Memory Leak due to readFragment

[ryansydnor]

Intended outcome:
When using readFragment against data that is already in the cache, node's memory usage should remain stable.

Actual outcome:
Our node server's memory usage spiked once we started using readFragment in a heavily trafficked part of our application:

How to reproduce the issue:

const ApolloClient = require('apollo-client').ApolloClient
const HttpLink = require('apollo-link-http').HttpLink;
const InMemoryCache = require('apollo-cache-inmemory').InMemoryCache;
const gql = require('graphql-tag');
const fetch = require('node-fetch');

const client = new ApolloClient({
  link: new HttpLink({
    uri: 'https://www.teacherspayteachers.com/graph/graphql',
    fetch
  }),
  cache: new InMemoryCache()
});

client.query({
  query: gql`
    query ProductTest {
      products(ids:[968647]) {
        id
        description
        name
      }
    }
  `,
}).then(data => leakMemory());

const leakMemory = () => {
  setInterval(() => {
      client.readFragment({
        id: 'Product:968647',
        fragment: gql`
          fragment Leak on Product {
            id
            name
          }
        `
      });
      console.log(process.memoryUsage());
  }, 5);
};

I've tracked the issue down to this line:

apollo-client/packages/apollo-utilities/src/transform.ts

Line 184 in 311d205

added.set(doc, docClone);

We are never getting cache hits despite using exactly the same fragment because I believe we are losing our equality reference due to object instantiation here:

apollo-client/packages/apollo-utilities/src/fragments.ts

Line 68 in 311d205

const query: DocumentNode = {

.

Version

• apollo-client@2.2.6

/label memory-leak

[jonmagic]

We're experiencing the same bug I think, I noticed while memory profiling:

[edqd]

Is it possible that what we're experiencing is a very similar/same bug, but without any usage of readFragment? Although we do use cacheRedirects.

Memory usage

Memory profiling

[jakepusateri]

I think #3444 fixed this issue by removing the internal caches in this file. It should be in the next release of apollo-utilities, having been merged to master already.

[hwillson]

Thanks for reminding us about this issue @jakepusateri. Yes, this should now be fixed and will be included in the release of apollo-client 2.3.2 this Tuesday (May 29th, 2018).