CODEWITHSUNDEEP
mysqlgo
city
city

Reputation: 2154

what is the best solutions to mysql connection timeout?

I am writing a small web app in Go, which uses mysql to store data.

I got intermittent mysql error if the web sever didn't get any request after some amount of time(> 8 hours):

[mysql] 2017/02/08 16:31:56 packets.go:33: unexpected EOF
[mysql] 2017/02/08 16:31:56 packets.go:130: write tcp 127.0.0.1:49188->127.0.0.1:3306: write: broken pipe

I found some related discussion on github(issue 529, issue 257 and issue 446). From what I understand, mysql db would close the connection if timeout is reached.

I tried to set SetMaxOpenConns to 9 and SetMaxIdleConns to 0 as some people recommended. However, this threw exception immediately. (But if I set SetMaxIdleConns larger than 0, there was no immediate exception thrown)

I also tried to set SetConnMaxLifetime to 5 mins. This threw exception too after 5 mins.

Now I am trying the code below:

db.SetConnMaxLifetime(0)
db.SetMaxOpenConns(10)
db.SetMaxIdleConns(5)

It has been running for 20 mins. It's still too early to tell. (UPDATE: this doesn't work either)

Here is configuration:

Upvotes: 3

Views: 8731

Answers (2)

lupguo
lupguo

Reputation: 1641

  1. you can check your mysql time_wait variable:

    mysql> show global variables like 'wait_timeout':
+---------------+-------+
| Variable_name | Value |
+---------------+-------+
| wait_timeout  | 300   |
+---------------+-------+
1 row in set (0.00 sec)

  2. then use db.SetConnMaxLifetime(120*time.Second), which mean when db connection is idle over than 120s, sql.db will reopen or get a new connection from db pool by db.Open. If you not set connection max life time, you maybe use a closed connection and got the error.

  3. watching the mysql process list，mysql> show processlist;，if connection sleep over than 300s，it's recycled by mysql:

    mysql> show processlist;
+-------+-----------------+------------------+-------------+---------+---------+------------------------+------------------+
| Id    | User            | Host             | db          | Command | Time    | State                  | Info             |
+-------+-----------------+------------------+-------------+---------+---------+------------------------+------------------+
|     4 | event_scheduler | localhost        | NULL        | Daemon  | 1363480 | Waiting on empty queue | NULL             |
| 26539 | root            | 172.17.0.1:48732 | NULL        | Query   |       0 | starting               | show processlist |
| 26575 | auditcenter     | 172.17.0.1:51714 | obs_gb_test | Sleep   |      51 |                        | NULL             |
+-------+-----------------+------------------+-------------+---------+---------+------------------------+------------------+
3 rows in set (0.00 sec)

  4. SetMaxOpenConns and SetMaxIdleConns is used for setting connection resource, see enter link description here

Upvotes: 3

Joe
Joe

Reputation: 6610

Perhaps you can start a heartbeat Goroutine to avoid timeout.

Upvotes: 2

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