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Showing posts from December, 2015

Why I don't like System.gc()

I wrote this for internal-to-my-company consumption, but I couldn't find a reasonable place to put it. And then I remembered I had a blog. The question to me was whether is ever made sense to do a System.gc() , and, more specifically, whether it made sense to do System.gc() followed by System.runFinalization() . I can't claim it is always wrong. It suffers from what some people call the Politician's syllogism : Something must be done, this is something, therefore we must do it. There's no control over GC other than a big red button labeled "System.gc()", so this is always the something that must be done. In practice, the biggest problem with System.gc() is that what it does is rather unpredictable. In fact, there's no guarantee that it will do anything. In fact, Hotspot has a -XX:DisableExplicitGC flag to stop it from doing anything. So, it can sometimes solve an immediate problem in a system-dependent way, but you are introducing a signi