Loading data using `UnstructuredURLLoader` of LangChain halts with `TP_NUM_C_BUFS too small: 50` – Langchain

Ali Hasan
artificial-intelligence langchain py-langchain python-3.x

Quick Fix: Install python-magic and python-magic-bin using pip to resolve the issue.

The Problem:

Loading HTML files from a list of URLs using the UnstructuredURLLoader of LangChain stalls without loading any data. The error TP_NUM_C_BUFS too small: 50 appears in the stack trace, but the issue persists despite executing the script on Windows command prompt as suggested in a resolved GitHub issue.

The Solutions:


The error TPNUMBUF too small occurs when the temporary buffer allocated to store the parsed HTML document is too small to hold the entire document. This can happen when the HTML document is very large or complex.

To resolve this error, you can increase the size of the temporary buffer by setting the max_buffer_size parameter of the UnstructuredURLLoader constructor. For example:

loader = UnstructuredURLLoader(urls, max_buffer_size=1024 * 1024 * 10)  # 10MB buffer

You should also ensure that the system has enough memory available to handle the larger buffer size. If necessary, you can increase the system’s memory limit using the ulimit command. For example, to set the memory limit to 1GB:

ulimit -v 1024 * 1024 * 1024

Once you have increased the buffer size and ensured that the system has enough memory, you should be able to load the HTML documents without encountering the TPNUMBUF too small error.


Why the error TP_NUM_C_BUFS too small: 50 occurs when loading HTML files with UnstructuredURLLoader in LangChain?

Installing libmagic via Python may resolve the issue.

What additional packages may be necessary to parse HTML and PDF files using url_loader.load()?

tabulate, pdf2image, and pytesseract