This can be reliably reproduced (or not reproduced, depending on what you want) with openjdk version “1.8.0_222” (used in my analysis), OpenJDK 12.0.1 (according to Oleksandr Pyrohov) and OpenJDK 13 (according to Carlos Heuberger). I ran the code with -XX:+PrintCompilation enough times to get both behaviours and here are the differences. Buggy implementation (displays output): … Read more
There’s a good discussion at Lambda the Ultimate. LuaJIT is very good. Many people have reported impressive speedups on lua-l (the lua mailing list). The speedups are most impressive for pure Lua code; the trace compiler is not as effective when there are lots of calls to C functions in loadable library modules.
A JIT compiler can be faster because the machine code is being generated on the exact machine that it will also execute on. This means that the JIT has the best possible information available to it to emit optimized code. If you pre-compile bytecode into machine code, the compiler cannot optimize for the target machine(s), … Read more
Torch Script is one of two modes of using the PyTorch just in time compiler, the other being tracing. The benefits are explained in the linked documentation: Torch Script is a way to create serializable and optimizable models from PyTorch code. Any code written in Torch Script can be saved from your Python process and … Read more
You compile your code to IL which gets executed and compiled to machine code during runtime, this is what’s called JIT. Edit, to flesh out the answer some more (still overly simplified): When you compile your C# code in visual studio it gets turned into IL that the CLR understands, the IL is the same … Read more
There is no performance gain in moving the constant into the class. The CLR is smart enough to recognize constants as constant, so as far as performance goes the two are equal. What actually happens when you compile to IL is that the values of the constants are hardcoded into the program by the compiler … Read more
In general, Just-in-time compilation refers to compiling native code at runtime and executing it instead of (or in addition to) interpreting. Some VMs, such as Google V8, don’t even have an interpreter; they JIT compile every function that gets executed (with varying degrees of optimization). On Stack Replacement (OSR) is a technique for switching between … Read more
Why is Java faster than Python on this example loops? Novice Explanation: Think of a program like a freight train that lays its own train-track as it moves forward. Track must be laid before the train can move. The Java Freight train can send thousands of track-layers ahead of the train, all working in parallel … Read more
Why is LLVM Unsuitable for building a JIT? I wrote HLVM, a high-level virtual machine with a rich static type system including value types, tail call elimination, generic printing, C FFI and POSIX threads with support for both static and JIT compilation. In particular, HLVM offers incredible performance for a high-level VM. I even implemented … Read more
wow, this turned out to be a lot more painful than I expected. 100% of the pain was linux protecting the program from being overwritten and/or executing data. Two solutions shown below. And a lot of googling was involved so the somewhat simple put some instruction bytes and execute them was mine, the mprotect and … Read more