Actually this is not true. Hotspot can deoptimize code. It optimizes making some assumptions. If these assumptions stop holding, code gets deoptimized, measu

Actually this is not true. Hotspot can deoptimize code. It optimizes making some assumptions. If these assumptions stop holding, code gets deoptimized, measured for a while, and reoptimized with new assumptions. For example, an interface implemented by only 1 class might get the class inlined. If a second implementer pops up (which can happen at runtime for e.g. some dynamically generated class), all of this will get undone. There was a series of small articles with all these things, but I can't seem to find them right now.