The Impact of Soft Resource Allocation on n-tier Application Scalability - PowerPoint Presentation

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The Impact of Soft Resource Allocation on n-tier Application Scalability - PPT Presentation

The Impact of Soft Resource Allocation on ntier Application Scalability Qingyang Wang Simon Malkowski Yasuhiko Kanemasa Deepal Jayasinghe Pengcheng Xiong Motoyuki Kawaba Lilian ID: 764554

allocation soft resource amp soft allocation amp resource parallel international ieee distributed processing 25th symposium resources 2011 hardware performance

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The Impact of Soft Resource Allocation on n-tier Application Scalability Qingyang Wang, Simon Malkowski, Yasuhiko Kanemasa, Deepal Jayasinghe, Pengcheng Xiong, Motoyuki Kawaba, Lilian Harada, Calton Pu

25th IEEE International Parallel & Distributed Processing Symposium 19 May 2011OutlineBackground & MotivationBackgroundMotivational experimentPerformance Impact of Soft Resource Allocation Over-allocation of soft resourcesUnder-allocation of soft resourcesSpecial case of under-allocation SolutionA practical algorithm for good soft resource allocationConclusion & Future Works

25th IEEE International Parallel & Distributed Processing Symposium 19 May 2011 Cloud Computing Environment Good performance + Cost efficiency Scaling applications on demand High throughput + low response time High resource utilization

Soft resources in n-tier systemsThreads, database connections, TCP connections, locks, etc. Soft Resource Allocation25th IEEE International Parallel & Distributed Processing Symposium19 May 2011 Is it okay to duplicate the same configuration of soft resource allocation?

RUBBoS benchmarkBulletin board system like Slashdot (www.slashdot.org)Typical 3-tier or 4-tier architectureTwo types of workloadBrowsing onlyRead/Write mix24 web interactionsC-JDBCMiddleware for database scale-outRead: act as a load-balancerWrite: send a request to all databases to keep consistencyExperimental Environment (1) 25th IEEE International Parallel & Distributed Processing Symposium 19 May 2011

Emulab (http://www.emulab.net)Relatively modest testbed originally for network researchVirtual network & physical machines (not VM)Experimental Environment (2)25th IEEE International Parallel & Distributed Processing Symposium 19 May 2011 Hardware Specifications Server type PC3000 in Emulab Processor Xeon 3GHz 64bit Memory 2GB Network 1Gbps Disk 2 x 146GB 10,000rpm

Software setups Experimental Environment (3)25th IEEE International Parallel & Distributed Processing Symposium19 May 2011FunctionSoftware Web server Apache 2.0.54 Application server Apache Tomcat 5.5.17 DB clustering middleware C-JDBC 2.0.2 Database server MySQL 5.0.51a Java Sun jdk1.6.0_14 Operating system Redhat FC4 System Monitor Sysstat 7.0.2

Notation Experimental Environment (4)25th IEEE International Parallel & Distributed Processing Symposium19 May 2011400-6-200 1 / 3 / 1 / 2 configuration

25th IEEE International Parallel & Distributed Processing Symposium 19 May 2011Result of Motivational Experiment Scale out

Hardware configuration 2 25th IEEE International Parallel & Distributed Processing Symposium 19 May 2011 Challenge Hardware configuration Soft resource allocation Hardware configuration 1 Soft resource allocation 1 Thread pool, DB connection pool Thread pool, DB connection pool Soft resource allocation 2 Good performance Bad performance Good performance Scale out How to choose a reasonable soft resource allocation to match the hardware configuration?

Evaluate two important soft resources ThreadsDatabase connectionsShow their performance impact on n-tier applicationsOver-allocation & under-allocation casesSpecial case of under-allocationIntroduce a practical way to choose a reasonable allocation of soft resourcesFocus of This Paper 25th IEEE International Parallel & Distributed Processing Symposium 19 May 2011

25th IEEE International Parallel & Distributed Processing Symposium 19 May 2011Performance Loss due to Soft Resource Over-allocation (1)400-200-6 Sensitivity analysis : change DB Connection pool size in Tomcat

25th IEEE International Parallel & Distributed Processing Symposium 19 May 2011 50 6 100 200 Performance degradation Goodput 1/4/1/4 CPU utilization in CJDBC 6 200 Throughput with response time boundary Performance Loss due to Soft Resource Over-allocation (2) High allocation of DB connections in Tomcat degrades the system performance

