++;
-            let execInstallCmdCount = 0;
-            const filteredTypings: string[] = [];
-            for (const typing of typingsToInstall) {
-                const command = `npm view @types/${typing} --silent name`;
-                this.execAsync("npm view", command, cachePath, id, (err, stdout, stderr) => {
-                    if (stdout) {
-                        filteredTypings.push(typing);
-                    }
-                    execInstallCmdCount++;
-                    if (execInstallCmdCount === typingsToInstall.length) {
-                        installFilteredTypings(this, filteredTypings);
-                    }
-                });
-            }
-
-            function installFilteredTypings(self: NodeTypingsInstaller, filteredTypings: string[]) {
-                const command = `npm install ${filteredTypings.map(t => "@types/" + t).join(" ")} --save-dev`;
-                self.execAsync("npm install", command, cachePath, id, (err, stdout, stderr) => {
-                    if (stdout) {
-                        reportInstalledTypings(self);
-                    }
-                });
-            }
-
-            function reportInstalledTypings(self: NodeTypingsInstaller) {
-                const command = "npm ls -json";
-                self.execAsync("npm ls", command, cachePath, id, (err, stdout, stderr) => {
-                    let installedTypings: string[];
-                    try {
-                        const response = JSON.parse(stdout);
-                        if (response.dependencies) {
-                            installedTypings = getOwnKeys(response.dependencies);
-                        }
-                    }
-                    catch (e) {
-                        self.log.writeLine(`Error parsing installed @types dependencies. Error details: ${e.message}`);
-                    }
-                    postInstallAction(installedTypings || []);
-                });
-            }
-        }
-
-        private execAsync(prefix: string, command: string, cwd: string, requestId: number, cb: (err: Error, stdout: string, stderr: string) => void) {
+        protected runCommand(requestKind: RequestKind, requestId: number, command: string, cwd: string, onRequestCompleted: RequestCompletedAction): void {
             if (this.log.isEnabled()) {
                 this.log.writeLine(`#${requestId} running command '${command}'.`);
             }
             this.exec(command, { cwd }, (err, stdout, stderr) => {
                 if (this.log.isEnabled()) {
-                    this.log.writeLine(`${prefix} #${requestId} stdout: ${stdout}`);
-                    this.log.writeLine(`${prefix} #${requestId} stderr: ${stderr}`);
+                    this.log.writeLine(`${requestKind} #${requestId} stdout: ${stdout}`);
+                    this.log.writeLine(`${requestKind} #${requestId} stderr: ${stderr}`);
                 }
-                cb(err, stdout, stderr);
+                onRequestCompleted(err, stdout, stderr);
             });
         }
     }
@@ -169,6 +100,6 @@ namespace ts.server.typingsInstaller {
         }
         process.exit(0);
     });
-    const installer = new NodeTypingsInstaller(globalTypingsCacheLocation, log);
+    const installer = new NodeTypingsInstaller(globalTypingsCacheLocation, /*throttleLimit*/5, log);
     installer.init();
 }
\ No newline at end of file
diff --git a/src/server/typingsInstaller/typingsInstaller.ts b/src/server/typingsInstaller/typingsInstaller.ts
index e4870a568c..1113e6e270 100644
--- a/src/server/typingsInstaller/typingsInstaller.ts
+++ b/src/server/typingsInstaller/typingsInstaller.ts
@@ -1,4 +1,4 @@
-/// <reference path="../../compiler/core.ts" />
+/// <reference path="../../compiler/core.ts" />
 /// <reference path="../../compiler/moduleNameResolver.ts" />
 /// <reference path="../../services/jsTyping.ts"/>
 /// <reference path="../types.d.ts"/>
@@ -23,15 +23,38 @@ namespace ts.server.typingsInstaller {
         return result.resolvedModule && result.resolvedModule.resolvedFileName;
     }
 
