The myth of dynamic language performance

Talk at DevConTLV about how to make your dynamic language implementation faster. What are some basic techniques used and how do they work.

Transcript

1. The myth of dynamic
   language performance
   DevConTLV
   

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2. Dirkjan Bussink
   @dbussink
   

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3. Rubinius
   A Ruby implementation
   

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5. “PHP too slow for Facebook,
   builds its own faster version”
   “Everything you heard about Ruby being slow
   is not true. It’s about twice as slow as that”
   “How JavaScript is Slowing Down the Web”
   2006
   

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9. Static vs. Dynamic
   

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10. Weak vs. Strong
    

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11. C PHP
    Java Ruby
    Static Dynamic
    Weak
    Strong
    

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13. The lure of the hash table
    

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14. class MethodTable
    def initialize
    @methods = {}
    end
    def store_method(name, code)
    @methods[name] = code
    end
    def find_method(name)
    @methods[name]
    end
    end
    

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15. class Address {
    private String street;
    private Integer number;
    private String city;
    public Address(String street, Integer number, String city) {
    this.street = street;
    this.number = number;
    this.city = city;
    }
    }
    

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16. class Address {
    private HashTable instance_variables;
    public Address(String street, Integer number, String city) {
    instance_variables = new HashTable();
    instance_variables.put("street", street);
    instance_variables.put("number", number);
    instance_variables.put("city", city);
    }
    }
    

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17. Hash tables everywhere!
    

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18. Inline caching
    

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19. p = Person.new
    p.name
    
    

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20. Specific object layout
    

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21. class Address
    attr_reader :street
    attr_reader :number
    attr_reader :city
    end
    Address.instance_variable_get("@seen_ivars")
    => [:@street, :@number, :@city]
    

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22. 0001: push_ivar :@number
    self[1]
    Removes hash
    table lookup
    

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23. Just in time compilation
    

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24. def method1
    1 + method2
    end
    def method2
    2 + 1
    end
    100000.times do
    method1
    end
    ...
    0x110ed90e7 mov $0x9, %eax
    0x110ed90ec jmp 0x119 ; 0x110ed9129
    ...
    0x110ed9129 addq $0xa0, %rsp
    0x110ed9130 pop %rbp
    0x110ed9131 ret
    1 + 2 + 1 = 4
    FIXNUM(4) = 0x9
    

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25. What about you
    as a developer?
    

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26. Be nice
    

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27. Write type stable code
    

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28. Small and simple methods
    

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29. Benchmark!
    

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30. Recap
    

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31. Fast dynamic languages
    are harder, not impossible
    

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32. Writing simple and well
    factored code is often
    easy to optimize for a VM
    

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33. ?
    

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