Q:

Is a good practice create anonymous AsyncTask for parallel small known freeze process?

E.g.: you gonna do something that will take a few seconds and don't wanna freeze your UI thred, right? You could use an AsyncTask but you don't wanna create a external (or inner) class to solve a small freeze problem.
So, is a good pratice do it?
package com.example.stackoverflowsandbox;

import android.os.AsyncTask;

public class Foo {
    // E.g. before call foo method you change you Activity to loading state.
    private void foo() {
        new AsyncTask<Void, Void, Void>() {
            @Override
            protected Void doInBackground( final Void ... params ) {
                // something you know that will take a few seconds

                return null;
            }

            @Override
            protected void onPostExecute( final Void result ) {
                // continue what you are doing...

                Foo.this.continueSomething();
            }
        }.execute();
    }

    private void continueSomething() {
        // some code...
    }
}

I've faced with that when I compressing Bitmaps and looping big array to update some data inside items.

A:

Yes, but not the way you do it.
Remember that starting Honeycomb the default execution model of AsyncTasks is serial:
  new AsyncTask<Void, Void, Void>() {
         ....
         ....
  }.execute(); <------ serial execution

Instead use a thread pool executor:
  new AsyncTask<Void, Void, Void>() {
         ....
         ....
  }.executeOnExecutor(AsyncTask.THREAD_POOL_EXECUTOR, null); <------ parallel execution

