Does redis.pipeline.exec() "reset" the pipeline?

I am trying to bulk insert around 500k records into Redis using a pipeline, and my code looks roughly like

const seedCache = async (
  products: Array<Item>,
  chunkSize,
) => {
  for (const chunk of _.chunk(products, chunkSize)) {
    chunk.forEach((item) => {
      pipeline.set(item.id, item.data);
    });
    await pipeline.exec();
    console.log(pipeline.length);
  }
  redis.quit();
};

Essentially, I load chunkSize items into the pipeline, then wait until pipeline.exec() returns, then continue.

I expected that "console.log(pipeline.length)" would be printing "0" every time, since it is only getting run after the pipeline has been flushed to Redis. However, I'm finding that pipeline.length is never getting reset to 0; instead, it just grows and grows until its length is equal to products.length by the end. This is causing my machine to run out of memory for large datasets.

Does anybody know why this is happening? Also, is this even the correct way to bulk insert records into Redis? Since running this script with 5000 products and batch size 100 only inserts 200 into the cache, whereas it does successfully insert an array of 1000 products with the same batch size. The documents are quite large (~5kB), so it needs to be done in batches somehow.