How Can I Efficiently Load Large Excel Files into PHPExcel Without Running Out of Memory?

PHPExcel Out of Memory Issues

Loading large Excel tables using PHPExcel can result in memory exhaustion, despite allowing generous memory allocation. Understanding the memory allocation process is crucial to resolving this issue.

Factors Affecting Memory Consumption

The memory requirements of PHPExcel primarily depend on the number of cells in the loaded worksheets. The average memory usage is approximately 1k per cell. Therefore, a workbook with 5M cells would require around 5GB of memory.

Optimizations

To mitigate memory consumption, several optimizations can be implemented:

• Limiting Loaded Worksheets: Only load specific worksheets using setLoadSheetsOnly().
• Read Filters: Implement a read filter to select only the necessary cells.
• Reading in Chunks: Load the workbook in iterations to keep only a set number of rows in memory at a time.
• Read Data Only: Load only the cell values without formatting using setReadDataOnly(true).
• Cell Caching: Store cells in a compressed format or outside PHP's memory to reduce memory footprint.

Additional Tips

In your code, the $arrayData array accumulates data, potentially exacerbating memory usage. Instead, consider utilizing PHPExcel's toArray() method or its new rangeToArray() method, which can create an associative array of the data without the need for the intermediate array.

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