+    export const NpmViewRequest: "npm view" = "npm view";
+    export const NpmInstallRequest: "npm install" = "npm install";
+
+    export type RequestKind = typeof NpmViewRequest | typeof NpmInstallRequest;
+
+    export type RequestCompletedAction = (err: Error, stdout: string, stderr: string) => void;
+    type PendingRequest = {
+        requestKind: RequestKind;
+        requestId: number;
+        command: string;
+        cwd: string;
+        onRequestCompleted: RequestCompletedAction
+    };
+
     export abstract class TypingsInstaller {
-        private packageNameToTypingLocation: Map<string> = createMap<string>();
-        private missingTypingsSet: Map<true> = createMap<true>();
-        private knownCachesSet: Map<true> = createMap<true>();
-        private projectWatchers: Map<FileWatcher[]> = createMap<FileWatcher[]>();
+        private readonly packageNameToTypingLocation: Map<string> = createMap<string>();
+        private readonly missingTypingsSet: Map<true> = createMap<true>();
+        private readonly knownCachesSet: Map<true> = createMap<true>();
+        private readonly projectWatchers: Map<FileWatcher[]> = createMap<FileWatcher[]>();
+        readonly pendingRunRequests: PendingRequest[] = [];
+
+        private installRunCount = 1;
+        private inFlightRequestCount = 0;
 
         abstract readonly installTypingHost: InstallTypingHost;
 
-        constructor(readonly globalCachePath: string, readonly safeListPath: Path, protected readonly log = nullLog) {
+        constructor(
+            readonly globalCachePath: string,
+            readonly npmPath: string,
+            readonly safeListPath: Path,
+            readonly throttleLimit: number,
+            protected readonly log = nullLog) {
             if (this.log.isEnabled()) {
                 this.log.writeLine(`Global cache location '${globalCachePath}', safe file path '${safeListPath}'`);
             }
@@ -224,6 +247,42 @@ namespace ts.server.typingsInstaller {
             });
         }
 
+        private runInstall(cachePath: string, typingsToInstall: string[], postInstallAction: (installedTypings: string[]) => void): void {
+            const requestId = this.installRunCount;
+
+            this.installRunCount++;
+            let execInstallCmdCount = 0;
+            const filteredTypings: string[] = [];
+            for (const typing of typingsToInstall) {
+                execNpmViewTyping(this, typing);
+            }
+
+            function execNpmViewTyping(self: TypingsInstaller, typing: string) {
+                const command = `${self.npmPath} view @types/${typing} --silent name`;
+                self.execAsync(NpmViewRequest, requestId, command, cachePath, (err, stdout, stderr) => {
+                    if (stdout) {
+                        filteredTypings.push(typing);
+                    }
+                    execInstallCmdCount++;
+                    if (execInstallCmdCount === typingsToInstall.length) {
+                        installFilteredTypings(self, filteredTypings);
+                    }
+                });
+            }
+
+            function installFilteredTypings(self: TypingsInstaller, filteredTypings: string[]) {
+                if (filteredTypings.length === 0) {
+                    postInstallAction([]);
+                    return;
+                }
+                const scopedTypings = filteredTypings.map(t => "@types/" + t);
+                const command = `${self.npmPath} install ${scopedTypings.join(" ")} --save-dev`;
+                self.execAsync(NpmInstallRequest, requestId, command, cachePath, (err, stdout, stderr) => {
+                    postInstallAction(stdout ? scopedTypings : []);
+                });
+            }
+        }
+
         private ensureDirectoryExists(directory: string, host: InstallTypingHost): void {
             const directoryName = getDirectoryPath(directory);
             if (!host.directoryExists(directoryName)) {
@@ -267,8 +326,24 @@ namespace ts.server.typingsInstaller {
             };
         }
 
-        protected abstract isPackageInstalled(packageName: string): boolean;
+        private execAsync(requestKind: RequestKind, requestId: number, command: string, cwd: string, onRequestCompleted: RequestCompletedAction): void {
+            this.pendingRunRequests.unshift({ requestKind, requestId, command, cwd, onRequestCompleted });
+            this.executeWithThrottling();
+        }
+
+        private executeWithThrottling() {
+            while (this.inFlightRequestCount < this.throttleLimit && this.pendingRunRequests.length) {
+                this.inFlightRequestCount++;
+                const request = this.pendingRunRequests.pop();
+                this.runCommand(request.requestKind, request.requestId, request.command, request.cwd, (err, stdout, stderr) => {
+                    this.inFlightRequestCount--;
+                    request.onRequestCompleted(err, stdout, stderr);
+                    this.executeWithThrottling();
+                });
+            }
+        }
+
+        protected abstract runCommand(requestKind: RequestKind, requestId: number, command: string, cwd: string, onRequestCompleted: RequestCompletedAction): void;
         protected abstract sendResponse(response: SetTypings | InvalidateCachedTypings): void;
-        protected abstract runInstall(cachePath: string, typingsToInstall: string[], postInstallAction: (installedTypings: string[]) => void): void;
     }
 }
\ No newline at end of file