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The investment in optimization in CLR or JVM can be huge as they impact millions of applications. While each C / C++ code will have to be hand optimized. Also
by blackoil 3y ago
The investment in optimization in CLR or JVM can be huge as they impact millions of applications. While each C / C++ code will have to be hand optimized.
Also limits on number of people in given time who can write optimal C code vs C# will also make managed code better.
- rfoo 3y agoPlus that it's easier to have unmanaged code in C# than in Java.
- larodi 3y agoIs it possible to have unmanaged code in Java at all… or you mean linking libs and exposing them through Java API in the lang?
- rfoo 3y agoAh, I meant Java code manipulating off-heap memory. For Java I don't think there's a way to mix managed and unmanaged code like you do in C#/C++ CLR.
- neonsunset 3y agoIn C# you usually don't want to mix in C++. Manipulating off-heap memory is indeed easy - nowadays pointers to both object interiors, stack and unmanaged memory can be represented as `ref T` where T is byte, int, etc. These are then subsequently wrapped by `Span<T>` and `ReadOnlySpan<T>` respectively. This way a span can be a slice of memory that can have any origin: var fromStack1 = (stackalloc byte[32]); var fromStack2 = (Span<byte>)[0x20, 0x20, 0x20, 0x20]; var fromHeap = new byte[32].AsSpan(); unsafe { var ptr = NativeMemory.Alloc(32); var fromMalloc = new Span<byte>(ptr, 32); // Don't forget to free :) }
- pjmlp 3y agoPanama has helped into that direction, it isn't like C# though, for feature parity we will eventually need Valhalla, which since they want to keep existing JARs working, it is taking its time. Ignoring the type systems from Eiffel, Objective-C, Oberon and Modula-3 linage, even though they were inspirations for Java, has been shown to have been a bad decision in hindsight.
- pjmlp 3y agoTrue, I still look forward to have Valhala, eventually.
- theLiminator 3y agoCouldn't you just replace the CLR and JVM with llvm and gcc and then replace C with assembly and arrive at the same conclusion.
- Dumble 3y agoI'm not the person you are replying too, but I believe that of course, the pattern holds if you keep shifting it down. I.E. using a faster CPU will speed up all programs running on it, each (already optimized) ASIC has to be optimized further individually.
- blackoil 3y agoNow commenting beyond my expertise, I understand both ecosystems have developed orthogonally, C#/Java assumes code to be higher level and "dumb" and optimization are in library/CLR/JVM. While C/C++ are developed with code at lower level and developer making sure code is optimized. Now, I could be talking out of ass, haven't done enough C/C++ coding in over a decade.
- balls187 3y agoYou can write poorly optimized C#. And the intel C++ compiler has provided significant performance for decades via optimization without needing to optimize by hand.
- astral303 3y agoI don’t think so, because it is the runtime JIT (Just-In-Time) optimizer that is the critical speed advantage that allows the CLR and JVM to beat C and C++. The inlining of virtual calls is the critical optimization that enables this. Because C/C++ is optimized statically and never at runtime, it is unable to optimize results of function pointer lookups (in C, and thus also virtual calls in C++). However, the JITs can inline through function pointer lookups. In sufficiently complex programs, where polymorphism is used (i.e. old code that calls new code without knowing about it), this yields an unsurpassed speed advantage. Polymorphism is critical to managing complexity as an application evolves (even the Linux kernel, written in C, uses polymorphism, e.g. see struct file_operations).