python - 关于Flask中全局变量问题

问题描述

Q：看了一个Flask的简单教程，但是有一个问题不明白。Flask中app的全局变量在多个客户端访问的情况下不会出错吗?比如下面代码中tasks列表在多个客户端同时访问的时候不会出错吗？我用两个客户端进行删除操作的时候，没有发现问题，但是在并发更高的情况下会不会出现问题，表示不理解，求解释。

PS：下面代码在python3.0中，需要把task = filter(lambda t: t[’id’] == task_id, tasks)

if len(task) == 0:

改成task = filter(lambda t: t[’id’] == task_id, tasks)task = list(task)

if len(task) == 0:

#!flask/bin/pythonfrom flask import Flask, jsonify, abort, request, make_response, url_forfrom flask.ext.httpauth import HTTPBasicAuthapp = Flask(__name__, static_url_path = '')auth = HTTPBasicAuth()@auth.get_passworddef get_password(username): if username == ’miguel’:return ’python’ return None@auth.error_handlerdef unauthorized(): return make_response(jsonify( { ’error’: ’Unauthorized access’ } ), 403) # return 403 instead of 401 to prevent browsers from displaying the default auth dialog @app.errorhandler(400)def not_found(error): return make_response(jsonify( { ’error’: ’Bad request’ } ), 400)@app.errorhandler(404)def not_found(error): return make_response(jsonify( { ’error’: ’Not found’ } ), 404)tasks = [ {’id’: 1,’title’: u’Buy groceries’,’description’: u’Milk, Cheese, Pizza, Fruit, Tylenol’, ’done’: False }, {’id’: 2,’title’: u’Learn Python’,’description’: u’Need to find a good Python tutorial on the web’, ’done’: False }]def make_public_task(task): new_task = {} for field in task:if field == ’id’: new_task[’uri’] = url_for(’get_task’, task_id = task[’id’], _external = True)else: new_task[field] = task[field] return new_task @app.route(’/todo/api/v1.0/tasks’, methods = [’GET’])@auth.login_requireddef get_tasks(): return jsonify( { ’tasks’: map(make_public_task, tasks) } )@app.route(’/todo/api/v1.0/tasks/<int:task_id>’, methods = [’GET’])@auth.login_requireddef get_task(task_id): task = filter(lambda t: t[’id’] == task_id, tasks) if len(task) == 0:abort(404) return jsonify( { ’task’: make_public_task(task[0]) } )@app.route(’/todo/api/v1.0/tasks’, methods = [’POST’])@auth.login_requireddef create_task(): if not request.json or not ’title’ in request.json:abort(400) task = {’id’: tasks[-1][’id’] + 1,’title’: request.json[’title’],’description’: request.json.get(’description’, ''),’done’: False } tasks.append(task) return jsonify( { ’task’: make_public_task(task) } ), 201@app.route(’/todo/api/v1.0/tasks/<int:task_id>’, methods = [’PUT’])@auth.login_requireddef update_task(task_id): task = filter(lambda t: t[’id’] == task_id, tasks) if len(task) == 0:abort(404) if not request.json:abort(400) if ’title’ in request.json and type(request.json[’title’]) != unicode:abort(400) if ’description’ in request.json and type(request.json[’description’]) is not unicode:abort(400) if ’done’ in request.json and type(request.json[’done’]) is not bool:abort(400) task[0][’title’] = request.json.get(’title’, task[0][’title’]) task[0][’description’] = request.json.get(’description’, task[0][’description’]) task[0][’done’] = request.json.get(’done’, task[0][’done’]) return jsonify( { ’task’: make_public_task(task[0]) } ) @app.route(’/todo/api/v1.0/tasks/<int:task_id>’, methods = [’DELETE’])@auth.login_requireddef delete_task(task_id): task = filter(lambda t: t[’id’] == task_id, tasks) if len(task) == 0:abort(404) tasks.remove(task[0]) return jsonify( { ’result’: True } ) if __name__ == ’__main__’: app.run(debug = True)

项目链接

问题解答

http://blog.csdn.net/yueguang...

http://www.cnblogs.com/lqminn...