title: Why wouldn't the JIT compile the whole program over time?
body: <p>Consider a JIT programming language like Java or C#.
  It is known the VM (e.g. the JVM) uses some metrics to decide which code parts need a speed-up and it compiles it to machine code.</p>
  <p>My question is, if we consider a long running process like an HTTP server, wouldn't it be better to compile the whole process over time? Are there any downsides to JIT compiling?</p>