[tom_mellior]

> It was always a dumb choice to make member functions default to virtual semantics, when they almost always don't need it, and it just costs performance to no purpose.

If you actually don't need it (i. e., your hot methods are never overridden), then the JIT will trivially compile those "virtual" method calls as non-virtual ones. It has all the information it needs, since it knows what classes are loaded. It can invalidate its code if necessary, if you load more classes that do add overrides. So no, it does not cost performance at the call site. It does cause the compiler to do work, but nothing fancy.

[blakehaswell]

> If you actually don't need it (i. e., your hot methods are never overridden), then the JIT will trivially compile those "virtual" method calls as non-virtual ones.

But isn't that the thrust of this article? Of course the JIT can optimise a monomorphic call-site. The question is, in reality, what percentage of the time will it be optimised for your users?

[kaba0]

You can even aot compile a class and have the cached “JIT compiled” code loaded on startup.

https://docs.oracle.com/en/java/javase/13/docs/specs/man/jao...

[tom_mellior]

What the article doesn't acknowledge is that there are many ways to force compilation of your code. You can change the threshold for the number of executions before the JIT is called. You can run scripts as part of your deployment that exercise the paths you are interested in. So yes, it's true that "this code runs very infrequently, but I still care about its latency" is not what JVMs might be optimized towards. But it's possible to understand the issues and solve them.

[ncmncm]

To need to understand and solve issues is always worse than not to need either.

Java got commercial success despite its many design flaws, not because of them. $1B+ promotion from Sun helped some, providing a route to freedom from Microsoft sharecropping helped more.

[pjmlp]

And from being way better than either C or C++ to write distributed applications.

Having done that with C across the major UNIX flavours around 2000 and later again with C++ and CORBA a couple of years later, it is kind of obvious why most enterprises moved into it (and its nemesis, .NET).