Great ways to improve java performance
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This document discusses the importance of Java performance and provides eight puzzles with morals about improving Java performance. Specifically, it notes that performance should be planned initially, provides puzzles about avoiding object creation with new, using primitive types over strings, precomputing string lengths, method inlining, reusing objects like arrays and BufferedReaders, and reusing existing Java libraries. The puzzles are intended to teach ways to improve performance through practices like these.
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Great ways to improve java performance
- 2. Why performance is so important? Java 2 www.sainivas.com
- 3. Imagine a world where everything is UNLIMITED 3 www.sainivas.com
- 4. Sorry!!You are in a world where everything is LIMITED 4 www.sainivas.com
- 5. Why performance matters? 90% of requirements are complex 50% of apps share the same server 10% increase in end users every day Performance should be planned initially and not inspected later. 5 www.sainivas.com
- 6. Great ways to improveJava Performance By B. Sai Prasad 6 www.sainivas.com Simple
- 7. Introduction Java Puzzles Short program Where is the issue? How to fix? What did you learn? 7 www.sainivas.com
- 8. Puzzle #1 8 www.sainivas.com
- 9. Moral #1new operator creates a new object “new operator can be avoided by re-using byte arrays, or re-using objects” 9 www.sainivas.com
- 10. Puzzle #2 10 www.sainivas.com
- 11. Moral #2Creating a Double from a string takes about 15 times than from a number “Use primitive data types for constructors rather than String objects.” 11 www.sainivas.com
- 12. Puzzle #3 12 www.sainivas.com
- 13. Moral #3length() call in a tight loop can hit performance “String length is pre-computed, stored in a local variable and used it in a tight loop” 13 www.sainivas.com
- 14. Puzzle #4 14 www.sainivas.com
- 15. Moral #4Default constructor is added automatically by compiler. “Generated constructor invokes the super class constructor.” 15 www.sainivas.com
- 16. Puzzle #5 16 www.sainivas.com
- 17. Moral #5Minimize method calls by method inlining “Inlining is done by expanding the inlined method’s code in the code that calls the method” 17 www.sainivas.com
- 18. Puzzle #6 18 www.sainivas.com
- 19. Moral #6System.arraycopy()efficiently copies one array to another “For very short arrays, use of this method may be counterproductive, because of overhead in actually calling the method” 19 www.sainivas.com
- 20. Puzzle #7 20 www.sainivas.com
- 21. Moral #7BufferedReader reads characters in chunks “the read() method found in BufferedReader simply returns characters from a buffer” 21 www.sainivas.com
- 22. Puzzle #8 22 www.sainivas.com
- 23. Moral #8Reuse. Reuse. Reuse. “It is better to reuse the java libraries than creating something new” 23 www.sainivas.com