My goal is to have multiple markers with text on each on the Android Google Maps API v2 map. The info windows approach (showInfoWindow()) is not suitable, because only one info window is displayed at a time. For example I want to have something like this: 
As you can see each marker has its own data (number for this example) displayed all the time. How can I achieve this with Android Google Maps API v2?
to do that you'll have to customize the icon of each individual marker to be what you need. Here's the link: https://developers.google.com/maps/documentation/android/marker#customize_a_marker
Then you can put some PNG resources (a blue, a yellow and a red), and at runtime get correct Bitmap, write the text on the bitmap by code, and then set as the custom-marker with the fromBitmap (Bitmap image) method.
try out this
LinearLayout tv = (LinearLayout) this.getLayoutInflater().inflate(R.layout.marker_dialog, null, false);
tv.measure(View.MeasureSpec.makeMeasureSpec(0, View.MeasureSpec.UNSPECIFIED),
View.MeasureSpec.makeMeasureSpec(0, View.MeasureSpec.UNSPECIFIED));
tv.layout(0, 0, tv.getMeasuredWidth(), tv.getMeasuredHeight());
tv.setDrawingCacheEnabled(true);
tv.buildDrawingCache();
Bitmap bm = tv.getDrawingCache();
LatLng latLng = new LatLng(latitudemy, longitudemy);
BitmapDescriptor icon = BitmapDescriptorFactory.fromBitmap(bm);
BitmapDescriptorFactory.fromResource(R.mipmap.ic_launcher);
map.addMarker(new MarkerOptions().position(new LatLng(latitudemy, longitudemy)).title("origin").snippet("Srivastava").icon(icon));
// Showing the current location in Google Map
map.addMarker(new MarkerOptions().position(new LatLng(latitude, longitude)).title("destination").snippet("Srivastava").icon(icon));
As an update:
android maps utils now has a Marker Clustering Utility
https://developers.google.com/maps/documentation/android/utility/marker-clustering
https://github.com/googlemaps/android-maps-utils
