这种情况经常发生，elasticsearch无法分配主分片，并且群集变为红色。
details": "failed shard on node [M7ujUGxFScWSHFtnQMJdhQ]: failed to create shard, failure IOException[failed to obtain in-memory shard lock]; nested: ShardLockObtainFailedException[[ftplogs-2017.05.01-gdpr][0]: obtaining shard lock timed out after 5000ms]; ",
然后我必须运行：
POST _cluster/reroute?retry_failed=true
此锁定问题的原因可能是什么？