Question: I am using Python 2.7.

I have been experimenting with the interpreter and found out the following unusual thing. I wrote the following code and it's working:

```
    def func():
        a = 5 ;
        print a

```

When I call this function, it gives the required output in the interpreter, not giving any syntax error, despite using the semicolon. Here is the screenshot:

![Enter image description here](https://i.stack.imgur.com/f6emO.png)

Why is it not giving a *syntax error*?

Answer: 
If your implementation for `AsyncTask` is correct, then the possible reason for this behaviour is because the default `executor` for `AsyncTasks` is `SERIAL_EXECUTOR`. 

To run multiple `AsyncTask` instances in parallel (not serially.. no one after other). execute them as follows:

```
if (Build.VERSION.SDK_INT >= 11) {
    outstandingTask.executeOnExecutor(AsyncTask.THREAD_POOL_EXECUTOR);
} else {
    outstandingTask.execute();
}

```

From the [documentation](http://developer.android.com/reference/android/os/AsyncTask.html#):

> 
> When first introduced, `AsyncTask` were executed serially on a single
>  background thread. Starting with `DONUT`, this was changed to a pool of
>  threads allowing multiple tasks to operate in parallel. Starting with
>  `HONEYCOMB`, tasks are executed on a single thread to avoid common
>  application errors caused by parallel execution.
> 
> 
> If you truly want parallel execution, you can invoke
>  `executeOnExecutor(java.util.concurrent. Executor, Object[])` with
>  `THREAD_POOL_EXECUTOR`.
> 
> 
>
Asynchronous task always run in background.It will not disturb the any process.Might be your first Asynchronous task holding some resources and that one also using for second one.So its waiting for the resource.

Please have look @ your code carefully or paste your code..