Elasticsearch GC log message

[9787d569382ad9fcce95 (雷惜福)]

Hi,
I install Elasticsearch 6.2.4 by .rpm (elasticsearch-6.2.4.rpm) for testing purpose.

After installation, elasticsearch service running normally and no error log found in /var/log/elasticsearch.log

However, there are lots of message keep printing in gc.log.0.current as below,

2018-06-11T05:57:52.786+0000: 2.883: [GC (Allocation Failure) 2018-06-11T05:57:52.786+0000: 2.883: [ParNew
Desired survivor size 8716288 bytes, new threshold 6 (max 6)
- age   1:    4236992 bytes,    4236992 total
: 147899K->6846K(153344K), 0.0517700 secs] 147899K->10243K(1031552K), 0.0518839 secs] [Times: user=0.07 sys=0.00, real=0.05 secs]
2018-06-11T05:57:52.837+0000: 2.935: Total time for which application threads were stopped: 0.0521348 seconds, Stopping threads took: 0.0000305 seconds
2018-06-11T05:57:53.370+0000: 3.468: Total time for which application threads were stopped: 0.0129146 seconds, Stopping threads took: 0.0014676 seconds

I do not have enough knowledge to understand gc log, could you please give me some clue to these message? I am able to send log from (remote) Logstash to Elasticsearch and view by Kibana (Test by sending a MySQL log file from Logstash).

I want to confirm if these messages cause problem or I can ignore them. Or I will encounter issue when log traffic become huge (because I have only tested function with single log file)?

Thanks in advance for any comment,
Fiona

[danielmitterdorfer]

Hi,

these are GC log messages that help you to understand what the garbage collector of the Java virtual machine is doing. This is useful when doing garbage collector tuning but the presence of these log lines is nothing to worry about. If you're interested in more info, you can check Oracle's Garbage Collection Tuning Guide for example.

Daniel