## The problem

Batch file existence checks against GCS (bucket.file(fileName).exists() in batches of 20) produce lots of socket hang up errors from the @google-cloud/storage Node SDK. The SDK was not reusing connections properly, so bursts of requests exhausted sockets.

## What fixed it

Fixed upstream in the @google-cloud/storage SDK: the reporter re-tested with 7 files and all streams succeeded after the fix. Upgrade @google-cloud/storage to a version containing the fix and retry the batch checks. If you still see socket hang ups on an old version, the practical mitigation is to serialize the checks or increase the HTTP agent's maxSockets.