程序代写代做代考 python js Java scheme algorithm javascript concurrency cache compiler Independent thesis, 15 HE credits, for degree of Bachelor in Computer Science
Independent thesis, 15 HE credits, for degree of Bachelor in Computer Science
Spring Term 2016
Realization of multi-threaded model of Node.JS on multi-core processors
Author： Ziteng You
School of Health and Society / School of Education and Environment [Arial 14p]
2
Author
Ziteng You
Title
Realization of multi-threaded model of Node.JS on multi-core processors
Supervisor
Nazila Hasanzade
Examiner
Dawit Mengistu
Abstract
The goal of research is to detect under multi-requests, multi-core multi-thread can improve Node.JS performance and efficiency, reflected by response time and response per second. In final testing result, we can find multi-core multi-thread system average response time less 50% than single thread system and double rps(response per second) for it.
Node.JS is a single-threaded platform. It only supports single-core. As multi-core becomes popular, the program should make use of multi-threaded computing to take full advantage of multi-core CPU technology, letting Node.JS take full advantage of multi-core is imperative.
This research uses multi-core multi-thread design and normal single thread design respectively to complete a same simulate taxi call system on Node.JS platform. The system simulated all processes that user can call a taxi, take the taxi and paying when taxi arrived on the web site. The server response for the user operation. The multi-core multi-thread model is main-sub thread model, that is use single thread to build thousands of sub-threads. The main thread only response to build sub-threads, sub-threads response for process system request. At last using test program to calculate the response time and working efficiency with this two kinds of design in setting of the special circumstances.
Keywords
Node.JS; single-threaded platform; multi-core; multi-threaded computing; taxi call system;
12
Table of Contents Page
Document page i
Abstract ii
Table of Contents iii
1 Introduction 1
1.1 Introduction of Node.JS 1
1.2 Asynchronous I/O 1
1.3 Motivation 2
2 Method 3
2.1 program analysis 3
2.2 program design 4
3 Implementation 7
3.1 System design 7
3.2 research questions simple answer 8
4 Results 9
5 Discussion and future work 10
5.1 results analysis 10
5.2 future work 10
6 Conclusion 12
7 Bibliography 13
总字数从introduction开始到conclusion结束，不包括其他部分，需要20页的内容，一个大章节结束可以换页。
1
1. Introduction
1.1 Introduction of Node.JS
Node.JS or Node is a platform can let JavaScript run on the server side. It can change JavaScript from the browser bound to run in the general server environment.
Node.JS is born for real time Web application development platform, it is from the beginning of full consideration in real-time response, large scale data requires scalable framework. This makes it abandoned the traditional platform relying on multi-thread to realize the design idea of high concurrency, and uses a single threaded asynchronous. Type I/O, event driven programming model. These characteristics not only brought a performance boost, but also reduces the complexity of multi-thread programming, thus improving the development efficiency.
Node.JS is a JavaScript running environment. In fact, it is the GoogleV8 engine package. The purpose is to execute and run JavaScript code on the server side. JavaScript has long time been a Browser based client scripting language, As a server-side language, because of its asynchronous non blocking characteristics, it is in a long connection. Advantage of working under multi-request environment is very obviously.
Node.JS on the official website is defined as: “a built in Chrome JavaScript when running on the platform to build high-speed, scalable. Node.JS network program using event driven, non blocking I/O model, so it has light weight and high efficiency. It use to build a perfect equipment running in a distributed data intensive real-time program selection Web.” the site had not limited to the contents of the presentation of many interactive and collaborative environment has been moved to the site, and this demand is still increasing rapidly. This is the so-called data intensive real-time (data-intensive real-time) applications, such as online collaborative whiteboard, multi-player online games. The web application the need for a real-time response platform for a large number of concurrent users request the support of them, this is what the Node.JS areas of expertise.
1.2 Asynchronous I/O
Threads in the implementation of the disk read and write or network communications, such as I/O operation usually takes a long time. At this time, the operating system will deprive the thread of the CPU control, so that it will suspend its execution, while the Source to other threads, such as the thread of the scheduling method called blocking. When the I/O operation is completed, the operating system will be the blocking state of the thread is released to restore its control over the I/O, so that it continues to perform.
The formula is a synchronous I/O or blocking. Asynchronous I/O or non blocking I/O will not take a blocking policy for all I/O operations.
When you encounter a I/O operation, will not wait for the completion of the I/O operation or data return, but only to I/O Request to be sent to the operating system, continue to execute the next statement. When the operating system to complete the I/O operation, it is a matter of the system will handle the event at a specific time in the form of a thread that executes the I/O operation. Asynchronous I/O, the thread must have the event loop, and constantly check that there are no pending events, in turn to be processed.
