How To Get The Most Out Of Your Hibernate, JBoss EAP 7 Application (Ståle Pedersen)
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The document outlines methodologies and tools for optimizing the performance of Hibernate applications on JBoss EAP 7, covering monitoring, profiling, tuning, and benchmarking techniques. It discusses various performance bottlenecks, JVM-level optimizations, and specific improvements in Hibernate 5, including memory usage reduction and enhanced caching. It also emphasizes the importance of measuring and analyzing performance metrics while addressing common pitfalls in benchmarking processes.
![jmap
Prints Java shared object memory maps or heap memory
● Several different options
○ histo[:live] – Prints a histogram of the heap, list classes, number of objects, size
○ heap – Prints information regarding heap status and usage
○ dump:<dump-options> – Dump java heap
○ No options will print shared object mappings](https://image.slidesharecdn.com/devnationperformance2016-160801160746/85/How-To-Get-The-Most-Out-Of-Your-Hibernate-JBoss-EAP-7-Application-Stale-Pedersen-32-320.jpg)
![Sampling CPU Profilers
[survey made by RebelLabs]](https://image.slidesharecdn.com/devnationperformance2016-160801160746/85/How-To-Get-The-Most-Out-Of-Your-Hibernate-JBoss-EAP-7-Application-Stale-Pedersen-44-320.jpg)
How To Get The Most Out Of Your Hibernate, JBoss EAP 7 Application (Ståle Pedersen)
- 2. How to get the most of of your Hibernate, JBoss EAP 7 application Ståle Pedersen
- 3. Agenda Lessons of what we've learned…. ● Methodology ● Tools ● Profiling ● Benchmarking ● EAP 7 Performance improvements
- 5. Methodology What ● What prevents my application from running faster? ○ Monitoring
- 6. Methodology What -> Where ● What prevents my application from running faster? ○ Monitoring ● Where does it hide? ○ Profiling
- 7. Methodology What -> Where -> How ● What prevents my application from running faster? ○ Monitoring ● Where does it hide? ○ Profiling ● How can we improve performance? ○ tuning/optimizing
- 8. Methodology Top down approach ● System Level ○ Disks, CPU, Memory, Network, ....
- 9. Methodology Top down approach ● System Level ○ Disks, CPU, Memory, Network, .... ● JVM Level ○ Heap, GC, JIT, Classloading, ….
- 10. Methodology Top down approach ● System Level ○ Disks, CPU, Memory, Network, .... ● JVM Level ○ Heap, GC, JIT, Classloading, …. ● Application Level ○ APIs, Algorithms, Threading, ….
- 11. Methodology What are we looking for?
- 12. Methodology What are we looking for? ● Lot of %sys ○ Networking, scheduling, swapping
- 13. Methodology What are we looking for? ● Lot of %sys ○ Networking, scheduling, swapping ● Lot of %iowait ○ Disk activity, not enough disk block/caches
- 14. Methodology What are we looking for? ● Lot of %sys ○ Networking, scheduling, swapping ● Lot of %iowait ○ Disk activity, not enough disk block/caches ● Lot of %irq, %soft ○ Interacting with devices
- 15. Methodology What are we looking for? ● Lot of %sys ○ Networking, scheduling, swapping ● Lot of %iowait ○ Disk activity, not enough disk block/caches ● Lot of %irq, %soft ○ Interacting with devices ● Lot of %idle ○ Few (runnable) threads, big GC pauses
- 16. Methodology What are we looking for? ● Lot of %sys ○ Networking, scheduling, swapping ● Lot of %iowait ○ Disk activity, not enough disk block/caches ● Lot of %irq, %soft ○ Interacting with devices ● Lot of %idle ○ Few (runnable) threads, big GC pauses ● Lot of %user ○ No need to use profiling until you have high %user time
- 17. Tools
- 18. Tools Tool types ● Observability, safe, depending on overhead ● Benchmarking, load testing. Difficult to do in a production environment ● Tuning, changes could hurt performance, perhaps not now or at the current load, but later
- 19. Tools ● Tool types ○ Observability, basic ■ top ■ dmesg ■ free ■ vmstat ■ iostat ■ mpstat ■ sar
