Just-in-time (JIT) compilation is a technique used in computer programming to improve the performance of runtime execution. It involves dynamically compiling code at runtime instead of compiling it ahead of time and storing it in binary form.
When a program is executed, the JIT compiler analyzes the code and identifies frequently executed parts of the code. It then compiles those parts into machine code and stores the compiled code in memory, making it available for reuse during subsequent executions of the program. This process allows the program to execute faster because the compiled code is optimized for the specific hardware and operating system on which it is running.
JIT compilation is commonly used in interpreted languages like Java, Python, and .NET, where the code is executed by a virtual machine. When the virtual machine encounters a frequently executed section of code, it calls the JIT compiler to compile the code into machine code, improving the performance of the program.
One advantage of JIT compilation is that it allows for more flexibility in the code. The compiled code can be optimized for the specific hardware and operating system on which it is running, improving performance. Additionally, JIT compilation can help reduce memory usage by only compiling the code that is needed at runtime.
However, JIT compilation can also introduce overhead during runtime, as the compiler needs to analyze and compile the code on the fly. Furthermore, the compiled code is stored in memory, which can consume significant amounts of resources, especially for large programs. Despite these potential drawbacks, JIT compilation is a useful technique for improving performance in many software applications.