In blocking mode, a thread can only handle a task, to improve the throughput must be through multiple lines. In the non blocking mode, a thread will always perform the calculation, the CPU kernel used by this thread.
Node.JS is the biggest characteristic of the asynchronous I/O and event driven architecture design. The solution for high concurrency, the traditional architecture is a multi-thread model, also is to provide a system thread for each business logic, the time overhead of.Node.JS system through the thread switch to compensate for the synchronous I/O call when using a single thread model all the way, the asynchronous request for all I/O, to avoid the frequent context switching.
The Node maintains a queue of events in the process of implementation, the program enters the event loop in the execution waiting for the arrival of an event, each asynchronous I/O request completion will be pushed to the event queue, waiting for the process for processing.
Node.JS is a new development platform, the Node.JS user community is growing at a furious pace, and attracts every top developers. Node.JS ecosystem in many of the perfect.JavaScript is a very popular programming language, almost every computer are mounted one or more JavaScript compiler, development of most the developer of Web in its occupation career have learned JavaScript. so Node.JS technology will get better.
1.3 Motivation
Node.JS provides net, Datagram, HTTP, HTTPS of the 4 modules, respectively for the treatment of TCP (Transmission Control Protocol), UDP (User Datagram Protocol), HTTP (Hyper Text Transfer Protocol), HTTPS (Hyper Text Transfer Protocol over Secure Socket Layer), applicable to the server and the client.
The Node.JS server development of high integration, application of net module can easily build server, and can handle a large number of concurrent requests for Node.JS network and good parallel I/O intensive scene, ability to use the event loop can effectively make use of resources, to provide better service.
According to the characteristics and advantages of Node.JS, this paper proposes a Node.JS build AIS communication server based on AIS, improve the reliability of communication between base station and communication center server stability, timeliness, to meet the demand of AIS application, has application value.
In order to solve the problem of waste in the process of replication, multi-thread is introduced into the service model, so that a thread service a request. The thread of the process of the relatively low cost of many, and the data can be shared between threads, memory. The cost of the problem can be solved, and the thread pool can be used to reduce the overhead of creating and destroying threads.
2. METHOD
2.1 program analysis
The heart utilization rate is always 100% I/O to notify to the event. High system throughput in the event, because a thread blocking when there are other threads in the work. Multi-threads can make CPU Source is not blocked by the thread waste, and in the non-blocking mode, the thread will not be blocked by I/O, always in the use of CPU. Asynchronous I/O to reduce the number of threads created in the thread, the allocation of memory, the inclusion of scheduling, switch threads, memory Page CPU, cache and other aspects cost of event driven. And callback function event driven programming is a programming style that determines the execution flow of a program by an event. Processor (handler event) or event callback (callback event) to deal with the event when the event is callback.
When an event born, you call a function that is defined in the event, rather than simply return the result value. Callback function which is one of the most obvious features of Node, and this programming model means that the current process is executing I/O operation will not be blocked, therefore, multiple I/O operations can be performed in parallel, when the operation is completed, the corresponding callback event driven programming, the underlying dependency on the event loop (loop event). Event loop is essentially an event detection. There are two functions, which are triggered by the event handler and the event handler are constantly called by a structure. Circular mechanism need to detect what happened, when the event occurs, it found the corresponding callback function and tune use it.
The event loop is just a thread running within the process, when the event occurs, the event handler is able to run and will not be interrupted. There is at most one event callback function at a particular point in time. Any event handler will not be interrupted at run time.
Node.JS program from the start of the event cycle, to the end of the event loop, all the logic is the callback event Function, so Node.JS is always in the event loop, the program portal is the first event loop callback Function. The callback function of an event may issue a I/O request or a direct launch event during the execution of the event.
After the line is completed and then return to the event loop, the event loop checks that there are no pending events in the event queue to the end of the program.
single thread
Node.JS maintains the characteristics of the JavaScript in a single thread in the browser. Like multi-threaded programming that everywhere concerned about the status of the synchronization problem, there is no deadlock here, there is no upper and lower switching performance of the paper is brought on by the overhead.
Here said the Node.JS is single thread, refers to the Node.JS does not give us the ability to create a thread, all of our own code is executed by a single thread, at the same time, we can only execute one. But the host environment Node.JS is not a single thread, it will maintain an execution queue, loop detection, scheduling JavaScript threads to perform asynchronous operations, in response to events, the callback function is called by the main environment to perform, so the single thread execution does not conflict with concurrent operation.
cross platform
Node.JS in addition to the use of V8 (Google) with open source JavaScript engine for Chrome Google, as the JavaScript engine, but also the use of efficient libev and libeio library support for event driven and asynchronous I/O Node.JS biggest feature is the use of asynchronous I/O and event driven design framework. Node.JS use the single threaded model, for all of the I/O are using asynchronous request mode, to avoid the frequent context switch. Node.JS in the execution of the process will maintain an event queue, the program in the implementation of the event loop.
