Maya find meshes with holes in them (that are not watertight) by checking if any edge is a boundary edge (not connected to two faces)

maya_query_holes_mesh.py

import maya.api.OpenMaya as om
from maya import cmds


def has_boundaries(mesh):
    sel = om.MSelectionList()
    sel.add(mesh)
    dag = sel.getDagPath(0)
    it = om.MItMeshEdge(dag)
    while not it.isDone():
        if it.onBoundary():
            return True
        it.next()
    return False
    
    
for mesh in cmds.ls(type="mesh"):
    print(mesh, has_boundaries(mesh))

Or by doing the edge count check manually:

import maya.api.OpenMaya as om
from maya import cmds

def has_boundaries(mesh):
    sel = om.MSelectionList()
    sel.add(mesh)
    dag = sel.getDagPath(0)
    it = om.MItMeshEdge(dag)
    while not it.isDone():
        if it.numConnectedFaces() < 2:
            return True
        it.next()
    return False
    
    
for mesh in cmds.ls(type="mesh"):
    print(mesh, has_boundaries(mesh))

I noticed MFnMesh.getHoles exists but in Maya 2024.1 it always seems to return an empty tuple for me.

Doesn't work.

import maya.api.OpenMaya as om
from maya import cmds

def get_holes(mesh):
    sel = om.MSelectionList()
    sel.add(mesh)
    dag = sel.getDagPath(0)
    fn = om.MFnMesh(dag)
    return fn.getHoles()
    
    
for mesh in cmds.ls(type="mesh"):
    print(mesh, get_holes(mesh))

If you allow multiple mesh shells (separate geometry in a single mesh node) to exist but each be watertight the boundary check would still hold. But if you don't allow that you should also check the amount of shells, e.g. maya.cmds.polyEvaluate(mesh, shell=True) != 1. You'd do that before the boundaries check (because it's faster) and that way optimize the query for heavy geometry.