发生了什么
当我重复查询时，Elastic Search突然停止工作。
我将堆大小从1GB增加到2GB，然后又增加到4GB，但是没有用。
当前的堆使用量仅为分配的4Gb的20％，但这仍然是为什么ES会因OOM而失败的原因？
ElasticSearch日志：
2019-11-11T11:12:16,654][INFO ][o.e.c.r.a.AllocationService] [es-stg] Cluster health status changed from [RED] to [YELLOW] (reason: [shards started [[.kibana_1][0]] ...])
[2019-11-11T11:12:51,447][INFO ][o.e.c.m.MetaDataIndexTemplateService] [es-stg] adding template [kibana_index_template:.kibana] for index patterns [.kibana]
[2019-11-11T11:13:10,527][INFO ][o.e.m.j.JvmGcMonitorService] [es-stg] [gc][71] overhead,spent [418ms] collecting in the last [1s]
[2019-11-11T11:13:16,619][INFO ][o.e.m.j.JvmGcMonitorService] [es-stg] [gc][77] overhead,spent [313ms] collecting in the last [1s]
[2019-11-11T11:13:21,187][WARN ][o.e.m.j.JvmGcMonitorService] [es-stg] [gc][80] overhead,spent [2.4s] collecting in the last [2.5s]
[2019-11-11T11:13:25,396][WARN ][o.e.m.j.JvmGcMonitorService] [es-stg] [gc][83] overhead,spent [2s] collecting in the last [2.1s]
[2019-11-11T11:13:27,983][WARN ][o.e.m.j.JvmGcMonitorService] [es-stg] [gc][84] overhead,spent [2.3s] collecting in the last [2.6s]
[2019-11-11T11:13:30,029][WARN ][o.e.m.j.JvmGcMonitorService] [es-stg] [gc][85] overhead,spent [2s] collecting in the last [2s]
[2019-11-11T11:13:34,184][WARN ][o.e.m.j.JvmGcMonitorService] [es-stg] [gc][86] overhead,spent [4.1s] collecting in the last [4.1s]
[2019-11-11T11:14:31,155][WARN ][o.e.c.InternalClusterInfoService] [es-stg] Failed to update node information for ClusterInfoUpdateJob within 15s timeout
[2019-11-11T11:14:31,172][WARN ][o.e.m.j.JvmGcMonitorService] [es-stg] [gc][87] overhead,spent [18.2s] collecting in the last [18.3s]
[2019-11-11T11:14:31,215][ERROR][o.e.x.m.c.i.IndexStatsCollector] [es-stg] collector [index-stats] timed out when collecting data
[2019-11-11T11:14:31,210][ERROR][o.e.b.ElasticsearchUncaughtExceptionHandler] [es-stg] fatal error in thread [elasticsearch[es-stg][search][T#6]],exiting
java.lang.OutOfMemoryError: Java heap space
规范：
Ubuntu：16.04
内存：8Gb
JVM内存：4Gb
以下结果：
http://localhost:9200/_cat/allocation
84 4.6gb 55.1gb 22.2gb 77.3gb 71 206.189.140.50 206.189.140.50 es-stg
42 UNASSIGNED
http://localhost:9200/_cat/fielddata?v
id host ip node field size
o_KWnYBuR-aimAl1VUtygA ip ip es-stg shard.node 2.7kb
o_KWnYBuR-aimAl1VUtygA ip ip es-stg transaction.type 704b
o_KWnYBuR-aimAl1VUtygA ip ip es-stg transaction.name.keyword 1kb
o_KWnYBuR-aimAl1VUtygA ip ip es-stg kibana_stats.kibana.status 2kb
o_KWnYBuR-aimAl1VUtygA ip ip es-stg beat.hostname 5.8kb
o_KWnYBuR-aimAl1VUtygA ip ip es-stg transaction.result 704b
o_KWnYBuR-aimAl1VUtygA ip ip es-stg kibana_stats.kibana.uuid 2kb
o_KWnYBuR-aimAl1VUtygA ip ip es-stg source_node.name 2.7kb
o_KWnYBuR-aimAl1VUtygA ip ip es-stg shard.index 12.1kb
o_KWnYBuR-aimAl1VUtygA ip ip es-stg shard.state 6.6kb
o_KWnYBuR-aimAl1VUtygA ip ip es-stg context.service.agent.name 2.2kb
o_KWnYBuR-aimAl1VUtygA ip ip es-stg source_node.uuid 2.7kb
http://localhost:9200/_cat/nodes?v
ip heap.percent ram.percent cpu load_1m load_5m load_15m node.role master name
ip 18 98 2 0.04 0.08 0.06 mdi * es-stg
http://localhost:9200/_cluster/settings
{persistent: {xpack: {monitoring: {collection: {enabled: "true"}}}},transient: { }}
预期：
需要弹性搜索才能正常运行。
（较少的磁盘空间与此问题有关吗？）