Armin Braun a2c49a4f02
Reduce Heap Use during Shard Snapshot (#60370) (#60440)
Instances of `BlobStoreIndexShardSnapshots` can be of non-trivial size. In case of snapshotting a larger
number of shards the previous execution order would lead to memory use proportional to the number of shards
for these objects. With this change, the number of these objects on heap is bounded by the size of the snapshot
pool (except for in the BwC format path).
This PR makes it so that they are written to the repository at the earliest possible point in time
so that they can be garbage collected.
If shard generations are used, we can safely write these right at the beginning of the shard snapshot.
If shard generations are not used we can only write them at the end of the shard snapshot after all
other blobs have been written.

Closes #60173
2020-07-30 10:45:00 +02:00
..