Possible Memory Leak in Parsing a XML File?

I have a long running script, which parses a large XML file(~9GB) and inserts data into a database in chunks. This is what that looks like,

import lxml.etree as ET
import gc

def __get_elements1(self):
    context = ET.iterparse(tmp_folder + file_path, events=("start", "end"), tag='Elements1')

    elements = []

    try:
        for event, element in context:
            if event == "end":
                elements_result = tuple([child.text for child in element])
                elements.append(elements_result)

                element.clear()
                while element.getprevious() is not None:
                    del element.getparent()[0]

                if len(elements) == self.chunk_size:
                    # insert data to database

        if len(elments) > 0:
           # insert data to database
    except Exception as e:
        logging.error(e)

    del context
    del elements

    gc.collect()

Here, I am looking for elements with a specific tag and parsing them. Now, I have few other functions that parse different tags in the same file. The code is pretty much the same with very slight modifications. I actually want to run these parallelly, but even when I run them sequentially, I am faced with a problem.

My first function runs fine and without consuming much resources, however, when I get to my second function, memory consumption just shoots up and my application fails. This does not make sense, especially because I am parsing the elements with the most data through my first function. My second function can be thought to look something like this,

def __get_elements2(self):
    context = ET.iterparse(tmp_folder + file_path, events=("start", "end"), tag='Elements2')

    elements = []

    try:
        for event, element in context:
            if event == "end":
                elements_result = tuple([child.text for child in element])
                elements.append(elements_result)

                element.clear()
                while element.getprevious() is not None:
                    del element.getparent()[0]

                if len(elements) == self.chunk_size:
                    # insert data to database

        if len(elments) > 0:
           # insert data to database
    except Exception as e:
        logging.error(e)

    del context
    del elements

    gc.collect()

Notice that tag given to the iterparse function above is different.

What could be the cause of this? Is it a possible memory leak? I cannot think of anything else. How do I resolve this?