Appendix B. Performance tooling and empirical performance analysis 181
========== ===== ====== ====== ======= =====
.jitMonitorEntry 1121 26.66 nathelp.s 549fc0 cc0
Garbage Collection impact: The impact of initializing new objects and of GC is shown in
Example B-13 on page 180 as the 12.13% of ticks in the libj9gc24.so shared object. This
high GC impact is related to the excessive creation of Double objects in the sample
program.
Java method execution: In Example B-14, the profile shows the time that is spent in the
ProfileTest class, which is broken down by method. Some methods appear more than
one time in the breakdown because they are compiled multiple times at increasing
optimization levels by the JIT compiler. Most of the ticks appear in the final highly
optimized version of the doWork()D method, into which the initialize()V and
calculate()V methods are inlined by the JIT compiler.
Example B-14 AIX profile excerpt showing Java classes and methods
Total Ticks For All Processes (JAVA) = 1450
Class Ticks %
===== ===== ======
ProfileTest 1401 33.32
java/util/Random 38 0.90
java/lang/Float 5 0.12
java/lang/Double 3 0.07
java/lang/Math 3 0.07
Profile: ProfileTest
Total Ticks For All Processes (ProfileTest) = 1401
Method Ticks % Source Address Bytes
====== ===== ====== ====== ======= =====
doWork()D 1385 32.94 ProfileTest.java 1107283bc b54
doWork()D 6 0.14 ProfileTest.java 110725148 464
doWork()D 4 0.10 ProfileTest.java 110726e3c 156c
initialize()V 3 0.07 ProfileTest.java 1107262dc b4c
calculate()V 2 0.05 ProfileTest.java 110724400 144
initialize()V 1 0.02 ProfileTest.java 1107255c4 d04
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