Async unzip maxing out CPU and memory for some files

[tmatson98]

How to reproduce

The issue can be reproduced with the following code:

const sync = false;
const contents = {};
for (let i = 0; i < 80; i += 1) {
  contents[`file-${i}`] = new Uint8Array(Array.from({ length: 1024 * 1024 }, () => Math.floor(Math.random() * 256)));
}
const zipped = zipSync(contents);
console.log('Unzipping');
const start = performance.now();
if (sync) {
  unzipSync(zipped);
  console.log(`${performance.now() - start} ms`);
} else {
  unzip(zipped, null, () => {
    console.log(`${performance.now() - start} ms`);
  });
}

The problem Trying to decompress a moderately large ZIP file (~80 MB) containing files of 200 kB to 1 MB using the async unzip function maxes out my system memory and CPU. Using unzipSync instead works perfectly and takes less an 100ms in the above code, while unzip takes a full minute. Increasing the ZIP size to 150 MB can cause unzip to fail with this error:

Uncaught DOMException: The object could not be cloned.
    cbify browser.js:910
    inflate browser.js:1174
    _loop_3 browser.js:2547
    unzip browser.js:2556

Decompressing a ZIP with 8 10MB files works okay so it seems to be mainly caused by the number of files, but the unzipSync function is still much faster decompressing it. Using a performance profiler the issue seems to be with the postMessage WebWorker function.

Test machine has an i7 6700, 16GB RAM

[101arrowz]

I'll try to address this in the next update. unzip should be strictly faster than unzipSync for sufficiently large ZIPs.

[101arrowz]

Reproduced locally. I have a potential fix for the slow performance but the crashing on ZIPs with hundreds of medium-size files might be more related to #58 than anything.

[101arrowz]

Fixed in v0.8.2.