diff --git a/src/vs/workbench/api/node/extHostDebugService.ts b/src/vs/workbench/api/node/extHostDebugService.ts
index 474c69813d1..f4a7d7eed8f 100644
--- a/src/vs/workbench/api/node/extHostDebugService.ts
+++ b/src/vs/workbench/api/node/extHostDebugService.ts
@@ -340,46 +340,38 @@ export class ExtHostDebugService implements IExtHostDebugService, ExtHostDebugSe
 				});
 			}
 
-			return new Promise(resolve => {
-				if (this._integratedTerminalInstance) {
-					this._integratedTerminalInstance.processId.then(pid => {
-						resolve(hasChildProcesses(pid));
-					}, err => {
-						resolve(true);
-					});
-				} else {
-					resolve(true);
-				}
-			}).then(async needNewTerminal => {
+			let needNewTerminal = true;	// be pessimistic
+			if (this._integratedTerminalInstance) {
+				const pid = await this._integratedTerminalInstance.processId;
+				needNewTerminal = await hasChildProcesses(pid);		// if no processes running in terminal reuse terminal
+			}
 
-				const configProvider = await this._configurationService.getConfigProvider();
-				const shell = this._terminalService.getDefaultShell(true, configProvider);
+			const configProvider = await this._configurationService.getConfigProvider();
+			const shell = this._terminalService.getDefaultShell(true, configProvider);
 
-				if (needNewTerminal || !this._integratedTerminalInstance) {
-					const options: vscode.TerminalOptions = {
-						shellPath: shell,
-						// shellArgs: this._terminalService._getDefaultShellArgs(configProvider),
-						cwd: args.cwd,
-						name: args.title || nls.localize('debug.terminal.title', "debuggee"),
-						env: args.env
-					};
-					delete args.cwd;
-					delete args.env;
-					this._integratedTerminalInstance = this._terminalService.createTerminalFromOptions(options);
-				}
-				const terminal: vscode.Terminal = this._integratedTerminalInstance;
+			if (needNewTerminal || !this._integratedTerminalInstance) {
 
-				terminal.show();
+				const options: vscode.TerminalOptions = {
+					shellPath: shell,
+					// shellArgs: this._terminalService._getDefaultShellArgs(configProvider),
+					cwd: args.cwd,
+					name: args.title || nls.localize('debug.terminal.title', "debuggee"),
+					env: args.env
+				};
+				delete args.cwd;
+				delete args.env;
+				this._integratedTerminalInstance = this._terminalService.createTerminalFromOptions(options);
+			}
 
-				return this._integratedTerminalInstance.processId.then(shellProcessId => {
+			const terminal = this._integratedTerminalInstance;
 
-					const command = prepareCommand(args, shell, configProvider);
+			terminal.show();
 
-					terminal.sendText(command, true);
+			const shellProcessId = await this._integratedTerminalInstance.processId;
+			const command = prepareCommand(args, shell, configProvider);
+			terminal.sendText(command, true);
 
-					return shellProcessId;
-				});
-			});
+			return shellProcessId;
 
 		} else if (args.kind === 'external') {
 
diff --git a/src/vs/workbench/contrib/debug/node/terminals.ts b/src/vs/workbench/contrib/debug/node/terminals.ts
index 315658072d1..7142a363971 100644
--- a/src/vs/workbench/contrib/debug/node/terminals.ts
+++ b/src/vs/workbench/contrib/debug/node/terminals.ts
@@ -29,34 +29,49 @@ export function runInExternalTerminal(args: DebugProtocol.RunInTerminalRequestAr
 	}
 }
 
-export function hasChildProcesses(processId: number): boolean {
-	if (processId) {
-		try {
-			// if shell has at least one child process, assume that shell is busy
-			if (env.isWindows) {
-				const result = cp.spawnSync('wmic', ['process', 'get', 'ParentProcessId']);
-				if (result.stdout) {
-					const pids = result.stdout.toString().split('\r\n');
-					if (!pids.some(p => parseInt(p) === processId)) {
-						return false;
-					}
-				}
-			} else {
-				const result = cp.spawnSync('/usr/bin/pgrep', ['-lP', String(processId)]);
-				if (result.stdout) {
-					const r = result.stdout.toString().trim();
-					if (r.length === 0 || r.indexOf(' tmux') >= 0) { // ignore 'tmux'; see #43683
-						return false;
-					}
-				}
-			}
+function spawnAsPromised(command: string, args: string[]): Promise<string> {
+	return new Promise((resolve, reject) => {
+		let stdout = '';
+		const child = cp.spawn(command, args);
+		if (child.pid) {
+			child.stdout.on('data', (data: Buffer) => {
+				stdout += data.toString();
+			});
 		}
-		catch (e) {
-			// silently ignore
+		child.on('error', err => {
+			reject(err);
+		});
+		child.on('close', code => {
+			resolve(stdout);
+		});
+	});
+}
+
+export function hasChildProcesses(processId: number): Promise<boolean> {
+	if (processId) {
+		// if shell has at least one child process, assume that shell is busy
+		if (env.isWindows) {
+			return spawnAsPromised('wmic', ['process', 'get', 'ParentProcessId']).then(stdout => {
+				const pids = stdout.split('\r\n');
+				return pids.some(p => parseInt(p) === processId);
+			}, error => {
+				return true;
+			});
+		} else {
+			return spawnAsPromised('/usr/bin/pgrep', ['-lP', String(processId)]).then(stdout => {
+				const r = stdout.trim();
+				if (r.length === 0 || r.indexOf(' tmux') >= 0) { // ignore 'tmux'; see #43683
+					return false;
+				} else {
+					return true;
+				}
+			}, error => {
+				return true;
+			});
 		}
 	}
 	// fall back to safe side
-	return true;
+	return Promise.resolve(true);
 }
 
 const enum ShellType { cmd, powershell, bash }