elasticsearch failed to obtain node locks

0x00 事件

重启服务器后，启动 elasticsearch 失败，在日志中观察到以下错误：

[2019-10-25T17:29:54,639][WARN ][o.e.b.ElasticsearchUncaughtExceptionHandler] [test-machine] uncaught exception in thread [main]
org.elasticsearch.bootstrap.StartupException: java.lang.IllegalStateException: failed to obtain node locks, tried [[/var/lib/elasticsearch/sunaw-cluster]] with lock id [0]; maybe these locations are not writable or multiple nodes were started without increasing [node.max_local_storage_nodes] (was [1])?
	at org.elasticsearch.bootstrap.Elasticsearch.init(Elasticsearch.java:140) ~[elasticsearch-6.4.3.jar:6.4.3]
	at org.elasticsearch.bootstrap.Elasticsearch.execute(Elasticsearch.java:127) ~[elasticsearch-6.4.3.jar:6.4.3]
	at org.elasticsearch.cli.EnvironmentAwareCommand.execute(EnvironmentAwareCommand.java:86) ~[elasticsearch-6.4.3.jar:6.4.3]
	at org.elasticsearch.cli.Command.mainWithoutErrorHandling(Command.java:124) ~[elasticsearch-cli-6.4.3.jar:6.4.3]
	at org.elasticsearch.cli.Command.main(Command.java:90) ~[elasticsearch-cli-6.4.3.jar:6.4.3]
	at org.elasticsearch.bootstrap.Elasticsearch.main(Elasticsearch.java:93) ~[elasticsearch-6.4.3.jar:6.4.3]
	at org.elasticsearch.bootstrap.Elasticsearch.main(Elasticsearch.java:86) ~[elasticsearch-6.4.3.jar:6.4.3]
Caused by: java.lang.IllegalStateException: failed to obtain node locks, tried [[/var/lib/elasticsearch/sunaw-cluster]] with lock id [0]; maybe these locations are not writable or multiple nodes were started without increasing [node.max_local_storage_nodes] (was [1])?
	at org.elasticsearch.env.NodeEnvironment.<init>(NodeEnvironment.java:247) ~[elasticsearch-6.4.3.jar:6.4.3]
	at org.elasticsearch.node.Node.<init>(Node.java:274) ~[elasticsearch-6.4.3.jar:6.4.3]
	at org.elasticsearch.node.Node.<init>(Node.java:256) ~[elasticsearch-6.4.3.jar:6.4.3]
	at org.elasticsearch.bootstrap.Bootstrap$5.<init>(Bootstrap.java:213) ~[elasticsearch-6.4.3.jar:6.4.3]
	at org.elasticsearch.bootstrap.Bootstrap.setup(Bootstrap.java:213) ~[elasticsearch-6.4.3.jar:6.4.3]
	at org.elasticsearch.bootstrap.Bootstrap.init(Bootstrap.java:326) ~[elasticsearch-6.4.3.jar:6.4.3]
	at org.elasticsearch.bootstrap.Elasticsearch.init(Elasticsearch.java:136) ~[elasticsearch-6.4.3.jar:6.4.3]

0x01 解决

在一些文章的帮助下查询了进程，发现了另一个 elasticsearch 服务，虽然不清楚是如何启动的，kill 掉即可：

[root@central-machine /usr/share/elasticsearch]#ps -ef | grep elasticsearch
elastic+  1113     1 24 17:17 ?        00:03:19 /bin/java -Xms1g -Xmx1g -XX:+UseConcMarkSweepGC -XX:CMSInitiatingOccupancyFraction=75 -XX:+UseCMSInitiatingOccupancyOnly -XX:+AlwaysPreTouch -Xss1m -Djava.awt.headless=true -Dfile.encoding=UTF-8 -Djna.nosys=true -XX:-OmitStackTraceInFastThrow -Dio.netty.noUnsafe=true -Dio.netty.noKeySetOptimization=true -Dio.netty.recycler.maxCapacityPerThread=0 -Dlog4j.shutdownHookEnabled=false -Dlog4j2.disable.jmx=true -Djava.io.tmpdir=/tmp/elasticsearch.O6OSL2h2 -XX:+HeapDumpOnOutOfMemoryError -XX:HeapDumpPath=/var/lib/elasticsearch -XX:ErrorFile=/var/log/elasticsearch/hs_err_pid%p.log -XX:+PrintGCDetails -XX:+PrintGCDateStamps -XX:+PrintTenuringDistribution -XX:+PrintGCApplicationStoppedTime -Xloggc:/var/log/elasticsearch/gc.log -XX:+UseGCLogFileRotation -XX:NumberOfGCLogFiles=32 -XX:GCLogFileSize=64m -Des.path.home=/usr/share/elasticsearch -Des.path.conf=/etc/elasticsearch -Des.distribution.flavor=default -Des.distribution.type=rpm -cp /usr/share/elasticsearch/lib/* org.elasticsearch.bootstrap.Elasticsearch -p /var/run/elasticsearch/elasticsearch.pid --quiet
elastic+  5193  1113  0 17:17 ?        00:00:00 /usr/share/elasticsearch/modules/x-pack-ml/platform/linux-x86_64/bin/controller
root     14123 10944  0 17:30 pts/0    00:00:00 grep --color=auto elasticsearch
[root@central-machine /usr/share/elasticsearch]#kill -9 1113
[root@central-machine /usr/share/elasticsearch]#ps -ef | grep elasticsearch
root     14151 10944  0 17:31 pts/0    00:00:00 grep --color=auto elasticsearch

kill 掉之后，再启动 elasticsearch，没有再出现此错误，服务也正常运行。