How to Manipulate a 30 Million Character String Without Running Out of Memory?

Manipulating a 30 Million Character String: Avoiding Memory Allocation Errors

Utilizing curl to retrieve a CSV data feed from a vendor presents a challenge when manipulating such a large file size. Common approaches of exploding the contents by separators (e.g., r and n) result in "out of memory" errors due to the immense size (approximately 30.5 million characters). This article explores alternative solutions to overcome this problem.

While it is not feasible to store the entire file in memory, one option is to employ CURLOPT_FILE to redirect the contents into a file on disk. However, this approach may not align with the desired workflow, as it involves creating a physical file.

An alternative solution is to define a custom stream wrapper, register it, and utilize it instead of a real file with CURLOPT_FILE. This stream wrapper can be designed to process data in chunks as they arrive, efficiently avoiding memory allocation issues.

To illustrate this approach, let's create a MyStream class that extends the streamWrapper class. In the stream_write method, we can exploit the explode function to extract lines from the incoming data chunks. Since data is typically received in smaller chunks (e.g., 8192 bytes), we can operate on these smaller portions rather than attempting to manipulate the entire file at once.

By registering this custom stream wrapper with a unique protocol (e.g., "test") and using it in the curl configuration with CURLOPT_FILE, we can leverage the stream_write method to work on data incrementally as it is received. This technique allows for efficient manipulation of large strings without inducing memory allocation errors.

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