- 20. top System summary, list processes or threads ● Can miss processes that do not last long enough to be caught ● Will most often consume a fair bit of CPU ● Default summary CPU usage, use “1” to get a better view of cores
- 21. dmesg Print kernel ring buffer ● Display system messages ● An error tool that can give info why an application is slow/dies ● Eg: OOM issues, filehandles, TCP errors, ++
- 22. free Memory usage ● Give a quick overview over memory usage ● Virtual page, and block devices I/O cache
- 23. vmstat Virtual memory stat ● r - number of processes running (waiting to run), should be < num cpus ● b - number of processes sleeping ● free – idle memory, should be high ● si, so – memory swapped to/form disk, should be 0 ● cpu, percentages of total CPU time ○ user time, system time, idle, waiting for I/O and stolen time ○ system time used for I/O
- 24. mpstat Processors statistics ● Gives a good overview of CPU time ● Comparable to top (with 1 pressed to show all CPU's), but use less CPU
- 25. sar System activity information ● Check network throughput ● rxpck/s, txpck/s – total number of packets received/transmitted per second ● Use EDEV for statistics on failures the network devices are reporting
- 26. sar System activity information ● Reports TCP network traffic and errors ● active/s – number of local initiated TCP connections per second ● passive/s – number of remote initiated TCP connections per second ● retrans/s – number of segments retransmitted per second
- 27. iostat Monitor system I/O devices
- 28. Java Tools Observing Java applications
- 29. Java Tools Observing Java applications ● Not as many tools out of the box
- 30. Java Tools Observing Java applications ● Not as many tools out of the box ○ but they are powerful ● jstack, jstat, jcmd, jps, jmap, jconsole, jvisualvm
- 31. jstack Prints Java thread stack traces for a Java process ● Useful to quickly look at the current state of the threads
- 32. jmap Prints Java shared object memory maps or heap memory ● Several different options ○ histo[:live] – Prints a histogram of the heap, list classes, number of objects, size ○ heap – Prints information regarding heap status and usage ○ dump:<dump-options> – Dump java heap ○ No options will print shared object mappings
- 33. jstat Monitor JVM statistics; gc, compilations, classes ● Many useful options: class, compiler, gc, gccapacity, gccause, gcnew, gcold, gcutil, ... ○ class – number of classes loaded/unloaded, Kbytes loaded/unloaded ○ compiler - number of compiled, failed, invalid compilations, with failedtype/method ○ gcutil – garbage collection statistics; survivor space 0,1, eden, old space, permanent, young generation, gc collection time, …
- 34. Byteman A tool that simplifies Java tracing, monitoring and testing ● http://byteman.jboss.org/ RULE ServerLogger_serverStopped CLASS org.jboss.as.server.ApplicationServerService METHOD stop AT ENTRY IF TRUE DO openTrace("stop","/tmp/stop.log"); traceStack("stop: "+Thread.currentThread.getName()+"n","stop"); ENDRULE
- 35. Java Tools What have we learned ● Java have decent monitoring tools out of the box ● Not as easy to use, but powerful ● Gives a lot of information as a (fairly) low cost ● Also included ○ VisualVM ○ JConsole
- 36. Tools Final thought ● Which tool you use/prefer is not important
- 37. Tools Final thought ● Which tool you use/prefer is not important ○ What is important is that you can measure everything
- 38. Profilers
- 39. Profilers High CPU load Where is it?
- 40. Profilers High CPU load Can profilers help?
- 41. Profilers High CPU load Can profilers help? Profilers (try) to show “where” application time is spent
- 42. CPU Profiling Limitations ● Many problems are not CPU Bound ○ Networking ○ Database ○ Remote Services ○ I/O ○ Garbage Collection ○ ….
- 43. Different CPU Profilers ● Instrumenting ○ Adds timing code to application ● Sampling ○ Collect thread dumps periodically ○ VisualVM, JProfiler, Yourkit, ….