Waiting for the next event, each asynchronous I/O request is completed and will be pushed to the event queue, waiting for the event.
With the social networking era coming, various forms of social networking applications are continuing to emerge, the mainstream social networking applications including Facebook, Twitter and Google+, etc., each carrying hundreds of millions of daily levels of online traffic. Facing such a huge number of users concurrent access, how to continue to provide high-speed, stable, smooth high-quality user experience will become one of biggest problems to be solved for network applications.
To overcome concurrent challenges, we need to strengthen and improve the overall system design and architecture from different dimensions, from inside and outside to improve application concurrency ability comprehensively Both strengthen internal systems architecture and optimize key algorithms, but also with third-party applications external auxiliary components to improve concurrency. Compared to traditional mufti-threaded programming model and language, application service platform based on incident response mechanisms, whether from memory utilization, asynchronous I/O, and ease of programming all have an unparalleled advantage, maximize effective use of existing resources with enhancing system application concurrency.
This thesis is mainly based on Node.JS technology, combined with load balancing, distributed storage and caching techniques, presents a innovative solution to solve massive concurrent access by an efficient, stable, and scalable asynchronous and concurrent architecture. Through technical research and real-time high concurrent access performance tests, verify feasibility and innovation of network application asynchronous concurrent architecture. Finally, problems and deficiencies arising in the work are summarized, and prospected system future development.
2.2 program design
（不够详细，不需要列出表格里的方法，而是重点说明哪些重要的部分用到了什么方法，需再增加1-2页的内容）
The system is a simulate taxi call system, it connect to Google map API, simulate taxis and all actions on Google map.
There are two kinds of model, one is multi-core multi-thread model, other one is single thread model. Both of them will using to complete same taxi call system.
Figure 1. two different thread model
The multi-core multi-thread model is main-sub thread model, that is use single thread to build thousands of sub-threads. The main thread only response to build sub-threads, it averagely build sub-threads on each cores. Sub-threads response for process system request. The single thread model is a single thread process a request on the core, and next request needs waiting before it complete last request.
Server uses the express module to define a plurality of different HTTP post request. Client sends the location to server, server returns the nearest taxi to client, client displayed those taxi on Google map. Client send the destination to server, server calculate the travel distance, return to the number of kilometers and prices. Web client through the acquisition position function of HTML5 to getting user location, users can also click other place on the map to change the position. Client is responsible for interaction with the user, send post request to the server side, and display the return data.
There are some classes function definition in Table 1.
Table 1. Classes definition
index.js
main script, define the request that the server can handle
generate.js
define function that generates some points around a center
public/carbooking.html
client html page and js code
package.json
define information of this app and its dependencies
node_modules
all the library I make use of
node_modules/body-parser
used to parse http request body
node_modules/express
make use of this module to define http request handler
3.Implementation
（最好能讲到课题计划的设计是完全推翻node.js单线程从而建立一个多线程的node.js平台，但是最后发现不行，node.js必须基于单线程，所以还是做了一个主线程-子线程的模式，但是在项目计划中提到参考文献中有类似的研究，基于项目要求，必须要阐明这个情况并说明与参考文献中的不同之处。research questions 不能直接回答，而是在描述如何实现的过程中解答。需在增加1-2页的内容）
3.1 System design
Users use computer or mobile phone browser open the web page, web browser connect to Google map API, user can find taxis near their location on the map.
Then user can click “book”button, system will distribute a recently taxi and hiding other taxis on the map.
User can click anywhere on the map for his destination address, and the taxi will come to take him.
After arriving at the destination, the user click the “leave” button to finish this trip on web page, and the system will show the mileage and price according to the distance on website.
step 1 step 2
step 3 step 4
Figure 2. Program running
The test program is testing when system get 100 client parallel requests and each client send request 10 times continuously, show rps and response time of two different systems when they process each task (getposition, book, getprice, carbooking.html).
3.2 research questions simple answer
1. What are the main issues to be considered to customize Node.JS for multi-core platforms?
The main difficulty of customize Node.JS for multi-core platform is that Node.JS itself is running on a single thread, it can’t be changed to multi-thread directly. To let Node.JS run on multi-core needs to deal with a lot of sub process task allocation and coordination.
2. How can a multi-threaded extension of Node.JS be realized?
Multi-thread design is the main process only responsible for establish a number of sub processes , the actual logic processing are complete by sub processes .
