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VIPS Performance Tuning

imagor uses libvips for image processing. libvips provides several configuration options to tune performance and resource usage:

VIPS_CONCURRENCY controls the number of threads libvips uses for image operations:

VIPS_CONCURRENCY=1    # Single-threaded (default)
VIPS_CONCURRENCY=-1   # Use all available CPU cores
VIPS_CONCURRENCY=4    # Use 4 threads

Important: VIPS_CONCURRENCY is a global setting that controls threading within each image operation, not the number of concurrent requests.

  • Default (1): Single-threaded processing. Recommended for most deployments where you handle concurrency at the application level (multiple imagor processes/containers).
  • -1 (auto): Uses all CPU cores. Can improve performance for individual large images but may cause resource contention under high request concurrency.
  • Custom value: Set to a specific number of threads for fine-tuned control.

For high-traffic deployments, it's generally better to scale horizontally (more imagor instances) rather than increasing VIPS_CONCURRENCY.

libvips also has a built-in operation cache (VIPS_MAX_CACHE_MEM, VIPS_MAX_CACHE_SIZE, VIPS_MAX_CACHE_FILES) that reuses recently computed operations. For imagor's typical workload, each request processes a different source image so this cache rarely gets hits — the defaults (0 = disabled) are appropriate. See libvips documentation for details.