php-memory-optimisation

PHP Memory Optimisation Standards

Guidance and automated checks to reduce peak memory usage in PHP applications. Based on widely accepted practices and the article "PHP Memory Optimization Tips" by Khouloud Haddad.

actions:

• type: enforce conditions:

  Avoid loading entire DB result sets into memory.

  • pattern: "->fetchAll\(" message: "Avoid fetchAll() on large result sets; iterate with fetch() in a loop or wrap with a generator (yield)."

  • pattern: "\bmysqli_fetch_all\(" message: "Avoid mysqli_fetch_all() for large queries; prefer streaming fetch (e.g., mysqli_fetch_assoc in a loop)."

  Avoid repeated full-file loads inside loops.

  • pattern: "foreach\s*\([^)]\)\s\{[^}]*file_get_contents\(" message: "Avoid file_get_contents() inside loops; stream with SplFileObject or read once and reuse."

  Avoid array_merge in tight loops as it copies arrays.

  • pattern: "foreach\s*\([^)]\)\s\{[^}]=\sarray_merge\(" message: "Avoid array_merge() inside loops; append elements directly or preallocate arrays."

  Use caution with range() on large ranges (allocates full array).

  • pattern: "\brange\s*\(" message: "range() allocates full arrays; for large ranges consider generators (yield) to avoid high memory."

• type: suggest message: | PHP memory optimisation recommendations:

  • Stream database results: Prefer $stmt->fetch(PDO::FETCH_ASSOC) in a while loop or use generators instead of fetchAll().
  • Use generators (yield): Iterate large datasets without allocating full arrays.
  • Stream files: Use SplFileObject or chunked reads instead of file_get_contents() for large files.
  • Minimise array copying: Avoid array_merge() in loops; push items directly or pre-size with known capacity (e.g., SplFixedArray).
  • Free memory explicitly: unset($var) after large data is no longer needed; consider gc_collect_cycles() for long-running scripts.
  • Profile memory: Use memory_get_usage() and tools like Xdebug/Blackfire to spot peaks.
  • OPcache: Ensure OPcache is enabled and sized appropriately in production.

• type: validate conditions:

  Detect full-file reads that likely could be streamed.

  • pattern: "\bfile\s*\(" message: "file() reads entire files into memory; prefer SplFileObject for line-by-line streaming."

metadata: priority: high version: 1.0

actions:

• type: suggest message: | OPcache recommendations (php.ini):

  • Set opcache.enable=1 and opcache.enable_cli=1 for CLI scripts that process large datasets.
  • Size memory pool appropriately, e.g., opcache.memory_consumption=128 (adjust to your project).
  • Consider opcache.interned_strings_buffer and opcache.max_accelerated_files for larger codebases.

• type: enforce conditions:

  • pattern: "(?mi)^opcache\.enable\s*=\s*0" message: "Enable OPcache in production (set opcache.enable=1) to reduce memory and CPU overhead."

metadata: priority: medium version: 1.0