Javonet性能疑问：千万次循环调用.NET DLL方法的效率问题

Great question—this is exactly the kind of edge case where interop tooling can trip you up if you don’t optimize properly. Let’s break this down:

First, your hunch is right: if you’re passing the method name as a string every single time in the loop, Javonet will indeed incur reflection overhead to resolve that method each iteration. For 10 million calls, that’s going to add up fast—reflection isn’t free, and repeated lookups will absolutely drag down performance.

But the good news is there’s a straightforward fix: cache the method reference upfront instead of resolving it in the loop. Here’s how that looks in practice (using Java as an example, but the pattern applies to all Javonet-supported languages):

// Initialize Javonet and load your DLL once (outside the loop)
Javonet.activate("your-license-key");
var dotnetRuntime = Javonet.inMemory().netcore();
var myLibrary = dotnetRuntime.loadLibrary("YourBusinessDLL.dll");
var targetClass = myLibrary.getType("YourNamespace.YourClass").createInstance();

// Resolve the method ONCE, before the loop
var cachedMethod = targetClass.getMethod("YourMethodName");

// Now run your 10M loop using the cached reference
for (long i = 0; i < 10_000_000; i++) {
    cachedMethod.invoke(yourParametersHere);
}

By calling getMethod just once, you skip the reflection lookup entirely in the loop. Javonet will reuse the resolved method handle for every invocation, which brings the performance much closer to direct .NET method calls.

If you want to squeeze even more performance out, consider batching your calls. Instead of making 10M individual cross-language calls, create a helper method in your .NET DLL that processes a batch of inputs (say, 1000 at a time). Then you only need to call into Javonet 10,000 times instead of 10 million—this cuts down on the fixed overhead of crossing the language boundary, which is often a bigger bottleneck than reflection itself.

One last thing: while some interop tools do have implicit caching for resolved methods, never rely on that for high-throughput scenarios. Explicitly caching the method reference gives you full control and guarantees you’re not paying unnecessary lookup costs.

内容的提问来源于stack exchange，提问作者Jonathan Sylvester