t = db.update_serializability1;
t.drop();

N = 100000;

bulk = t.initializeUnorderedBulkOp()
for ( var i = 0; i < N; i++ ) {
    bulk.insert( { _id : i, a : i, b: N-i, x : 1, y : 1 } );
}
bulk.execute();

t.ensureIndex( { a : 1 } );
t.ensureIndex( { b : 1 } );

s1 = startParallelShell( "db.update_serializability1.update( { a : { $gte : 0 } }, { $set : { b : " + (N+1) + ", x : 2 } }, false, true );" );
s2 = startParallelShell( "db.update_serializability1.update( { b : { $lte : " + N + " } }, { $set : { a : -1, y : 2 } }, false, true );" );

s1();
s2();

// some of each type should have gotten done
assert( t.find( { x : 2 } ).count() > 0 );
assert( t.find( { y : 2 } ).count() > 0 );

// both operations should never happen on a document
assert.eq( 0, t.find( { x : 2, y : 2 } ).count() );