how to start two processes in one Application?

See this: https://stackoverflow.com/a/6567878/850347

You can make more than one process by using setting below.

 android:process=":remote"

Edit1

Alright.
Step1: Make app that has one local process, one global process.

AndroidManifest.xml Note that Setting capital letter for process name makes local process, and small letter process name makes global process.

<?xml version="1.0" encoding="utf-8"?>
<manifest xmlns:android="http://schemas.android.com/apk/res/android"
    package="com.kou.processtest"
    android:versionCode="1"
    android:versionName="1.0" >

    <uses-sdk
        android:minSdkVersion="18"
        android:targetSdkVersion="18" />

    <application>
        <activity
            android:name=".MainActivity"
            android:label="@string/app_name" >
            <intent-filter>
                <action android:name="android.intent.action.MAIN" />

                <category android:name="android.intent.category.LAUNCHER" />
            </intent-filter>
        </activity>
        <activity
            android:name=".LocalProcessActivity"
            android:process=":Local1" />
        <activity
            android:name=".GlobalProcessActivity"
            android:process=".global1" />
    </application>

</manifest>

MainActivity.java

package com.kou.processtest;
import android.app.Activity;
import android.content.Intent;
import android.os.Bundle;
import android.view.View;
import android.view.View.OnClickListener;
import android.widget.Button;

public class MainActivity extends Activity {
    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);

        ((Button) findViewById(R.id.btn1)).setOnClickListener(new OnClickListener() {

            @Override
            public void onClick(View v) {
                Intent intent = new Intent(MainActivity.this, GlobalProcessActivity.class);
                startActivity(intent);
            }
        });

    }

}

GlobalProcessActivity.java

package com.kou.processtest;

import android.app.Activity;
import android.content.Intent;
import android.os.Bundle;
import android.view.View;
import android.view.View.OnClickListener;
import android.widget.Button;

public class GlobalProcessActivity extends Activity {

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_global_process);

        ((Button) findViewById(R.id.btn1)).setOnClickListener(new OnClickListener() {

            @Override
            public void onClick(View v) {
                Intent intent = new Intent(GlobalProcessActivity.this, LocalProcessActivity.class);
                startActivity(intent);
            }
        });

    }
}

LocalProcessActivity.java

package com.kou.processtest;

import android.app.Activity;
import android.os.Bundle;

public class LocalProcessActivity extends Activity {

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_local_process);
    }
}

activity_main.xml

<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:tools="http://schemas.android.com/tools"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    tools:context="${packageName}.${activityClass}" >

    <Button
        android:id="@+id/btn1"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:text="run global process" />

</RelativeLayout>

activity_global_process.xml

<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:tools="http://schemas.android.com/tools"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    tools:context="${packageName}.${activityClass}" >

    <Button
        android:id="@+id/btn1"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:text="run local process" />

</RelativeLayout>

activity_local_process.xml

<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:tools="http://schemas.android.com/tools"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    tools:context="${packageName}.${activityClass}" >

    <Button
        android:id="@+id/btn1"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:text="nothing" />

</RelativeLayout>

Step2: Run app. press button to run global process activity, and local process activity.

Step3: Check process by adb shell, ps. You can see the three processes.

C:\>adb shell ps
u0_a678   19654 2019  553956 33848 ffffffff 00000000 S com.kou.processtest
u0_a678   19680 2019  553952 34008 ffffffff 00000000 S .global1
u0_a678   19701 2019  558020 33588 ffffffff 00000000 S com.kou.processtest:Local1

Step4: Kill application on Setting menu. Setting - App - App info - Force stop

Step5: Run ps again.

Result: all process was killed.
com.kou.processtest and .global1 and com.kou.processtest:Local1 was all killed.