分布式系统中的并发计算模型：Actor模型及其影响力

并发理论
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"Actors: A Model of Concurrent Computation in Distributed Systems" 是一篇具有里程碑意义的技术报告，由Gul Abdulnabi Agha撰写，发表于1985年6月，由美国海军研究办公室（Office of Naval Research）支持，作为Advanced Research Projects Agency（ARPA）的一部分。这份报告对并发理论领域产生了深远的影响，特别是在分布式系统中的并发计算模型设计。 报告的核心内容围绕着Actor模型展开，这是一种在分布式计算环境中处理并发任务的有效方式。Actor模型将计算视为一系列独立、自治且相互通信的实体，每个Actor拥有自己的状态和行为，并通过发送消息进行通信。这种模型强调了松散耦合、容错性和异步交互，使得系统能够并行处理多个任务，适应动态变化的网络环境。 在Actor模型中，重要概念包括： 1. **自主性**：每个Actor被视为一个独立的计算单元，负责处理接收到的消息并作出响应，而无需外部协调或管理。 2. **消息传递**：Actor之间的通信基于发送和接收消息，而不是共享数据，这有助于避免竞态条件和数据一致性问题。 3. **封装性**：Actor隐藏其内部状态和实现细节，仅暴露对外接口，使得它们之间可以安全地交互。 4. **不可变性和持久性**：Actor的状态是不可变的，更新是通过创建新的Actor实例完成，保证了系统的可靠性和安全性。 5. **同步与异步**：Actor模型支持异步通信，允许在等待其他Actor响应时继续执行，提高了系统的并发性能。 6. **命名空间和地址**：Actor通过唯一的名称标识，使得消息能够准确无误地发送到目标。 这份报告不仅提出了Actor模型的基本原理，还探讨了如何在分布式环境中实现和应用这种模型，以及它如何处理分布式系统中的复杂性，如故障恢复、容错机制和网络延迟。由于其在分布式计算领域的创新性和实用性，Actor模型成为了现代分布式系统设计中的核心概念之一，被广泛应用于大规模并行计算、微服务架构以及云计算等领域。

Learning Concurrent Programming in Scala, 2nd Edition

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Title: Learning Concurrent Programming in Scala, 2nd Edition Author: Aleksandar Prokopec Length: 382 pages Edition: 2nd Revised edition Language: English Publisher: Packt Publishing - ebooks Account ...

AkkaScala.pdf

2019-06-19 上传
- **Actors:** Actors are the basic units of computation in Akka. Each actor has its own thread of execution and processes messages asynchronously. - **Supervision and Monitoring:** Akka provides super...

.net orleans

2023-05-14 上传
Orleans is built on top of the Actor model, which is a way of structuring distributed systems as a collection of independent actors that communicate with each other through messages. Each actor is ...

请问为什么下列代码会报错，请修改并优化： @staticmethod def good_actors(): actors_info = {} @films_bp.route('/good_actors', methods=['GET']) def good_actors(): try: result = FilmInfo.good_actors() #直接调用Fileinfo类中构建的静态方法good_actors() logging.info('获得各年份电影数量序列') return jsonify(result) except Exception as e: logging.error('Error occurred while retrieving students from the database. Error message: {}'.format(str(e))) return jsonify({"error": str(e)}) # 查询满足条件的电影信息 films = FilmInfo.query.all() for film in films: actors_str = film.actor.strip("[]") # 去除方括号和单引号 actors = [actor.strip("'") for actor in actors_str.split(",")] # 统计演员参与的电影数量 for actor in actors: info = actors_info.get(actor, {'total_films': 0, 'best_films': 0, 'worst_films': 0, 'average_films': 0}) info['total_films'] += 1 actors_info[actor] = info # 判断电影评分并更新好片、烂片和一般片数量 if film.rate is not None: for actor in actors: info = actors_info.get(actor, {'total_films': 0, 'best_films': 0, 'worst_films': 0, 'average_films': 0}) if film.rate >= 8.5: info['best_films'] += 1 elif film.rate < 6: info['worst_films'] += 1 else: info['average_films'] += 1 actors_info[actor] = info # 计算好片占比并排序 good_actors = sorted(actors_info.items(), key=lambda x: x[1]['best_films'] / x[1]['total_films'], reverse=True)[:10] return good_actors

2023-06-02 上传
for actor in actors: info = actors_info.get(actor, {'total_films': 0, 'best_films': 0, 'worst_films': 0, 'average_films': 0}) info['total_films'] += 1 actors_info[actor] = info # 判断电影评分并...

Briefly describe the following diagrams: a.Class diagrams b.Use case diagrams: c.Objects diagrams d.Interaction diagrams

2023-03-29 上传
a. Class diagrams: Class ... Sequence diagrams show the interactions between objects in a sequential order, while communication diagrams show the interactions between objects in a more concurrent way.

