# 2.1 线程 (Thread)

* `Thread.backtrace([context, backtracer])`: 生成当前线程的回溯栈，返回形式为一个`NativePointer`数组。如果你想在`Interceptor`的`onEnter`或`onLeave`回调中使用该函数，你需要提供`this.contex`t给`context`参数（不是必须），这样该函数生成的回溯栈会更加准确。不提供`context`参数时，该函数会从当前栈位置自动生成一个`context`，不过由于JavaScript虚拟机栈帧的问题，结果不会很准确。另一个可选参数`backtracer`用于指明使用何种追踪器，其值只能为`Backtracer.FUZZY`或`Backtracer.ACCURATE`，后者是默认值。追踪器的准确度取决于被追踪程序对调试的友好程度以及调试信息，而fuzzy追踪器会对栈进行鉴别，并尝试猜出返回地址，也就是说你会得到一些假阳性错误，不过好处是任何二进制文件都可以使用。生成的回溯栈目前被限制在16个栈帧，如果你想调整，那你必须自己重新编译Frida。

{% code lineNumbers="true" %}

```javascript
const f = Module.getExportByName('libcommonCrypto.dylib', 'CCCryptorCreate');
Interceptor.attach(f, {
  onEnter(args) {
    console.log('CCCryptorCreate called from: \n' + 
        Thread.backtrace(this.context, Backtracer.ACCURATE)
        .map(DebugSymbol.fromAddress).join('\n') + '\n');
  }
});
```

{% endcode %}

* `Thread.sleep(delay)`: 挂起当前线程`delay`秒。比如`delay`为0.05表示休眠50毫秒。


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