WebSphere Application Server V6.1 Performance and Tuning

Transcription

1 IBM Software Group WebSphere Application Server V6.1 Performance and Tuning Surya Duggirala: Bhushan Lokhande: WebSphere Support Technical Exchange

2 Purpose of meeting After completing this session, you should be able to: Know the performance improvements that went in WebSphere Application Server (WAS) 6.1 base runtime Understand how to tune and use key J2EE components JDK and other runtime components for optimal performance with WAS 6.1 WebSphere Support Technical Exchange 2

3 Agenda What s New for V6.1 Performance New performance features of IBM Java 5.0 JDK Performance Tuning EJB and other runtime tuning WebSphere Support Technical Exchange 3

4 J2EE Performance History J2EE Performance (JSP, Servlets, and EJBs) has steadily improved with each WebSphere release. WAS 5.0 Moved from J2EE 1.2 to J2EE 1.3 WAS 5.1 Internal optimizations and JDK 1.4.X WAS 6.0 Moved from J2EE 1.3 to J2EE 1.4 WAS 6.1 Internal optimizations and JDK 1.5 In five years throughput on the exact same hardware has gone up over 4x! throughput (req/sec) Trade J2EE Application Performance through the years J2EE X Factor Improvement WAS WAS WAS WAS WAS 6.1 WebSphere Support Technical Exchange 4

5 What s New for V6.1 Performance Improved performance with Java version 1.5 Java Virtual Machine (JVM ) enhancements New memory allocation and garbage collection schemes Reduced lock contention for improved ORB scalability Improved Web Container performance/scalability AIO Code path improvements Caching enhancements Improved HTTP session replication JSP engine improvements EJB improvements Code path improvements Light weight Entity Bean Higher performance access intent settings Optimizations to persistence manager Read-only beans Improved Web services performance Improved deserialization Web services caching Other web services code path improvements In-process messaging Code path improvements Switch to use file system as message store along with relational database Improved Dynamic Fragment Caching DMap caching improvements Startup Time and Memory Footprint improvements (With IBM JDK) Sharing of classes across JVM s Class cache in shared memory for faster startup time Runtime improvements Improvements to BoundedBuffer WebSphere Support Technical Exchange 5

6 Cross-Platform Comparisons Be careful with cross-platform comparisons Differences exist across platforms Hardware examples are CPU clock speed 32 bit and 64 bit architectures number of processors and cores per processor bus speed L2 cache disk seek access time I/O wait times tuning Software examples are OS paging process priorities tuning WebSphere Support Technical Exchange 6

7 Cross-Platform Comparison of Trade EJB Throughput Cross-Platform Comparison of Trade EJB Throughput 2500 V6.02 V6.1 reqs/second HPUX Solaris Windows Linux i5/os AIX CPU% WAS CPU% DB R/T ms System configuration Workload: Trade-EJB-sync, port 9080, no dynamic cache, 25 clients per driver for 50 total Driver: Workload driver on (2) IBM x330 2 cores 1.2 GHz Intel P3, SLES Linux 9.0 Solaris SUT: Sun T2000, 8 cores, 1.0GHz 16 GB RAM, Sun Solaris Release 10 HP-UX SUT: HP rx6600 Itanium, 4 cores, 1.6 GHz, 8GB Memory, HP-UX B (64-bit) Windows SUT: Intel S3E3140-SDP Xeon MP 2MB L2 cache per core, 8 cores, 3.0 GHz (HT Enabled), 8GB RAM, Windows 2003 Server Enterprise Edition Linux SUT: Intel S3E3140-SDP Xeon MP 2MB L2 cache per core, 8 cores, 3.0 GHz (HT Enabled), 8GB RAM, SLES 9.0 x86_64 i5/os SUT: System i5 model 550, 4 cores 1.9 GHz (SMT), 32 GB Memory, i5/os V5R4 AIX SUT: pseries p5 p570, 4 cores, 1.9 GHz (SMT), 32 GB RAM, AIX 5.3 ML3 Performance gains are significant on AIX, Linux, i5/os, and Windows platforms due to enhancements in IBM JVM 5.0 Improvements in the Web and EJB containers provides better throughput and response time WebSphere Support Technical Exchange 7

8 New performance features of IBM Java 5.0 Superior JIT (Just in time) compiler multiple optimization levels, multiple recompilations of the same method, many new optimizations dynamic observation of the execution of code via profiling to aggressively improve hot code Interpreter profiling to adapt compilation to compiled methods for block reordering, loop unrolling, etc. Asynchronous compilation Compilation of Java methods proceeds on a background thread Other application threads do not have to wait to execute the method Improves startup time of heavily multithreaded applications on SMPs Garbage collector enhancements Incorporates for the first time generational garbage collection No residual fragmentation All other fragmentation can be removed in Java 5 using compaction cycle in GC WebSphere Support Technical Exchange 8