如何实现换行显示def getActors(filename): actors = dict() # 打开xlsx文件，并获取第一个worksheet wb = openpyxl.load_workbook((filename)) ws = wb.worksheets[0] # 遍历Excel文件中的所有文件中的所有行 for index, row in enumerate(ws.rows): # 跳过第一行的表头 if index == 0: continue # 获取电影名称和演员列表 fileName, actor = row[0].value, row[1].value.split('/') # 遍历该电影所有演员，统计参演电影 for a in actor: actors[a] = actors.get(a, set()) actors[a].add(fileName) return actors data = getActors('实践2素材.xlsx') print(data)

2023-06-12 上传
actors[a] = actors.get(a, set()) actors[a].add(fileName) return actors data = getActors('实践2素材.xlsx') print(data, "\n") ``` 这样每次执行完 `print(data)` 后，会自动换行，使得下一行的输出与上一...

记录名单。请设计一段程序，按照学生参加演出到达的先后输入所有参加演出的学生姓名，存放到一个列表中，输入时姓名之间用“，”分隔，然后在列表中插入开始标记:“Actors”。演出结束后，输入名字可以查找某个学生，如小张，是第几个到达的算法实现的步骤和思路，Python

2023-06-03 上传
if name in actors: print(f"{name} 已在演员名单中！") continue if not actors: # 如果列表为空，则插入开始标记 actors.append("Actors") actors.append(name) print(f"{name} 已加入演员名单！") # ...

6. What is the State chart Diagram? Explain the following. a. Process b.Data Flows c. Actor d.Data Stores

2023-03-29 上传
It describes the behavior of a system over time and helps to model the dynamic aspects of a system. a. Process: A process is a set of activities that are performed to achieve a specific goal. In a ...

如何使用get_actors()函数获取当前存在于世界中的所有actors

2023-06-11 上传
您可以使用以下代码来获取当前存在于世界中的所有actors： ``` import carla # 连接到Carla服务器 client = carla.Client('localhost', 2000) client.set_timeout(10.0) # 获取当前世界 world = client.get_world...

import openpyxl import matplotlib.pyplot as plt movie_dict = {} with open('D:\\pythonProject1\\电影信息.txt', 'r',encoding='utf-8') as f: for line in f.readlines(): line = line.strip() movie_info = line.split(';') movie_name = movie_info[0] directors = movie_info[1].split(',') actors = movie_info[2].split(',') for director in directors: if director not in movie_dict: movie_dict[director] = {'movies': [movie_name], 'actors': {}} else: movie_dict[director]['movies'].append(movie_name) for actor in actors: for director in directors: if actor not in movie_dict[director]['actors']: movie_dict[director]['actors'][actor] = 1 else: movie_dict[director]['actors'][actor] += 1 wb = openpyxl.load_workbook('D:\\pythonProject1\\电影信息统计.xlsx') ws = wb.create_sheet('导演作品统计',0) ws.title = '导演作品统计' ws.cell(row=1, column=1, value='导演姓名') ws.cell(row=1, column=2, value='执导电影数量') ws.cell(row=1, column=3, value='执导电影列表') row_num = 2 for director, data in movie_dict.items(): movie_list = ','.join(data['movies']) movie_count = len(data['movies']) ws.cell(row=row_num, column=1, value=director) ws.cell(row=row_num, column=2, value=movie_count) ws.cell(row=row_num, column=3, value=movie_list) row_num += 1 wb.save('D:\\pythonProject1\\电影信息统计.xlsx') director_list = [] movie_count_list = [] for director, data in sorted(movie_dict.items(), key=lambda x: len(x[1]['movies']), reverse=True): director_list.append(director) movie_count_list.append(len(data['movies'])) plt.rcParams['font.family'] = 'sans-serif' plt.rcParams['font.sans-serif'] = ['SimHei'] fig, ax = plt.subplots() ax.barh(director_list, movie_count_list) for i, director in enumerate(director_list): max_actor = [] for actor in movie_dict[director]['actors'].keys(): if movie_dict[director]['actors'][actor]==max(movie_dict[director]['actors'].values()): max_actor.append(actor) max_actor = str(max_actor) max_actor = max_actor.rstrip(']') max_actor = max_actor.lstrip('[') ax.annotate(max_actor, xy=(movie_count_list[i], i), xytext=(movie_count_list[i]+1, i), ha='left', va='center') ax.set_xlabel('执导电影数量') ax.set_ylabel('导演姓名') ax.invert_yaxis() plt.show()请帮我解释一下上述代码，详细一点

2023-06-01 上传
for actor in actors: for director in directors: if actor not in movie_dict[director]['actors']: movie_dict[director]['actors'][actor] = 1 else: movie_dict[director]['actors'][actor] += 1 ``` 这...
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