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Real Life Java EE Performance Tuning
 

Real Life Java EE Performance Tuning

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    Real Life Java EE Performance Tuning Real Life Java EE Performance Tuning Presentation Transcript

    • Real Life Java EE Performance Tuning Matt Brasier Principal Consultant C2B2 Consulting LTD [email_address]
    • About Me
      • Professional Services Consultant
      • Customers include
        • Red Hat (JBoss)
        • BEA
        • Cape Clear
        • Government/Finance/Telecoms
      • C2B2 Consulting
        • SOA and Java EE consultancy
        • Fast, Reliable, Manageable, Secure
    • What we will cover
      • Philosophy
        • How I approach a performance problem situation
      • Enterprise Java Performance
        • What kind of things affect performance of Enterprise Systems
      • Case Study 1
        • A new version of the application runs slowly
      • Case Study 2
        • Logging in takes a long time in the live environment
      • Case Study 3
        • The application does not scale
    • What we will learn
      • Philosophy
        • Suggestions to keep in mind when looking at a performance problem
      • Tools
        • Suggested tools for looking at a performance problem
      • Techniques
        • How to use the tools, knowledge and skills to solve your performance problem
    • Philosophy
      • ‘ A good understanding’ is the best performance tuning tool
      • Prefer common and open source tools
      • Observe, Hypothesize, Tweak, Test
      • ‘ Trust no-one’
    • Classic Java performance problems
      • Memory leaks
        • Increased GC Time
      • Poor GC or JVM Memory configuration
      • CPU bound code
      • IO bound code
      • Memory bound code
        • Increased GC time
    • Enterprise Java Performance
      • CAVEAT: Consultancy Selection Bias
      • 80/20: 80% of time finding, 20% fixing
      • Many ‘Enterprise’ Java performance problems turn out not to be ‘classic’ performance bottlenecks
        • Infrastructure/Middleware performance
      • There are many factors that can affect the performance of an enterprise system
        • Not just code
    • Enterprise Java Performance
      • Not all Java EE performance problems are classical ‘Java performance problems’
      • Common types of Java EE performance problem
        • Resource starvation
        • Threading problems
        • ‘ Suboptimal configuration’
        • Network related problems
        • Scalability problems
    • A Good Understanding
      • Consider the system as a whole
      • Know how infrastructure components work
        • Not just what they do, but how they do it
      • How do the Java EE specifications say they should work?
    • Approach
      • Understand the system
      • Understand the environment
      • Understand the situation
      • Talk to people who know
        • But trust no-one
      • Take a look for myself
      • Observe, Hypothesize, Tweak, Test
        • Rinse and repeat
    • Case Study 1
    • Case Study 1
      • Existing customer calls
        • “ We deployed a new version of the application, and it is running a lot slower”
      • The Environment
        • Sun Java 5
        • WebLogic Server 9.2 Cluster (3 nodes)
        • WebLogic Integration 9.2 Cluster (3 nodes)
        • Documentum Document Management
        • Oracle Database
        • Solaris OS
    • Case Study 1
      • The System
        • Web Application
        • WLI based workflow system
      • The situation
        • New version deployed into the performance testing environment
        • Automated performance tests indicate the application is approximately 30% slower
    • Case Study 1
      • Observe
        • No monitoring in place
        • Some alerting, but no historical data
      • Hypothesize
        • If we had more monitoring, we would stand a better chance
      • Tweak
        • Put some monitoring in place
        • Hyperic HQ from SpringSource
    • Case Study 1
      • Test
        • Re-run tests
      • Observe
        • Monitoring indicates that one server is slower
          • Handling less requests per second
          • Lots of transaction timeouts
          • Higher CPU
          • Less network traffic
      • Tweak
        • Add more monitoring to the slow server
        • Examine log files
        • Thread dumps!