Main process establish a number of sub process, these sub processes sharing server port, when network requests come in, request processing tasks are assigned to each sub process to realize processing of multiple requests at same time, to improve efficiency.
3. What is the performance gain obtained from multi-threaded Node.JS compared with the single-threaded version?
When system need response for huge multi-requests, multi-threaded system will have much more rps and much less response time than single-thread system.
4. Results
（内容太少，需再增加1-2页的内容，results analysts也应该在这里）
Because it is a simulate system, so we run it by CMD. ‘node index.js’ is for debug, ‘node test.js’ is for run test program.
When we running multi-core multi-thread system, main thread build sub-threads shown as ‘master’, next line shown how many cores have been used when system running. When single thread system running, it will show nothing.
Figure 3. Program debug
The test program running as follow:
There are 4 tasks will be test when system working. ‘done’ means how many times client send requests, blue ‘200’ is status code, ‘OK’ means how many times system system processed requests. ‘rps’ is response per second, ‘response’ is response time.
Figure 4. Testing
5. Discussion and future
5.1 results analysts
（这里应该是discussion的部分，应该是分析项目的优缺点，和相关项目的对比，需再增加1页的内容）
In test result we can see when system process task ‘book’, ‘getPrice’, ‘carbooking.html’, the muti-core multi-threads system just cost 64%, 31%, 44% response time of single thread system, and 121%, 151%, 208% rps of it. The reason of both of two system have nearly getposition efficiency is the muti-core multi-threads system need time to create sub-threads when it get requests, so it will cost some time.
Table 2. Test results
getposition
book
getPrice
carbooking.html
min(multi)
169
53
16
47
min(single)
169
80
84
131
max(multi)
200
53
49
62
max(single)
185
84
116
131
avg(multi)
184
53
30
57
avg(single)
170
83
96
131
rps(multi)
46
144
153
158
rps(single)
54
119
86
76
5.2 future work
The solution for high concurrency, the traditional architecture is a multi-thread model, is also a business logic with a system thread, thread switch through the system to compensate for the synchronous I/O call time. This method will bring the server hardware resource consumption.
Node.JS method for solving multiple request, lies in the way that the connection to the server for example, in the Node.JS of each HTTP connection will launch an operation in the Node.JS engine in the process of the event, and not for each connection to generate a new OS process. This approach is based on event driven can better save the server memory resources.
In addition, for those simple server, realized by Node.JS. Node.JS will be easy than use of the C ten + to solve the long connection request, many problems caused by the cost, so in some projects, such as online games, online chat, real-time message push function, SNS real-time communication, real-time monitoring system, can consider the application development of Node.JS.
In recent years, with the rapid development of the domestic shipping industry, the quantity of ships in navigable waters has grown rapidly. However, at the same time, the increasing quantity of ships and traffic density has a serious impact on the ecological environment and traffic safety of the navigable waters. In order to guarantee the safety of navigation, strengthen the management of the ship, The AIS base station network system covered river and coastal areas waters has been established in China. The signal has covered the important navigable waters and ports of coastal and inland countrywide.
AIS server is designed to receive AIS data with the feature of large quantity and real time. Nevertheless, in order to avoid occurrences of data congestion, missing, etc. During communication, it requires the communication links with the AIS base stations stable, reliable, and able to meet the needs of real-time communication. Currently, the most of AIS communication servers are developed with VC++ technology. They receive a variety of information via the network port or the serial interface of the PC linking with AIS base station, which is sent by sailing vessels through the network.
Node.JS is a platform which allows JavaScript to run on the server side. It has abandoned the design ideas of the traditional platform which rely on mufti-threading to achieve high concurrency. However, it adopted single-threaded, asynchronous I/O, event-driven programming model. It has turned out to be suitable for server design with the characteristic of high concurrency, real-time response and ultra-large-scale data.
6.Conclusion
（字数差不多，内容可以写的更具体一些）
This degree work is finding a suitable multi-core multi-thread system for Node.JS platform to letting Node.JS take full advantage of multi-core. From research result we can see when client have huge multi-request, multi-core multi-thread system is more high performance and efficiently than single thread system. That means if multi-core multi-thread Node.JS can be using effectively, Node.JS can be using on more broader field. Hope to see that Node.JS can get a wider range of using.
7.Bibliography
（文献的部分需要精简，不需要太多，任何在论文中引用到文献里的内容，都需要在该处标明文献的号码。尽量在以下网址中寻找：
www.hkr.se/sv/lrc/biblioteket/att-hantera-referenser/vancouver/
http://www.ub.gu.se/skriva/referensstilar/
）
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Programming in Windows
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