One CLOSE_WAIT connection remains every mod_cluster MCMP STATUS request in JBoss EAP 6.x/7.x

Solution Unverified - Updated -

Issue

  • mod_cluster DefaultMCMPHandler leaves one CLOSE_WAIT connection per each httpd/mod_cluster instance every MCMP STATUS request in JBoss EAP 6.x/7.x.

  • Anytime I checked nestat -tunapl command on JBoss machine, JBoss EAP CLOSE_WAIT holds one connection per each httpd/mod_cluster instance. It looks a CLOSE_WAIT connection remains 10 seconds and another new CLOSE_WAIT connection remains after the previous CLOSE_WAIT connection disappears:

Raw
$ while true; do date; sudo netstat -tunapl|grep <JBOSS_JAVA_PID>; echo "-----------"; echo ""; sleep 5; done
Tue Apr 17 14:39:53 JST 2018
tcp        0      0 127.0.0.1:9999          0.0.0.0:*               LISTEN      27379/java
tcp        0      0 127.0.0.1:8080          0.0.0.0:*               LISTEN      27379/java
tcp        0      0 127.0.0.1:4447          0.0.0.0:*               LISTEN      27379/java
tcp        0      0 127.0.0.1:9990          0.0.0.0:*               LISTEN      27379/java
tcp        0      0 127.0.0.1:8009          0.0.0.0:*               LISTEN      27379/java
tcp        0      0 127.0.0.1:8009          127.0.0.1:47152         ESTABLISHED 27379/java
tcp        0      0 127.0.0.1:8009          127.0.0.1:47166         ESTABLISHED 27379/java
tcp        0      0 127.0.0.1:8009          127.0.0.1:47148         ESTABLISHED 27379/java
tcp        0      0 127.0.0.1:8009          127.0.0.1:47136         ESTABLISHED 27379/java
tcp        0      0 127.0.0.1:8009          127.0.0.1:47142         ESTABLISHED 27379/java
tcp        0      0 127.0.0.1:8009          127.0.0.1:47158         ESTABLISHED 27379/java
tcp        0      0 127.0.0.1:8009          127.0.0.1:47172         ESTABLISHED 27379/java
tcp        1      0 127.0.0.1:38974         127.0.0.1:6666          CLOSE_WAIT  27379/java          // <-- !!
tcp        0      0 127.0.0.1:8009          127.0.0.1:47138         ESTABLISHED 27379/java
-----------

Tue Apr 17 14:39:58 JST 2018
tcp        0      0 127.0.0.1:9999          0.0.0.0:*               LISTEN      27379/java
tcp        0      0 127.0.0.1:8080          0.0.0.0:*               LISTEN      27379/java
tcp        0      0 127.0.0.1:4447          0.0.0.0:*               LISTEN      27379/java
tcp        0      0 127.0.0.1:9990          0.0.0.0:*               LISTEN      27379/java
tcp        0      0 127.0.0.1:8009          0.0.0.0:*               LISTEN      27379/java
tcp        0      0 127.0.0.1:8009          127.0.0.1:47152         ESTABLISHED 27379/java
tcp        0      0 127.0.0.1:8009          127.0.0.1:47166         ESTABLISHED 27379/java
tcp        0      0 127.0.0.1:8009          127.0.0.1:47148         ESTABLISHED 27379/java
tcp        0      0 127.0.0.1:8009          127.0.0.1:47136         ESTABLISHED 27379/java
tcp        0      0 127.0.0.1:8009          127.0.0.1:47142         ESTABLISHED 27379/java
tcp        0      0 127.0.0.1:8009          127.0.0.1:47158         ESTABLISHED 27379/java
tcp        0      0 127.0.0.1:8009          127.0.0.1:47172         ESTABLISHED 27379/java
tcp        1      0 127.0.0.1:38974         127.0.0.1:6666          CLOSE_WAIT  27379/java          // <-- !!
tcp        0      0 127.0.0.1:8009          127.0.0.1:47138         ESTABLISHED 27379/java
-----------

