Hacker News Reader

Comment by josefx | Hacker News Reader

> And as an aside to the aside: Check out this race condition that Wouter Coekaerts found in the String(char[]) constructor as a result of this optimization.

Quite sure neither the char array nor the String constructor pretend to be thread safe and messing with the input of a constructor in parallel would break most java code in existence in weird and unexpected ways.

View on HN

The linked problem goes far past the result object being unstable though - namely, with it you can affect any string in any class file that the JVM loads in the future. That is, you can get yourself into a situation where the following function returns false:

    boolean foo() {
      System.out.println("hello world".startsWith("hello"));
    }

Yeah, I'd expect that almost any code would react badly to modifying a ctor argument in parallel. That seems like a very bad thing to do in general.

Reply on news.ycombinator.com