Maybe memory leak?

[2youyou2]

Hi,
I was building a texture packer with sharp, and i use sharp.overlayWith to pack small pictures to a big picture.
I found the way to overlay multiple pictures to a picture in #405. But it seems this will increase memory usage to a huge number and memory will not be release.

Before pack textures: memory usage 88.8 m

After pack textures: Memory usage 1.67 g

I have also disable the cache with sharp.cache(false), but it has no effect.

The example is here: https://github.com/2youyou2/electron-pitfalls
Please follow these steps:

• git clone https://github.com/2youyou2/electron-pitfalls.git
• npm install
• npm start sharp-memory

Thanks for looking this.

[lovell]

Hello, the first thing to try is to force a garbage collection.

Please can you start Electron with --js-flags="--expose-gc" then add a call to gc after processing is complete, e.g.:

        input.then(data => {
          return Sharp(data, opts)
            .toFile(dest);
        }).then(global.gc);

[2youyou2]

Hi, thanks for your quick reply.
Now can use node ./run.js "sharp-memory/" --js-flags='--expose-gc' to enable global.gc

I have updated the code to :

        input.then(data => {
          return Sharp(data, opts)
            .toFile(dest);
        }).then(global.gc);

But it seems still have two problems:

• global.gc not clean all memory increase by sharp, still left about 200m. But if type global.gc in electron inspector console panel after all progress, it will clean all memory.

• Pack textures may use too much memory, the more textures the more memory alloc. In my case, memory usage may increase to 8g. So i add global.gc to every sharp progress to test, see commit. The memory will not grow too much, but i think it may cause window not stable?

[lovell]

The final input is still in scope when then(global.gc) is called so it will not yet be eligible for GC (6000 x 6000 x 4 = 144MB). When calling gc manually from the Electron inspector, input is no longer referenced so is eligible for GC.

The Node/Electron process will grab as much memory as it can before resorting to a GC. If you artificially limit the memory assigned to the process, it will trigger GC more often and free no-longer referenced Buffer data.

See #429 for a more thorough discussion of the memory usage with various versions of Node.

[2youyou2]

Thanks for your answer! I fixed the problems.