WeasyPrint: Memory leak problem

Hello, we encountered a memory leak when using weasyprint. The phenomenon is that once the memory goes up, it can’t go down again. Prometheus monitoring screenshot： cpu: memory: You can see that CPU will drop, but memory will never drop.

We use custom fonts, a lot of pictures and SVG. I don’t know if it will be related to them.

Problem recurrence steps

We are running in docker： dockerfile:

FROM python:3.8-bullseye

RUN apt-get update

RUN apt-get install -y python3-cffi python3-brotli libpango-1.0-0 libpangoft2-1.0-0 --no-install-recommends

RUN mkdir ~/.fonts

RUN cp SourceHanSerifCN-Light.ttf ~/.fonts/

SourceHanSerifCN-Light.ttf We used the latest weasyprint：

pip freeze

aliyun-python-sdk-core==2.13.35
aliyun-python-sdk-kms==2.15.0
amqp==2.6.1
bayua==0.0.3
billiard==3.6.4.0
blinker==1.4
Brotli==1.0.9
cachetools==4.2.4
cachext==1.1.1
celery==4.4.7
certifi==2021.10.8
cffi==1.15.0
charset-normalizer==2.0.7
coast==1.4.0
crcmod==1.7
cryptography==35.0.0
cssselect2==0.4.1
elastic-apm==5.10.1
fonttools==4.28.1
grpcio==1.37.1
grpcio-tools==1.37.1
html5lib==1.1
idna==3.3
Jinja2==3.0.3
jmespath==0.10.0
kombu==4.6.11
MarkupSafe==2.0.1
oss2==2.15.0
pendulum==2.1.2
Pillow==8.4.0
protobuf==3.19.1
protos-py==0+untagged.247.gbb6fa5f
pycparser==2.21
pycryptodome==3.11.0
pydyf==0.1.2
PyMuPDF==1.19.1
pyphen==0.11.0
python-dateutil==2.8.2
pytz==2021.3
pytzdata==2020.1
redis==3.5.3
requests==2.26.0
sea==2.3.1
SensorsAnalyticsSDK==1.10.3
sensorsdata-ext==1.0.2
sentry-sdk==1.4.3
six==1.16.0
tinycss2==1.1.0
urllib3==1.26.7
vine==1.3.0
weasyprint==53.4
webencodings==0.5.1
zopfli==0.1.9

Running code

import tempfile

from weasyprint import CSS, HTML
from weasyprint.text.fonts import FontConfiguration

font_config = FontConfiguration()
css = CSS(
    string="""
    @font-face {
        font-family: SourceHanSerifCN-Light;
        src: url("SourceHanSerifCN-Light.ttf");
    }""",
    font_config=font_config,
)

html_url = ""

temp_pdf_file = tempfile.NamedTemporaryFile(mode="w", suffix=".pdf")
HTML(html_url).write_pdf(
    temp_pdf_file.name, stylesheets=[css], font_config=font_config
)
temp_pdf_file.close()

HTML page to be converted (this is just a demo, which is actually much larger than it)： https://media-zip1.baydn.com/storage_media_zip/zonyme/182d435ec35fabee217b868a5d2b1e94.49ea39443dfa775bc73b0292a088c88b.html

At first, I thought HTML was too big, so I split HTML into several sub HTML, then converted it into PDF, and finally spliced the PDF, but it would leak memory

like this：

import tempfile

from weasyprint import CSS, HTML
from weasyprint.text.fonts import FontConfiguration

font_config = FontConfiguration()
css = CSS(
    string="""
    @font-face {
        font-family: SourceHanSerifCN-Light;
        src: url("SourceHanSerifCN-Light.ttf");
    }""",
    font_config=font_config,
)

html_url = []

for item in html_url:
  temp_pdf_file = tempfile.NamedTemporaryFile(mode="w", suffix=".pdf")
  HTML(item).write_pdf(
      temp_pdf_file.name, stylesheets=[css], font_config=font_config
  )
 temp_pdf_file.close()
....
merge pdf

I really hope you can see this problem and help fix it