[MXS-3322] High number of Hangups Created: 2020-12-05  Updated: 2021-08-02  Resolved: 2021-08-02

Status: Closed
Project: MariaDB MaxScale
Component/s: Core
Affects Version/s: 2.5.5
Fix Version/s: N/A

Type: Bug Priority: Major
Reporter: Alex Assignee: Unassigned
Resolution: Not a Bug Votes: 0
Labels: None
Environment:

Debian 10, Mariadb 10.4.14



 Description   

I'm observing large number of Hangups:

┌────────────────────────┬───────────┐
│ Id                     │ 0         │
├────────────────────────┼───────────┤
│ Accepts                │ 18581517  │
├────────────────────────┼───────────┤
│ Reads                  │ 620290482 │
├────────────────────────┼───────────┤
│ Writes                 │ 757271808 │
├────────────────────────┼───────────┤
│ Hangups                │ 19743222  │
├────────────────────────┼───────────┤
│ Errors                 │ 0         │
├────────────────────────┼───────────┤
│ Avg event queue length │ 1         │
├────────────────────────┼───────────┤
│ Max event queue length │ 607       │
├────────────────────────┼───────────┤
│ Max exec time          │ 2         │
├────────────────────────┼───────────┤
│ Max queue time         │ 5         │
├────────────────────────┼───────────┤
│ Current FDs            │ 1154      │
├────────────────────────┼───────────┤
│ Total FDs              │ 152142218 │
├────────────────────────┼───────────┤
│ Load (1s)              │ 33        │
├────────────────────────┼───────────┤
│ Load (1m)              │ 39        │
├────────────────────────┼───────────┤
│ Load (1h)              │ 34        │
├────────────────────────┼───────────┤
│ QC cache size          │ 10046142  │
├────────────────────────┼───────────┤
│ QC cache inserts       │ 5945      │
├────────────────────────┼───────────┤
│ QC cache hits          │ 131887633 │
├────────────────────────┼───────────┤
│ QC cache misses        │ 5945      │
├────────────────────────┼───────────┤
│ QC cache evictions     │ 0         │
└────────────────────────┴───────────┘

Is it normal?



 Comments   
Comment by markus makela [ 2020-12-07 ]
  • How long has this particular MaxScale instance been in use?
  • Do you see any errors in the MaxScale log?
  • Does this cause errors to appear in either the application or database server logs?
Comment by Alex [ 2020-12-09 ]
  • 24 hours
  • Nothing special
  • No errors
Comment by markus makela [ 2021-08-02 ]

I think this might be normal as the end of a MariaDB session involves a COM_QUIT which triggers the server to close the connection. This closing of the connection should manifest as a hangup from the epoll point of view.

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