Tue Apr 17 14:40:03 JST 2018
tcp        0      0 127.0.0.1:9999          0.0.0.0:*               LISTEN      27379/java
tcp        0      0 127.0.0.1:8080          0.0.0.0:*               LISTEN      27379/java
tcp        0      0 127.0.0.1:4447          0.0.0.0:*               LISTEN      27379/java
tcp        0      0 127.0.0.1:9990          0.0.0.0:*               LISTEN      27379/java
tcp        0      0 127.0.0.1:8009          0.0.0.0:*               LISTEN      27379/java
tcp        1      0 127.0.0.1:38990         127.0.0.1:6666          CLOSE_WAIT  27379/java          // <-- !!
tcp        0      0 127.0.0.1:8009          127.0.0.1:47152         ESTABLISHED 27379/java
tcp        0      0 127.0.0.1:8009          127.0.0.1:47166         ESTABLISHED 27379/java
tcp        0      0 127.0.0.1:8009          127.0.0.1:47148         ESTABLISHED 27379/java
tcp        0      0 127.0.0.1:8009          127.0.0.1:47136         ESTABLISHED 27379/java
tcp        0      0 127.0.0.1:8009          127.0.0.1:47142         ESTABLISHED 27379/java
tcp        0      0 127.0.0.1:8009          127.0.0.1:47158         ESTABLISHED 27379/java
tcp        0      0 127.0.0.1:8009          127.0.0.1:47172         ESTABLISHED 27379/java
tcp        0      0 127.0.0.1:8009          127.0.0.1:47138         ESTABLISHED 27379/java
-----------

Tue Apr 17 14:40:09 JST 2018
tcp        0      0 127.0.0.1:9999          0.0.0.0:*               LISTEN      27379/java
tcp        0      0 127.0.0.1:8080          0.0.0.0:*               LISTEN      27379/java
tcp        0      0 127.0.0.1:4447          0.0.0.0:*               LISTEN      27379/java
tcp        0      0 127.0.0.1:9990          0.0.0.0:*               LISTEN      27379/java
tcp        0      0 127.0.0.1:8009          0.0.0.0:*               LISTEN      27379/java
tcp        1      0 127.0.0.1:38990         127.0.0.1:6666          CLOSE_WAIT  27379/java          // <-- !!
tcp        0      0 127.0.0.1:8009          127.0.0.1:47152         ESTABLISHED 27379/java
tcp        0      0 127.0.0.1:8009          127.0.0.1:47166         ESTABLISHED 27379/java
tcp        0      0 127.0.0.1:8009          127.0.0.1:47148         ESTABLISHED 27379/java
tcp        0      0 127.0.0.1:8009          127.0.0.1:47136         ESTABLISHED 27379/java
tcp        0      0 127.0.0.1:8009          127.0.0.1:47142         ESTABLISHED 27379/java
tcp        0      0 127.0.0.1:8009          127.0.0.1:47158         ESTABLISHED 27379/java
tcp        0      0 127.0.0.1:8009          127.0.0.1:47172         ESTABLISHED 27379/java
tcp        0      0 127.0.0.1:8009          127.0.0.1:47138         ESTABLISHED 27379/java
-----------

Tue Apr 17 14:40:14 JST 2018
tcp        0      0 127.0.0.1:9999          0.0.0.0:*               LISTEN      27379/java
tcp        0      0 127.0.0.1:8080          0.0.0.0:*               LISTEN      27379/java
tcp        0      0 127.0.0.1:4447          0.0.0.0:*               LISTEN      27379/java
tcp        0      0 127.0.0.1:9990          0.0.0.0:*               LISTEN      27379/java
tcp        0      0 127.0.0.1:8009          0.0.0.0:*               LISTEN      27379/java
tcp        1      0 127.0.0.1:38996         127.0.0.1:6666          CLOSE_WAIT  27379/java          // <-- !!
tcp        0      0 127.0.0.1:8009          127.0.0.1:47152         ESTABLISHED 27379/java
tcp        0      0 127.0.0.1:8009          127.0.0.1:47166         ESTABLISHED 27379/java
tcp        0      0 127.0.0.1:8009          127.0.0.1:47148         ESTABLISHED 27379/java
tcp        0      0 127.0.0.1:8009          127.0.0.1:47136         ESTABLISHED 27379/java
tcp        0      0 127.0.0.1:8009          127.0.0.1:47142         ESTABLISHED 27379/java
tcp        0      0 127.0.0.1:8009          127.0.0.1:47158         ESTABLISHED 27379/java
tcp        0      0 127.0.0.1:8009          127.0.0.1:47172         ESTABLISHED 27379/java
tcp        0      0 127.0.0.1:8009          127.0.0.1:47138         ESTABLISHED 27379/java
-----------

Environment

  • Red Hat JBoss Enterprise Application Platform (EAP) 6.x, 7.x
  • mod_cluster

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