[ZOOKEEPER-3211] zookeeper standalone mode，found a high level bug in kernel of centos7.0 ，zookeeper Server's tcp/ip socket connections(default 60 ) are CLOSE_WAIT ，this lead to zk can't work for client any more

• Type: Bug
• Status: Open
• Priority: Major
• Resolution: Unresolved
• Affects Version/s: 3.4.5
• Fix Version/s: 3.4.5
• Component/s: server

Environment

1.zoo.cfg
server.1=127.0.0.1:2902:2903
2.kernel
kernel：Linux localhost.localdomain 3.10.0-123.el7.x86_64 #1 SMP Tue Feb 12 19:44:50 EST 2019 x86_64 x86_64 x86_64 GNU/Linux
JDK：
java version "1.7.0_181"
OpenJDK Runtime Environment (rhel-2.6.14.5.el7-x86_64 u181-b00)
OpenJDK 64-Bit Server VM (build 24.181-b00, mixed mode)
zk: 3.4.5

• Assignee: Unassigned
• Reporter: yeshuangshuang
• Created: 11/Dec/18 03:53
• Updated: 06/Jan/21 11:00

Description

1.config--zoo.cfg
server.1=127.0.0.1:2902:2903
2.kernel version
version：Linux localhost.localdomain 3.10.0-123.el7.x86_64 #1 SMP Tue Feb 12 19:44:50 EST 2019 x86_64 x86_64 x86_64 GNU/Linux
JDK：
java version "1.7.0_181"
OpenJDK Runtime Environment (rhel-2.6.14.5.el7-x86_64 u181-b00)
OpenJDK 64-Bit Server VM (build 24.181-b00, mixed mode)
zk: 3.4.5
3.bug details：
Occasionally，But the recurrence probability is extremely high. At first, the read-write timeout takes about 6s, and after a few minutes, all connections (including long ones) will be CLOSE_WAIT state.

4.:Circumvention scheme: it is found that all connections become close_wait to restart the zookeeper server side actively