Interpreter in Swift fails with `EXC_BAD_ACCESS` at `Interpreter.copy(data, toInputAt: 0)` and `Interpreter.input(at: 0)` in some circumstances
I have an update on this issue. When I use the `init(modelPath:delegates:)` initialiser it works. The `EXC_BAD_ACCESS` crash only happens when I use the `init(modelData:delegates:)` initialiser. Hi @jakubdolejs, it looks like you're both loading the model and running inference on it asynchronously. Is it possible that they are somehow running out of order then? i.e. inference ends up running before the model is actually loaded. Do you need to load it asynchronously? I'm guessing you are calling init before run inference somewhere, perhaps change init to load it synchronously that way it has to initialize before you run inference on it. Hi @pkgoogle,

Thanks for getting back to me. The queue is serial and it can't execute the two statements concurrently. The interpreter is created (asynchronously) in the class initialiser. The `runInference` method also dispatches the inference task on the same queue on which the interpreter was created. Since the queue is serial it can only execute one task at a time and the interpreter creation comes first.

The weird thing is the same task succeeds when I use the `init(modelPath:delegates:)` interpreter initialiser but it fails when I use the `init(modelData:delegates:)` one. Hi @jakubdolejs, that's true, do you happen to have the code around where you create an Inference object and call runInference on it? Generally the more code/information you share, the easier it will be for us. This issue is stale because it has been open for 7 days with no activity. It will be closed if no further activity occurs. Thank you. This issue was closed because it has been inactive for 7 days since being marked as stale. Please reopen if you'd like to work on this further. Are you satisfied with the resolution of your issue?
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### Issue type

Bug

### Have you reproduced the bug with TensorFlow Nightly?

Yes

### Source

source

### TensorFlow version

0.0.1-nightly.20240417

### Custom code

Yes

### OS platform and distribution

iOS 17

### Mobile device

iPhone 12 mini

### Python version

_No response_

### Bazel version

_No response_

### GCC/compiler version

_No response_

### CUDA/cuDNN version

_No response_

### GPU model and memory

_No response_

### Current behavior?

When I run `Interpreter.copy(data, toInputAt: 0)` or `Interpreter.input(at: 0)` the app crashes with `EXC_BAD_ACCESS` error. The error is thrown here: https://github.com/tensorflow/tensorflow/blob/911c3cce40c53816083d66850b8cbe4bd896c538/tensorflow/lite/swift/Sources/Interpreter.swift#L194

This only happens when I create the interpreter in a separate block than the inference. Please take a look at the code below. If I construct the class and run the `runInference(on:)` method I get `EXC_BAD_ACCESS`. However, running the `runInference(on:, usingModelAt:)` method succeeds. Note that the code to allocate tensors, copy the input and invoke the interpreter is identical.

I wouldn't worry about this and use the second method but creating the interpreter takes about 2 seconds and I'd like to keep it around for multiple inference runs.

### Standalone code to reproduce the issue

```shell
import Foundation
import TensorFlowLite
import TensorFlowLiteCCoreML
import TensorFlowLiteCMetal

class Inference {
    
    var interpreter: Interpreter?
    lazy var inferenceQueue = DispatchQueue(label: "tflite-inference")
    
    init(modelFileUrl: URL) {
        self.inferenceQueue.async {
            do {
                self.interpreter = try self.createInterpreter(modelFileUrl: modelFileUrl)
            } catch {
                
            }
        }
    }
    
    func runInference(on data: Data) {
        self.inferenceQueue.async {
            do {
                guard let interpreter = self.interpreter else {
                    return
                }
                try interpreter.allocateTensors()
                try interpreter.copy(data, toInputAt: 0) // This is the call that causes the EXC_BAD_ACCESS error
                try interpreter.invoke()
                _ = try interpreter.output(at: 0)
            } catch {
                
            }
        }
    }
    
    func createInterpreter(modelFileUrl: URL) throws -> Interpreter {
        let modelData = try Data(contentsOf: modelFileUrl)
        let delegates: [Delegate]
        if let delegate = CoreMLDelegate() {
            delegates = [delegate]
        } else {
            delegates = [MetalDelegate()]
        }
        return try Interpreter(modelData: modelData, delegates: delegates)
    }
    
    /** This method succeeds, no EXC_BAD_ACCESS */
    func runInference(on data: Data, usingModelAt modelFileUrl: URL) throws -> Data {
        let interpreter = try self.createInterpreter(modelFileUrl: modelFileUrl)
        try interpreter.allocateTensors()
        try interpreter.copy(data, toInputAt: 0) // This succeeds
        try interpreter.invoke()
        return try interpreter.output(at: 0).data
    }
}
```


### Relevant log output

_No response_