Boost Image Delivery Speed with Bolt: A Fast Real-Time Image Resizing Server

Bolt is a real‑time image cropping and compression server that processes each image only once, making it more than twice as fast as Nginx’s image_filter.

It uses a single‑threaded processing model per image, so concurrent requests for the same image do not trigger duplicate work.

Bolt replaces the cache mechanism: processed images are stored and not re‑processed unless memory is insufficient, at which point an LRU algorithm evicts rarely accessed images. The maximum memory can be set with the "--max-cache" startup parameter.

Use cases

Bolt is suitable for servers with abundant memory and CPU, and it reduces disk usage while accelerating image loading.

Installation

1) Install libevent (http://libevent.org/)

2) Install ImageMagick (http://www.imagemagick.org/script/index.php)

3) Install Bolt

$ git clone https://git.oschina.net/liexusong/bolt.git $ cd bolt $ make

Usage

Access images via URL pattern: http://your-host/filename_(width)x(height)_(quality).jpg

Bolt startup options

--host: set binding IP

--port: set listening port

--workers: number of worker threads for image processing

--logfile: path to log file

--logmark: log level (DEBUG|NOTICE|ALERT|ERROR)

--max-cache: maximum memory for Bolt (bytes)

--gc-threshold: GC threshold as a percentage of max-cache (0‑99)

--path: source image directory

--watermark: watermark image path

--daemon: run as daemon

--help: display help