9 JDK Performance Tuning Key Parameters IBM JVM: Heap size (-Xms / -Xmx) is key setting that effects performance most and should get you near 80% of your maximum performance: Tune heap size so that average time between garbage collections should be at least 5-6 times the average duration of a single garbage collection Typical low end bound on frequency of GC s is 10sec Typical high end bound on duration of GC s is 1-2sec Ensure that you are setting your minimum/maximum heaps values so that you are running java process under you physical memory limitation. Java process size = Java Heap + Native Heap. # Native Heap = VM resources + Underpin Java objects + JNI code allocations # Monitor process address space (via perfmon, svmon) to determine size of native heap. Sun/HP JVM: To get optimal performance you need to tune the garbage collector A new JVM setting was introduced in JDK that for Sun has shown promise in automatically tuning the rest of heap settings for your machine -XX:+AggresiveHeap is issued at the command line and it makes decisions on GC algorithms, Young/Old Generation spaces, and other resources to use. One must also issue the server parameter to the Sun/HP JVMs to get them to run in their highest performing mode. WebSphere Support Technical Exchange 9

10 GC Policy: Parallel GC (optthruput) Parallel Mark Sweep Collector, with compaction avoidance Created to make use of additional processors on server systems Designed to increase performance for SMP and not degrade performance for uni-processor systems Optimized for Throughput best policy for batch type applications Consists of a single flat Java heap: WebSphere Support Technical Exchange 10

11 GC Policy: Concurrent GC (optavgpause) Reduces and makes more consistent the time spent inside Stop the World GC Reduction usually between 90 and 95% Achieved by carrying out some of the STW work whilst application is running 1.4.2: Concurrent Marking 5.0: Concurrent Marking and Concurrent Sweeping Slight overhead on throughput for greatly reduced STW times Policy is ideal for systems with responsiveness criteria e.g. Portal applications WebSphere Support Technical Exchange 11

12 GC Policy: Subpooling (subpool) Goals: Reduce allocation lock contention by distributing free memory into multiple lists Reduce allocation contention through use of atomic operations instead of a heap lock Prevent premature garbage collections by using a best fit (or closer to best fit) policy instead of address ordered Externally, no real difference to the JIT/VM Allocations are still TLH based Incremental TLH clearing, but that isn t Subpool specific Ideal for very large SMP systems where large amounts data is being allocated Does not work on all platforms Z and AIX WebSphere Support Technical Exchange 12

13 GC Policy: Generational and Concurrent GC (gencon) Generational local collection with a partially concurrent global collector Motivation: Objects die young so focus collection efforts on recently created objects Generational allows a better return on investment (less effort, better reward) Reduce large pause times Divide the heap up into a two areas: new (nursery) and old (tenure) Perform allocates from the new area Collections focus on the new area Objects that survive a number of collects in new area are promoted to old area (tenured) Ideal for transactional workloads WebSphere Support Technical Exchange 13

14 GC Policy: Generational and Concurrent GC (gencon) Minor Collection The young generation is a specific area of the heap known as the nursery. It is further split into two sections: the allocate space and the survivor space. Objects are born (created) in the allocate space New area (nursery) collected by a semi-space copying collector (Scavenge operation) Reduction of fragmentation (improved allocation rates) Time relative to amount of live data (not size of new area) Major Collection Takes place in the new and old generation and uses the normal mark/sweep (+compact) algorithm A B Survivor Allocate Survivor Allocate C Allocate Survivor Tenured WebSphere Support Technical Exchange 14

15 Runtime Performance Tuning How to tune a generational GC setup General We need to consider the respective size of the nursery and the tenured space. Two approaches Dynamic Specify the mininum and maximum heap size (e.g. Xms512m Xmx1024m). The sizes of the young and tenured generations will self adjust over time based on memory pressure. Default self adjusting behavior is usually sufficient May not give highly optimal performance. Could be good for low response times. Fixed Be more specific on the nursery and/or tenured space sizes. Recommended approach for performance sensitive, server-side applications. WebSphere Support Technical Exchange 15

16 Runtime Performance Tuning How to tune a generation GC setup Heap size options Heap Size options Allow to expand/contract -XmnsAm -XmnxBm -XmosBm -XmoxCm A B C Fix both nursery and tenured space -XmnAm Nursery 0 A 0 -XmoBm Tenured B This is Hybrid option, which will specify both minimum and maximum as same. Locks the areas For better performance lock the nursery space. Don't let it grow/shrink. There is significant amount of overhead involved with shrinking/expanding the new space Note that the fixed size options are not compatible with the minimum and maximum settings. If you specify both the JVM will not start and will throw an error message. WebSphere Support Technical Exchange 16

17 Runtime Performance Tuning How to tune a generational GC setup Setting the tenured/old space The tenured space must be large enough to hold all persistent data of the application. Too small will cause excessive GC or even out of memory conditions. For a typical WebSphere Application Server application this is ~ MB. One way to determine the tenure space size is to look at the amount of free heap exists after each GC in default mode Analyze verbosegc to understand how frequently the tenured space gets collected. An optimal generational application will never have a collection in the tenured space. In the lab some WAS applications collect every ~15min. Setting the nursery/new generation space Large nursery good for throughput Small nursery good for low pause times Good WebSphere performance (throughput) requires a reasonable large nursery. A good starting point would be 512 megabytes Analyze verbosegc to understand frequency and length of scavenges. WebSphere Support Technical Exchange 17

