hi , this is a benchmark Between Java and Rust : Rust result : 10648, 6678, 8274 Java result : 8661, 9608, 6302 avg of 12 times benchmark Rust : 9948 Java : 8693 I used opt-level = 3 for Rust Rust Code fn main() { for _ in 0..3 { let now = std::time::Instant::now(); //…

Mostly because the Rust code does more works. What they're doing underneath are: Rust Repeat step 2 ~ 8 3 times. Record the current time. Allocate heap memory of 100 * 56 bytes. Repeat step 5 100 times. Allocate two heap memories of 5 bytes and fill them with fixed value "frame". The iterate-and-v…

My immediate guess is that its because the Rust code will spend time allocating space for, and copying string data into the fields, whereas the Java code just stores a String object that already exists before the loop starts running.

then JVM is not slower than LLVM and sometimes faster at least for something like allocation and processing over data ( my means not math) or maybe can write faster code without maximize hard coding and advance optimization in Rust is it correct ?

I mean, in this particular case, the code is simply not doing the same thing, and Java happens to be doing less work. That said, it is true that there are cases where the JVM will be faster. In particular, the JVM tends to be faster at making a large number of small heap allocations.

[image] DanyalMh: pub fn new(fname: &str, lname: &str, age: i32) -> Self { Class { fname: fname.to_string(), lname: lname.to_string(), ^ This is copying the strings. [image] DanyalMh: for (int i = 0; i < 100 ; i++) { arr.a…

In your case, the issue has to do with Java having garbage collection and copying references. In Rust, you need to be clear whether your structures want to own or borrow the elements. In your case, the structure contains an owned version of str which means having spending time to copy the contents …

[image] Hyeonu: The critical part is that allocating on GC heap is really cheap. If most of your task is to allocate memory, using GC language would be more performant. thanks for your answer , then why in some java software use off-heap to avoid GC heap ?? ok it make Garbage but increase p…

ZGC creates a very short pause of less than 10 milliseconds, Do you think it is good to choose ZGC now for Big software instead of off-heap? Because it does not wait for the Garbage to be big and become expensive

It depends, on performance you should only trust benchmarks. But note that the pause time is not the only perf stat the GC have. Nowadays it spends a lot more time in parallel. CPU is a shared resource, using more of it in GC thread would reduce the process' throughput. Also, 10ms is not instant - y…

[image] DanyalMh: ZGC creates a very short pause of less than 10 milliseconds, 10 milliseconds is pretty darn long considering that 1. today's computers have clock cycles and instructions that work at the nanosecond scale, and 2. 10 milliseconds is already too slow if you need e.g. real-time …

Why Java program is faster than Rust in this comparision?

Hyeonu February 16, 2022, 10:29am 10

Because they not only allocate memories but also free them. Running GC over large amount of objects is an expensive task.

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Why Java program is faster than Rust in this comparision?

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