Occasional 429 errors (Too Many Requests) in Drive activity polls

[jpd236]

My server logs show occasional instances of 429s in the Drive activity queries:

code: 429,
  errors: [
    {
      message: 'Resource has been exhausted (e.g. check quota).',
      domain: 'global',
      reason: 'rateLimitExceeded'
    }
  ]
}

The overall error rate looks quite low in the console (0.02%), though it is a bit noisy. From what I can tell we're doing between 10-15 queries per minute, and the limit per minute per user is 100.

It seems like there might be some retries here already; I wonder if we just need to back off a bit more in this case.