25th IEEE International Parallel & Distributed Processing Symposium 19 May 2011JVM Garbage Collection CostsOver-allocation of soft resources causes waste of critical hardware resources 200 6 8% more time used for GC over experimental time JVM Garbage Collection in CJDBC

25th IEEE International Parallel & Distributed Processing Symposium 19 May 2011Performance Loss due to Soft Resource Under-allocation (1)400-6-200 Sensitivity analysis : change thread pool size in Tomcat

6 200 25th IEEE International Parallel & Distributed Processing Symposium 19 May 2011 Performance Loss due to Soft Resource Under-allocation (2) Goodput 1/2/1/2 20 10 CPU utilization of Tomcat 20 6 Under-allocation of soft resources causes inefficient utilization of hardware resources

25th IEEE International Parallel & Distributed Processing Symposium 19 May 2011Special Case of Soft Resource Under-allocation30-6-100 Sensitivity analysis : change thread pool size in Apache

30 -6-100400-6-100 50-6-100 100 -6-10025th IEEE International Parallel & Distributed Processing Symposium 19 May 2011 Performance Loss due to Under-allocation of Apache Threads Goodput 1/4/1/4 CPU utilization in CJDBC 30 -6-100 400 -6-100 Low allocation of Apache threads degrades the system performance

25th IEEE International Parallel & Distributed Processing Symposium 19 May 2011Non-Trivial Correlation between Apache and Tomcat Threads (1)30-6-100 30 > 6 * 4 Why are 30 threads in Apache not enough?

25th IEEE International Parallel & Distributed Processing Symposium 19 May 2011Non-Trivial Correlation between Apache and Tomcat Threads (2) Waiting for TCP FIN reply from the client

25th IEEE International Parallel & Distributed Processing Symposium 19 May 2011Non-Trivial Correlation between Apache and Tomcat Threads (3) The long waiting time for FIN reply from clients is unpredictable and frequently happens under high workload Waiting for TCP FIN reply from client

Concurrency for 30-6-100Concurrency for 400 -6-100 Large number of soft resources in front tier acts as a buffer providing stable workload for lower tiers25th IEEE International Parallel & Distributed Processing Symposium 19 May 2011 Concurrency of Apache Threads Connecting to Tomcat

25th IEEE International Parallel & Distributed Processing Symposium 19 May 2011Summary of ExperimentsOver-allocation of soft resources causes waste of critical hardware resourcesUnder-allocation of soft resources causes inefficient utilization of hardware resources Large number of soft resources in front tier acts as a buffer providing stable workload for downstream tiers

25th IEEE International Parallel & Distributed Processing Symposium 19 May 2011Soft Resource Allocation AlgorithmKey idea: allocating soft resources globally to utilize the critical hardware resource as efficiently as possible

Identifying the critical hardware resource first Soft Resource Allocation Algorithm (1)25th IEEE International Parallel & Distributed Processing Symposium19 May 2011 (1) Bottleneck server

Identifying the critical hardware resource first Allocating proper soft resources for the bottleneck serverSoft Resource Allocation Algorithm (2)25th IEEE International Parallel & Distributed Processing Symposium 19 May 2011 Throughput knee Minimum Saturation workload (2) Ave. number of active threads (1) Bottleneck server

(3) Dependency between current tier and bottleneck tier Identifying the critical hardware resource firstAllocating proper soft resources for the bottleneck serverAllocating proper amount soft resources in other tiers Soft Resource Allocation Algorithm (3) 25th IEEE International Parallel & Distributed Processing Symposium 19 May 2011 (2) Ave. number of active threads (1) Bottleneck server

Achieving good performance by scaling n-tier applications in Cloud requires a unified exploration of both hardware and softwareContributions: We showed allocation of soft resources has a big impact on the total performance of an N-tier system We showed to decide a proper soft-resources allocation is a complex problem, especially in cloud environments which requires dynamic scaling-out/inWe gave a practical algorithm for proper soft resource allocation 25th IEEE International Parallel & Distributed Processing Symposium 19 May 2011 Conclusion

25th IEEE International Parallel & Distributed Processing Symposium 19 May 2011Future WorkExplore more soft resources such as locks, buffer/queueExplore more efficient ways to find proper soft resource allocationExplore the impact of soft resource allocation in virtualized environment

Thank You. Any Questions? Qingyang Wang qywang @cc.gatech.edu