    • Case Study 1
      • Hypothesize
        • Thread dumps show lots of threads in logging code waiting to write to the log file
        • Log files for the slow server have DEBUG messages in them
          • The other servers don’t
      • “ The logging configurations are identical, the servers are configured with Maven”
        • Trust no one
      • Test
        • Log in to the server and manually check the logging configuration
    • Case Study 1
      • Solution
        • Debug logging was enabled on one server
        • Turned debug logging off - the system was then about the same speed as the old release
    • Hyperic HQ
    • Hyperic HQ
      • Monitoring tool
        • Not a profiling tool
      • Historical data
        • Trends
        • Abnormal behaviour
        • ‘ Hot’ spots
      • Wide variety of data
        • JVM level statistics
        • JMX statistics
        • OS statistics
    • Thread Dumps
      • My Number 2 tool for finding performance problems
        • CTRL-BREAK in windows
        • Kill -3 on Unix/Linux
        • Jstack tool
        • Available from consoles of many application servers
      • All threads in the VM and what they are doing at that moment
    • Thread Dumps
      • A number of thread dumps over time gives a good picture
        • Any operation that appears a lot is a suspect
        • Understand what ‘normal’ thread dumps look like
      • http://java.sun.com/developer/technicalArticles/Programming/Stacktrace/
    • Thread Dump
    • Thread Dumps
      • Look near the top of each stack
      • Look for stacks with your code in them
      • Look for long stacks
      • Look for deadlocks and other threading issues
    • The Understanding
      • What does a normal WebLogic thread dump look like?
      • It is not normal to see logging code frequently in a thread dump
      • Lots of threads all waiting on a single lock object is a Bad Thing™
      • If three servers are supposed to do the same thing, their thread dumps should look similar
        • Over time
    • Lessons
      • Thread dumps hold a lot of information
      • Infrastructure configuration faults are more common than infrastructure bugs
      • Automated/continuous build and deploy solutions are no silver bullet
        • Check the results yourself
      • Believe your ‘instincts’
    • Case Study 2
    • Case Study 2
      • Customer Call
        • “ We deployed our application into the live environment and it takes several minutes for users to log in”
      • Environment
        • Apache web servers
        • WebLogic Portal 8.1 Cluster (2 nodes)
        • Oracle Database
        • Windows Server 2003
        • Bespoke Single Sign On server
    • Case Study 2
      • The System
        • Web application based on WSRP portlets
        • Oracle database storing user data
      • The Situtation
        • The first users to log-in in the morning find that it takes several minutes
        • After the first few log-ins, the application runs fine
    • Case Study 2
      • Hypothesize
        • The bespoke Single Sign On server makes me suspicious
          • Bespoke code is tested less
      • Test
        • Turn on debug logging for the SSO implementation
        • Observe timings of log messages
    • Case Study 2
      • Observe
        • The logs indicate that the SSO log-in is proceeding as expected
        • It appears that loading the users profile data from the database is taking a long time
      • Hypothesize
        • TCP timeouts when connecting to the database due to a firewall
    • Case Study 2
      • Test
        • Observe the connection pool statistics in the WebLogic console
        • The console indicates that a large number of connections have been opened during the time the application has been running
          • Connections are not normally closed and re-opened
        • See how long you need to leave the system before the problem occurs
    • Case Study 2
      • Solution
        • Discussions with the networking team indicated that there was a firewall, configured to silently terminate network connections that were Idle for 60 minutes
        • Set WebLogic to test connections after they have been idle for 50 minutes.
