TiDB OOM when init stats

[hawkingrei]

Bug Report

Please answer these questions before submitting your issue. Thanks!

1. Minimal reproduce step (Required)

1. TiDB start and load stats
2. TiDB OOM

2. What did you expect to see? (Required)

3. What did you see instead (Required)

OOM in the (*infoSchema).TableByName

4. What is your TiDB version? (Required)