Excessive Temporary Files Generated by marp-cli on Windows 11​

[maxin9966]

marp-cli version:

marp.exe 4.x.x

Problem Description:

On Windows 11 systems, marp-cli creates numerous temporary folders (named "marp-cli-xxxxx" with random suffixes) in the user's Temp directory. Each folder occupies approximately 18MB of disk space.

In my current workflow, I need to execute marp commands in bulk through the software, which generates these temporary files with each execution. After just 10 days of operation, these temporary files have accumulated to over 400GB on my C: drive, which is concerning for both storage space and system performance.

Questions:

1. Cleanup Process: Are these temporary folders meant to be cleaned up manually, or is there an automated cleanup mechanism that should be handling them?

2. Optimization Possibility: Is there any way to prevent or minimize the generation of these temporary files? Considering that each marp command execution (producing just one PNG image) corresponds to an 18MB temporary folder, the current implementation creates significant disk I/O:
   • This frequent disk activity may impact system performance

   • The constant read/write operations could potentially reduce SSD lifespan

   • Would it be possible to implement an in-memory solution for these temporary files instead of writing to disk?

Additional Context:

• Temp directory location: C:\Users[username]\AppData\Local\Temp\

• Each temporary folder is consistently ~18MB in size

• High volume usage scenario: bulk processing of marp commands

• Visible impact: 400GB+ accumulation within 10 days

[yhatt]

Related?: puppeteer/puppeteer#6414

1. Cleanup Process: Are these temporary folders meant to be cleaned up manually, or is there an automated cleanup mechanism that should be handling them?

"marp-cli-xxxx" directories in the TMP directory will be created as a browser profile when converting Markdown through the browser. It is needed to separate the browser environment from the regular profile, and

The profile directory will be managed by the browser, a separated process from Marp CLI, so Marp does not apply cleaning up. It is left to OS's automatic cleanup.

Because the browser still may be used the profile directory after closing for the postprocess, Puppeteer may hang up if deleted the directory while the postprocess: puppeteer/puppeteer#6291

2. Optimization Possibility: Is there any way to prevent or minimize the generation of these temporary files? Considering that each marp command execution (producing just one PNG image) corresponds to an 18MB temporary folder, the current implementation creates significant disk I/O

An original issue puppeteer/puppeteer#6414 has been closed as not planned, so we think there is no way to use the internal browser without creating the profile directory.

An idea to optimize file I/O caused by the browser is using Marp's server mode (--server) insteand of executing the process each time. While running the server process, Marp CLI will continue to use the same profile directory for converting.

Instead, for reducing the disk usage, you also can manually delete the profile immediately after Marp CLI process. However, it still may bring an issue puppeteer/puppeteer#6291 as previously mentioned.

[maxin9966]

@yhatt

What is the --server mode? I'm currently using the following code:

command = [
f'"{self.marp_executable_path}"',
'--allow-local-files',
'--images', 'png',
'--browser', 'edge',
'--image-scale', '1.0',
'--theme', f'"{os.path.normpath(theme_path)}"',
'-o', f'"{os.path.normpath(output_path)}"',
f'"{os.path.normpath(markdown_path)}"'
]

Can I simply add the -s parameter to enable it?

[yhatt]

Please check out the documentation about the server mode.
https://github.com/marp-team/marp-cli?tab=readme-ov-file#server-mode---server---s

A following is an example in Linux environment:

# Open Marp CLI with server mode as a background process
marp -s /path/to/working-dir &

# Put Markdown file into the working directory for conversion
cp /path/to/markdown.md /path/to/working-dir/working-file.md

# Request a conversion to PNG image (first slide only)
wget http://localhost:8080/working-file.md?png -O output.png

# After conversion, you can clean up the Markdown file
rm /path/to/working-dir/working-file.md

Probably the server mode cannot be used in your case, because you're using --images png. The server mode does not support converting to multiple images.

[maxin9966]

@yhatt To be honest, I don't fully understand the difference between --server mode and regular mode. I just need to generate corresponding PPT images based on the markdown (which requires loading local background images).

Another issue is that since the content is AI-generated, the rendered height often exceeds the boundaries of the PPT slide. This forces me to render repeatedly, adjusting the scaling factor each time. Producing a single image might take seven or eight rendering attempts—not only is this slow, but it also consumes significant IO resources.

Does Marp have any built-in mechanism to ensure that the main content always stays within a predefined area, with automatic scaling if the content overflows?

[yhatt]

In short:

• In regular conversion, a unique directory marp-cli-xxx is created whenever Marp CLI is used to generate PNG images.
  • If the marp command is run multiple times, the same number of directories are also created in the temporary directory.

• Server mode runs the web server for on-demand conversion via HTTP requests, and keeps the marp process running until manually termination.
  • Even if multiple conversion requests are received while the server is running, only one directory marp-cli-xxx will be created, thereby reducing file I/O in the temporary directory.

Including multiple issues in a single issue thread is not recommended by our contributing guideline. Please consider to ask at GitHub Discussions about a new issue.

[maxin9966]

@yhatt It’s really frustrating — the AI-generated content varies in length, forcing us to repeatedly adjust scaling factors just to check if it fits on the slide. We often have to export the same slide multiple times, which slows the computer to a crawl.

Could you provide a sample where content auto-scales to fit within the slide boundaries, or suggest a better solution?

[yhatt]

@maxin9966 I've already responded at marp-team/marp#589. This example should work for determining the best font size automatically. Still have you frastrated about that?