18 Runtime Performance Tuning How to tune a generational GC setup Test case WebSphere Support Technical Exchange 18

19 EJB and Runtime Tuning Lightweight Local Mode for entity beans BoundedBuffer Tuning WebSphere Support Technical Exchange 19

20 EJB Tuning Lightweight Local Mode for entity beans What is Lightweight Local Mode? A special operational mode to improve performance of Entity Beans Based on EJB 3.0 POJO Model 30 40% reduction in preinvoke & postinvoke instruction usage Used in Session Façade pattern Entity Bean local home and local business methods are called from within methods of a Stateless Session Bean or Stateful Session Bean The SessionBean methods provide security control and transaction demarcation for the EntityBean(s) accessed by the SessionBean Pre-conditions The bean implements an EJB local interface No security authorization is defined on the Entity Bean The classes of the Calling bean and called Entity Bean were loaded by the same JVM The Entity Bean methods do not call the WebSphere-specific Internationalization or workarea services Entity Bean's local methods use the following transaction attributes: REQUIRED,SUPPORTS, or MANDATORY WebSphere Support Technical Exchange 20

21 EJB Tuning (..contd) Lightweight Local Mode for entity beans How to apply this mode to an Entity Bean EJB Environment variable technique Select the EJB deployment descriptor of the EntityBean you want to work with Create an EJB environment variable with the name com/ibm/websphere/ejbcontainer/lightweightlocal Set the type of this variable to java.lang.boolean Set the value of this variable to True to apply lightweight local mode to this EntityBean, or False to enable the default behavior Marker interface technique code your bean implementation class to implement the interface com.ibm.websphere.ejbcontainer.lightweightlocal For details, see the com.ibm.websphere.ejbcontainer package in the Reference > Developer > API documentation section of the information center WebSphere Support Technical Exchange 21

22 Runtime Tuning New BoundedBuffer design IBM Software Group New high efficiency programming Model for runtime Efficient design to reduce the latency and contention on the buffer's lock structures, hence increasing both speed and throughput New Design Only one counter (numberofusedslots) is used for both put and take This counter is declared as AtomicInteger which has the advantage of fast atomic increment and decrement operations reducing the latency Expand operation holds both main locks concurrently avoiding the race condition WebSphere Support Technical Exchange 22

23 Runtime Tuning How to tune new BoundedBuffer Tuning Access to the BoundedBuffer is most efficient if the buffer is neither empty nor full First Tune the other system parameters like Web Container and ORB threads There are 5 parameters to tune BoundedBuffer com.ibm.ws.util.boundedbuffer.spins_take =4 com.ibm.ws.util.boundedbuffer.yield_take =false com.ibm.ws.util.boundedbuffer.spins_put =4 com.ibm.ws.util.boundedbuffer.yield_put =false com.ibm.ws.util.boundedbuffer.wait =10000 WebSphere Support Technical Exchange 23

24 Summary WebSphere Application Server V6.1 provides improved performance due to: Improvements to Java and the new IBM JDK 1.5 Improvements to the Web Container and introduction of AIO Improvements to the EJB Container Improvements to Web Services Improvements to the startup/ memory footprint. The generational collector can provide superior performance, both in throughput and latency, for many workloads (especially transactional workloads) Generational Collector default self adjusting behavior is usually sufficient If the theory and goals of tuning are understood and its behavior monitored via verbosegc then several controls can be utilized to fine tune the collector for optimum performance. Use Lightweight Local mode for Entity Beans to improve performance where ever possible Even though the new BoundedBuffer is tuned optimally out of the box, tuning this further may improve performance for certain workloads and operating system WebSphere Support Technical Exchange 24

25 Additional WebSphere Product Resources Discover the latest trends in WebSphere Technology and implementation, participate in technically-focused briefings, webcasts and podcasts at: Learn about other upcoming webcasts, conferences and events: Join the Global WebSphere User Group Community: Access key product show-me demos and tutorials by visiting IBM Education Assistant: View a Flash replay with step-by-step instructions for using the Electronic Service Request (ESR) tool for submitting problems electronically: Sign up to receive weekly technical My support s: WebSphere Support Technical Exchange 25

26 Additional Resources Link to previous WAS 6 Advance tuning presentations - Previous Webcasts Webcast replay: WebSphere Application Server V6.0 Advanced Performance Tuning Part 1 Webcast replay: WebSphere Application Server V6.0 Advanced Performance Tuning Part 2 WebSphere Application Server Performance Web Site Diagnostic guides for IBM JVMs An overview of the new functions and features in the IBM implementation of Java Tools available to visualize verbose GC logs GC Collector from IBM AlphaWorks: PMAT from ISA : evtk from ISA (recommended): Documentation and tuning for the Sun JVM Wealth of information on tuning and configuring the HPUX JVM WebSphere Support Technical Exchange 26

27 Questions and Answers Thank You!! WebSphere Support Technical Exchange 27