Multi-user Concurrent Access Method For Computer Interlocking Using Dynamic Thread Pool

As an important part of railway signal system,computer interlocking system plays an important role in ensuring traffic safety and improving operation efficiency.With the rapid development of railway construction,the demand for training of new railway staff,teaching of signal students and interlocking simulation experiments is gradually increasing.The traditional semi-physical simulation training system cannot carry out training anytime and anywhere due to the limitations of the site,network environment and number of personnel,so the interlocking simulation training system with C/S or B/S structure is gradually used for online training and teaching.Facing the new situation of online courses,the demand for online computer interlocking simulation training has increased significantly,which puts forward higher requirements for the concurrent performance and processing efficiency of the interlocking system on the Web server.In view of the above problems,this thesis takes B/S structure computer interlocking simulation system as the research object.Aiming at the particularity of multi-user concurrency and the complexity of data in computer interlocking,a multi-user concurrent access method based on thread pool and thread dynamic scheduling is proposed.Specifically,the research contents of this thesis are showing as follows:1)In terms of the characteristics of B/S structure computer interlocking simulation system,the problems in the case of multi-user concurrency are summarized.Then,from the perspective of concurrency in server,the theory of dynamic thread pool and the characteristics of the concurrent server models are analyzed and summarized,and the concurrent model of server-side interlocking program is determined.2)According to the characteristics of interlocking simulation system and the multithread concurrency model of server,this thesis proposes the multi-task processing model of the interlocking system based on thread pool.In terms of the core route control process in interlocking logic operations,a dynamic thread pool model in master-slave mode is constructed.In addition,the thread synchronization scheme for the multi-threaded case and the method of implementing the dynamic thread pool are proposed,and the functionalities of the thread pool are tested.3)Aiming at the problems of request accumulation and thread pool performance under multi-user concurrency,a server-side request queuing model based on queuing theory is established.According to the task characteristics in the system,the thread dynamic adjustment algorithm based on average time is proposed.Then,according to the time properties of the task,the characteristic data is collected.For each phase of load change,the thread dynamic adjustment strategy is proposed so that the thread pool can be effectively and dynamically adjusted according to the runtime parameters.4)Based on C++ programming language and VS2017 development environment,the interlocking simulation system for marshalling station is designed and developed,including the main models of communication function,data initialization,route control,non-route command processing and reading and writing to the database,and the proposed dynamic thread pool model and thread scheduling algorithm are applied to the route control process.Then,based on the Load Runner performance test tool,the test script is compiled and the multi-user concurrent scenario is designed.Finally,the performance tests of the system and the validation of the proposed model are carried out,and the test results are analyzed.The research results show that the dynamic thread pool model and thread dynamic scheduling strategy in this thesis can improve the performance of multi-user concurrent system.Depending on the number of users,the average response time of the proposed dynamic thread pool model is reduced by 1.47 % to 55.27 % compared with the fixed thread pool model and 0.27 % to 26.52 % compared with the comparison method.Additionally,both the proposed method in this thesis and the comparison method outperform the fixed thread pool model in terms of reducing the number of response failures.This thesis contains 44 figures,10 tables and 67 references.