Admin command "show @@backend" may list the connections which were closed already, coz the close functionality is asynchronous.

[wjl1619]

• dble version：
  5.6.29-dble-9.9.9.9-cd56a7b75b923309e6c401206b911ef59d1e4c58-20190708060610
• preconditions ：
  no
• configs：

schema.xml

rule.xml

server.xml

• steps：
  step1. execute with "show @@backend"
• expect result：
  1.The results should not contain the connections which were closed already.
• real result：
  1.The results may contain the connections which were closed already.
• supplements：
  1.

[yanhuqing666]

delay