- 44. Sampling CPU Profilers [survey made by RebelLabs]
- 45. Sampling Profilers Samples MainThread.run() Backend.findUser() Controller.doAction() new User() fetchUser() display() someLogic() moreLogic() evenMoreLogic()
- 46. Sampling Profilers More samples MainThread.run() Backend.findUser() Controller.doAction() new User() fetchUser() display() someLogic() moreLogic() evenMoreLogic()
- 47. Sampling Profilers Stack tracing ● Most profilers use JVMTI ○ Using GetCallTrace ■ Triggers a global safepoint ■ Collect stack trace ● Large impact on application ● Samples only at safepoints
- 48. What is a safepoint? Java threads poll a global flag ○ At method exit/enter ○ At “uncounted” (int) loops
- 49. What is a safepoint? A safepoint can be delayed by ○ Large Methods ○ Long running “uncounted” (int) loops
- 50. Sampling Profilers Safepoint bias MainThread.run() Backend.findUser() Controller.doAction() new User() fetchUser() display() someLogic() moreLogic() evenMoreLogic()
- 51. Safepoint summary JVM have many safepoint operations • To monitor its impact use – -XX:+PrintGCApplicationStoppedTime – -XX:+PrintSafepointStatistics – -XX:+PrintSafepointStatisticsCount=X
- 52. Sample Profilers Java profilers that work better! ● Profilers that use AsyncGetCallTrace ○ Java Mission Control ■ Very good tool, just don’t use it in production (without a license) ○ Oracle Solaris Studio ■ Not well known, it’s free and it works on Linux ○ Honest Profiler ■ Open source, cruder, but works very well
- 53. Java Mission Control/Flight Recorder ● Designed for usage in production systems ● Potentially low overhead ○ Be wary of what you record ■ Capture everything is not a good strategy ■ Capture data for one specific thing (memory, contention, cpu) ● Capturing data will not be skewed by safepoints ○ Make sure to use: ■ -XX:+UnlockDiagnosticVMOptions -XX:+DebugNonSafepoints ● Need a license to be used in production, free to use for development
- 54. Java Profilers problem ● Java stack only ● Method tracing have large observer effect ● Do not report: ○ GC ○ Deopt ○ Eg System.arrayCopy ….
- 56. Perf ● A system profiler ● Show the whole stack ○ JVM ○ GC ○ Kernel ● Previously not very useful for Java ○ Missing stacks ○ Method symbols missing
- 57. Perf ● Solution ○ Java8u60 added the option -XX:PreserveFramePointer ■ Allows system profilers to capture stack traces ● Visibility of everything ○ Java methods ○ JVM, GC, libraries, kernel ● Low overhead ● Flamegraph
- 58. System C++ Java
- 59. Flamegraph Top edge show which method is using CPU and how much. MainThread.run() a() b() e() c() d()
- 61. Limitations of Perf Mixed Mode ● Frames might be missing (inlined) ● Disable inlining: ○ -XX:-Inline ○ Many more Java frames ○ Will be slower ● perf-map-agent have experimental un-inline support
- 62. Profiling at Red Hat ● Perf for CPU profiling ● Java Mission Control ○ Contention ○ Thread analysis ○ Memory usage
- 63. Benchmarking
- 64. Benchmarking Most benchmarks are flawed, wrong and full of errors.
- 65. Benchmarking Most benchmarks are flawed, wrong and full of errors ○ Used cautiously it can be a very valuable tool to reveal performance issues, compare applications, libraries, ...
- 66. Benchmarking ● Java Benchmarking libraries ○ Microbenchmarks ■ Java Microbenchmark Harness ● http://openjdk.java.net/projects/code-tools/jmh/ ■ JMH is the only library on Java we recommend for microbenchmarks ■ Still possible to write bad benchmarks with JMH
- 67. Benchmarking Load testing frameworks ○ Gatling ■ http://gatling.io/ ○ Faban ■ http://faban.org/
- 68. Benchmarking A Hibernate microbenchmark lesson ● We wanted to compare cache lookup performance between Hibernate 4 and 5 ○ We also wanted to test a new cache we added to Infinispan, Simple cache ● Created several JMH benchmarks that tested different use cases ○ Default cache with and without eviction ○ Simple cache with and without eviction
- 69. Benchmarking A Hibernate microbenchmark lesson 4.3 w/ eviction 292050 ops/s 4.3 w/o eviction 303992 ops/s 5.0 w/ eviction 314629 ops/s 5.0 w/o eviction 611487 ops/s 5.0 w/o eviction (simple cache) 706509 ops/s
- 70. Benchmarking We progressed to a large full scale EE benchmark. ● We expect similar or better results vs EAP6 (Hibernate 4.2)
- 71. Benchmarking We progressed to a large full scale EE benchmark. ● We expect similar or better results vs EAP6 (Hibernate 4.2) ○ The response times are 5-10x slower! ○ And we are now CPU bound
- 72. Benchmarking We progressed to a large full scale EE benchmark. ● We expect similar or better results vs EAP 6 (Hibernate 4.2) ○ The response times are 5-10x slower! ○ And we are now CPU bound ● How is that possible?
- 73. Benchmarking We progressed to a large full scale EE benchmark. ● We expect similar or better results vs EAP 6 (Hibernate 4.2) ○ The response times are 5-10x slower! ○ And we are now CPU bound ● How is that possible? ○ We had several microbenchmarks showing better performance on Hibernate 5 ○ Could the problem lie in WildFly 10? ○ Let’s profile!
- 74. Benchmarking
- 75. Benchmarking
- 76. Benchmarking What had happened? ● Why did we spend so much CPU in this method and why do it not reflect the results from the microbenchmarks?
