Is your profiler speaking the same language as you? -- Docklands JUG
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The document discusses various performance tools and techniques for Java applications, focusing on profiling and monitoring methods such as sampling and tracing. It highlights the importance of understanding performance bottlenecks and emphasizes questions developers should ask to identify areas for improvement. Additionally, it mentions specific tools like XRebel and JRebel for enhancing performance analysis.
Is your profiler speaking the same language as you? -- Docklands JUG
- 1. Is your profiler speaking the same language as you? Simon Maple @sjmaple
- 3. Agenda • Performance Tools • Performance by numbers • Sampling vs Tracing • XRebel • JRebel 3
- 5. Performance Tools • Java Monitoring Tools • Java Profilers • Java Testing Tools 5
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- 16. The Journey of Performance 16
- 20. Profiling CPU Tracing Sampling Memory Usage Allocation We are only talking about this part today
- 21. JVM has ability to produce thread dump: Press Ctrl+Break on Windows kill -3 PID on *nix "http-nio-8080-exec-1"#40 daemon prio=5 os_prio=31 tid=0x00007fd7057ed800 nid=0x7313 runnable java.lang.Thread.State: RUNNABLE at o.s.s.p.w.OwnerController.processFindForm(OwnerController.java:89) at s.r.NativeMethodAccessorImpl.invoke0(Native Method) at s.r.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62) at s.r.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43) at j.l.r.Method.invoke(Method.java:497) What is a sample?
- 22. Sampling interval : 20 ms Sample count: 4
- 23. Sampling interval : 1 ms Sample count: 100+
- 27. Taming safepoint bias Java Mission Control Proprietary protocol Java 7u40 Honest Profiler https://github.com/RichardWarburton/honest-profiler AsyncGetCallTrace JVMTI NB! not documented
- 28. public void businessMethod() { long start = System.currentTimeMillis(); work(); Profiler.log(System.currentTimeMillis()-‐start); } Tracing (Instrumentation)
- 29. Tracing public void businessMethod() { long start = System.nanoTime(); work(); Profiler.log(System.nanoTime()-‐start); }
- 30. Tracing public void businessMethod() { Profiler.start(“businessMethod"); try { work(); } finally { Profiler.log("businessMethod"); } }
- 31. System.nanoTime System.currentTimeMillis Parallel thread updating easily accessible memory location sleep-wakeup-update yield-wakeup-update busy-loop-update
- 32. class Profiler { Loop loop; public static void start(String method) { long now = loop.getTime(); … }
- 33. public class Loop implements Runnable { private volatile long time; public void run() { while (running) { time = System.nanoTime(); sleep(); } } public final long getTime() { return time; } Busy Loop
- 34. Nano seconds put into perspective Reading memory is not free. It takes cycles = nanoseconds Each (software) layer is not free. JVM,JNI,OS,HW http://shipilev.net/blog/2014/nanotrusting-nanotime/ Nanotrusting the NanoTime
- 35. Nano seconds put into perspective http://shipilev.net/blog/2014/nanotrusting-nanotime/ Nanotrusting the NanoTime granularity_nanotime: 26.300 +-0.205 ns latency_nanotime: 25.542 +-0.024 ns granularity_nanotime: 29.322 +-1.293 ns latency_nanotime: 29.910 +-1.626 ns granularity_nanotime: 371,419 +-1,541 ns latency_nanotime: 14,415 +-0,389 ns Linux Solaris Windows
- 36. Sleep timer: time-slicing & scheduling Minimum sleep times: Win8: 1.7 ms (1.0 ms using JNI + socket poll) Linux: 0.1 ms OS X: 0.05 ms VirtualBox + Linux: don’t ask :) Still uses 25-50% of CPU core Yield? Windows scheduler skips yielded threads in case of CPU starvation
- 37. public class Loop implements Runnable { private volatile long time; public void run() { while (running) { time = System.nanoTime(); sleep(); } } private void sleep() { if (!MiscUtil.isWindows()) { Thread.yield(); } } Busy Loop
- 38. public class Loop implements Runnable { private volatile long time; public void run() { while (running) { time = System.nanoTime(); sleep(); } } private void sleep() { if (!MiscUtil.isWindows()) { Thread.yield(); } } Busy Loop
- 39. Busy Loop public class Loop implements Runnable { private volatile long time; public void run() { while (running) { time = System.nanoTime(); sleep(); } } private void sleep() { if (!MiscUtil.isWindows()) { Thread.yield(); } }
- 40. public class Loop implements Runnable { private volatile long time; public void run() { while (running) { time = System.nanoTime(); sleep(); } } private void sleep() { if (!MiscUtil.isWindows()) { Thread.yield(); } } Busy Loop
- 41. main() foo() bar() baz() Tracing relatively higher overhead for fast methods :(
- 42. Database access Web Services RMI Various application layers 3rd-party components HTTP session Exceptions Caches File system access View rendering Serialization GC What other performance considerations should we have?
- 43. Questions you should be asking …….. …….. …….. ……..
- 44. Questions you should be asking Where was most of the time spent? How many SQL queries were executed? How much time did the external calls take? What’s my HTTP session state? Is caching working properly? Is there any excessive work done by the app?
- 45. Most improvement gained here! This is where we should focus first! A B C D E
- 47. Download trials and get FREE shirts :) JRebel: http://0t.ee/docklandsjr XRebel: http://0t.ee/docklandsxr 47