elasticsearch开启gc日志

在jvm.properties中gc日志相关配置默认是注释掉的，放开对应配置项即可

## GC logging

-XX:+PrintGCDetails
-XX:+PrintGCTimeStamps
-XX:+PrintGCDateStamps
#-XX:+PrintClassHistogram
#-XX:+PrintTenuringDistribution
#-XX:+PrintGCApplicationStoppedTime

# log GC status to a file with time stamps
# ensure the directory exists
-Xloggc:${sys:es.logs.base_path}${sys:file.separator}${sys:es.logs.cluster_name}-show-gc.log

# By default, the GC log file will not rotate.
# By uncommenting the lines below, the GC log file
# will be rotated every 128MB at most 32 times.
-XX:+UseGCLogFileRotation
-XX:NumberOfGCLogFiles=32
-XX:GCLogFileSize=1K