- 77. Benchmarking What had happened? ● Why did we spend so much CPU in this method and why do it not reflect the results from the microbenchmarks? ○ We started debugging ■ -XX+PrintCompilation ● Show when/which methods are compiled/decompiled ● Showed that the method only was compiled once, but twice on EAP 6 (Hib4.2) ● Why?
- 78. Benchmarking What had happened? ● We had made several changes internally in Hibernate 5 to reduce memory usage
- 79. Benchmarking What had happened? ● We had made several changes internally in Hibernate 5 to reduce memory usage ○ One specific class was refactored to an interface ○ Changing a monomorphic call site to a bimorphic call site ■ Which can prevent compiling/inlining of methods!
- 80. Benchmarking What had happened? ● We had made several changes internally in Hibernate 5 to reduce memory usage ○ One specific class was refactored to an interface ○ Changing a monomorphic call site to a bimorphic call site ■ Which can prevent compiling/inlining of methods! ● Direct method calls will “always” be optimized (no subclassing) ● In Java subclassing/inheritance might cause the JVM to no optimize method calls
- 81. Benchmarking Lessons learned ● Code changes might have unexpected consequences ○ In this case, reduced memory, increased CPU usage ● Benchmarks are good, but should always be questioned ○ When you benchmark, analyze (all/most) possible use cases
- 82. Benchmarking Lessons learned ● Code changes might have unexpected consequences ○ In this case, reduced memory, increased CPU usage ● Benchmarks are good, but should always be questioned ○ When you benchmark, analyze (all/most) possible use cases ● Yes, we ended up fixing the CPU usage without causing it to use more memory!
- 83. EAP 7 Performance Improvements Performance highlights ● JPA ● JCA ● Web
- 84. EAP 7 Performance Improvements Hibernate 5 performance improvements ● Memory usage ○ Reduced memory usage 20-50%
- 85. EAP 7 Performance Improvements Hibernate 5 performance improvements ● Memory usage ○ Reduced memory usage 20-50% ● Cache improvements ○ Simple Cache ■ 132% Improvement with immutable objects
- 86. EAP 7 Performance Improvements Hibernate 5 performance improvements ● Memory usage ○ Reduced memory usage 20-50% ● Cache improvements ○ Simple Cache ■ 132% Improvement with immutable objects ● Pooled Optimizer ○ In persistence.xml add property ■ hibernate.id.optimizer.pooled.preferred value="pooled-lotl”
- 87. EAP 7 Performance Improvements Hibernate 5 performance improvements ● Bytecode enhancements ○ hibernate.enhancer.enableDirtyTracking ○ hibernate.enhancer.enableLazyInitialization ● Improved caching ○ hibernate.cache.use_reference_entries ○ hibernate.cache.infinispan.immutable-entity.cfg = “immutable-entity”
- 88. EAP 7 Performance Improvements IronJacamar performance improvements ● Contention issues ○ New default ManagedConnectionPool
- 89. EAP 7 Performance Improvements IronJacamar performance improvements ● Contention issues ○ New default ManagedConnectionPool ● Disabled logging ○ Not everything is disabled ■ <datasource …. enlistment-trace="false" >
- 90. EAP 7 Performance Improvements IronJacamar performance improvements ● Contention issues ○ New default ManagedConnectionPool ● Disabled logging ○ Not everything is disabled ■ <datasource …. enlistment-trace="false" > ● Fairness ○ Set to true at default ■ <datasource> <pool><fair>false</fair></pool>
- 91. EAP 7 Performance Improvements Undertow vs JBossWeb ● Undertow is nonblocking ● JBossWeb have a thread for each connection
- 92. EAP 7 Performance Improvements Simple HelloServlet Benchmark EAP 6.4 EAP 7 RPS Mean 95% 99% Mean 95% 99% 5000 2 1 4 0 1 1 15000 3 4 56 1 2 6 25000 13 18 247 1 3 7 40000 46 246 414 12 23 84 55000 361 647 1889 65 136 635
- 93. EAP 7 Performance Improvements ● Lightweight ● Embeddable ● Scalable ● HTTP/2 ● HTTP Upgrade
- 94. EAP 7 Performance Improvements Overall EAP 7 Performance tricks ● Remote byte pooling ○ jboss.remoting.pooled-buffers ● Disable CDI ○ CDI is enabled by default in EAP 7
- 95. EAP 7 Performance Improvements Overall EAP 7 Performance tricks ● Remote byte pooling ○ jboss.remoting.pooled-buffers ● Disable CDI ○ CDI is enabled by default in EAP 7
- 96. Q&A