Question

I have a servlet with an API that delivers images from GET requests. The servlet creates a data file of CAD commands based on the parameters of the GET request. This data file is then delivered to an image parser, which creates an image on the file system. The servlet reads the image and returns the bytes on the response.

All of the IO and the calling of the image parser program can be very taxing and images of around 80kb are rendering in 3-4000ms on a local system.

There are roughly 20 parameters that make up the GET request. Each correlates to a different portion of the image. So, the combinations of possible images is extremely large.

To alleviate the loading time, I plan to store BLOBs of rendered images in a database. If a GET request matches one previously executed, I will pull from cache. Else, I will render a new one. This does not fix “first-time” run, but will help “n+1 runs”.

Any other ideas on how I can improve performance?

Answer 1

you can store file on you disk,and image path in database,because database storage is usually more expensive than file system storage.

sort the http get parameters and hash them as an index to that image record for fast query by parameters.

to make sure your program not crush when disk capacity not enough,you should remove the the unused or rarely used record:

store a lastAccessedTime for each record,updated each time when the image is requested.

using a scheduler to check lastAccessedTime,removing records which is lower than a specified weight.
you can use different strategy to calculate the weight,such as lastAccessedTime,accessedCount,image size,etc.