    • Lessons
      • Consider the system as a whole
        • Hardware
        • Networking
        • OS
        • Middleware
        • Application
    • The Understanding
      • Firewalls are often configured to silently terminate idle TCP connections
      • The TCP protocol requires that a connection is closed by both sides, or times out
        • The time out is several minutes
      • In a healthy WebLogic connection pool, the number of connections opened since the server started = the maximum number in the pool
    • Case Study 3
    • Case Study 3
      • Customer call
        • “ It takes about 20 seconds to render a page, and the performance does not scale”
      • Environment
        • WebLogic Portal 9.1 Cluster (2 nodes)
        • Oracle 10g Database
        • Red Hat Enterprise Linux
    • Case Study 3
      • The System
        • Online content delivery system
        • WebLogic Portal with a commercial set of portlets
      • The Situation
        • Two problems
          • Running the performance tests with 20 threads in JMeter is twice as slow as running the tests with 10 threads
          • Viewing a content item takes around 20 seconds
    • Case Study 3
      • Handle the two problems separately
        • They may be related, they may not be
    • Case Study 3
      • Observe
        • Viewing a content item takes around 16 seconds on my laptop
      • Test
        • Is the rendering speed dependent on the browser used?
        • Is the rendering speed dependent on the client machine?
        • What does the page source look like?
    • Case Study 3
      • Observe
        • In Opera the page renders quickly except for the table of contents on the left
        • In Firefox, the whole page renders at the same time
        • The page renders faster in IE and Opera than firefox
        • The page renders faster on faster machines
        • There is a lot of Javascript, and AJAX is used to load the table of contents
    • Case Study 3
      • Hypothesize
        • The AJAX rendering of the TOC is taking a long time, and slowing down the whole page load
      • Tweak
        • Remove the TOC from the page
        • Disable JavaScript in the browser
      • Test
        • The page renders in less than 2 seconds
    • Case Study 3
      • Hypothesize
        • JMeter does not execute the javascript, so the poor performance of JMeter is not related to the poor page load speed
    • Case Study 3
      • Solution 1
        • The portlet developers have used AJAX to render the table of contents for a content item, this is much slower than just constructing the table of contents on the server side
        • Rewrite the portlet to construct the table of contents on the server side
        • Developers sometimes select a technology to enhance their CVs, not to implement a business requirement
    • Case Study 3
      • Problem 2 – Scalability
      • Observe
        • Running the tests on JMeter with 10 users, each page response takes 5s
        • Running the test with 20 users each page response takes 12s
        • JMeter is being run on an old laptop, which is at 100% CPU in both cases
    • Case Study 3
      • Hypothesize
        • As the test machine is at 100% CPU, it is the performance of JMeter that is being measured, not the performance of WebLogic
      • Observe
        • WebLogic is running at around 2% CPU usage, with many idle threads
    • Case Study 3
      • Tweak
        • Run the test from a number of more modern machines, and make sure each one does not exceed 70% CPU
      • Observe
        • Four machines can each run 20 threads and get responses in 1.5 seconds, and WebLogic is still running at around 5% CPU and not struggling
    • Case Study 3
      • Solution
        • The problem was that the test client was not able to generate the loads requested, resulting in the performance of the test client being measured
        • Use a larger test client
    • Useful tools
      • Ethereal/Wireshark
        • Network traffic sniffer
        • See when requests/responses were sent/received
      • Firebug + YSlow
        • Firefox plugin for performance analysis
    • Lessons
      • Separate problems should initially be prioritised and investigated separately
        • Keep in mind that they may be related
      • Ensure the test system can generate the required load
        • It should have plenty of free resources available
    • Lessons
      • The consultant effect
        • Take a step back
        • Get a fresh perspective
    • The Understanding
      • A slow test client will give slow results
      • Client side rendering is usually less efficient than server side
      • WebLogic is normally fast!
    • What did we learn?
      • Simple tools can provide a lot of information
      • Understanding how the system should behave will help highlight possible causes
      • Experience is vital
        • Write a log of what you find
      • Take a step back from the problem
        • Use a second pair of eyes
    • What did we learn?
      • Philosophy
        • Understand they system as a whole
        • A deep understanding of how it should work
      • Tools
        • Thread dumps
        • Monitoring tools
        • Packet sniffing
      • Techniques
        • Observe, Hypothesize, Tweak, Test
    • Questions
    • Session Evaluation
      • Please complete a session evaluation and turn it into any conference staff member or at the registration desk. Thank you.