Hi Any body please tell me , my application has 10 processes , all processes are connects to DB for getting customers details.and my DB wait_timeout value is 30 sec. what will happen when my application is sleep more than wait_timeout value ?
You will get MySQL server has gone away if wait_timeout exceeds.
I think you can use auto reconnect option in your application refer
http://dev.mysql.com/doc/refman/5.0/en/auto-reconnect.html
Related
I have a MySQL 5.7.16 running on a Centos 6. I read about these two configuration variables as,
interactive_timeout - interactive time out for mysql shell sessions in
seconds like mysqldump or mysql command line tools.
wait_timeout - the amount of seconds during inactivity that MySQL will
wait before it will close a connection on a non-interactive connection
in seconds.
I set both these variables to 120 seconds in my server which means that after this time, both interactive (mysql shell) and non-interactive (like front end applications) should have their connections get disconnected automatically, if they are in "sleep" mode.
I observed some sessions from the application and other TCP/IP connections from different IDEs like MySQL Workbench running even after 120 seconds. Sometimes they go more than 200 seconds.
Are there any other settings I need to do in my configuration file?
Did you set the GLOBAL variable to 120?
Use
SET GLOBAL wait_timeout = 120
insted
SET wait_timeout= 120
remember that value is refreshed only for new connections.
Run:
SELECT ##global.wait_timeout, ##session.wait_timeout;
to check the real value.
I am doing bulk inserting and getting error as Mysql2::Error: Lost connection to MySQL server during query:
I searched for this error on the Internet and most of the blogs/articles asking to increase net_read_timeout value.
I searched on the Internet about net_read_timeout but not getting any article/blog which describes it in easy to understandable language.
On MySQL website net_read_timeout is describe as "The number of seconds to wait for more data from a connection before aborting the read". I am totally confused with this statement and not getting it.
I also want to know about net_write_timeout and wait_timeout variable.
MySQL uses different timeout variables for various stages.
When connection is established it uses connection_timeout
When it waits for the next query it uses wait_timeout
When it doesn't receive the query in the specific time it uses net_read_timeout and net_write_timeout
And so on...
Usually net_read_timeout shouldn't be a problem but when you have some network trouble, especially when communicating with the server this timeout could be raised because instead of a single packet for the query, that you sent to the Database, MySQL waits for the entire query to be read but, due to the network problem, it doesn't receive the rest of the query. MySQL doesn't allow client to talk the server until the query result is fetched completely.
You cannot properly change those two variable, which are sessions variable after all.
Also from the MySQL Doc you can read
net_read_timeout:
The number of seconds to wait for more data from a connection before aborting the read. When the server is reading from the client, net_read_timeout is the timeout value controlling when to abort. When the server is writing to the client, net_write_timeout is the timeout value controlling when to abort. See also slave_net_timeout.
net_write_timeout:
The number of seconds to wait for a block to be written to a connection before aborting the write. See also net_read_timeout.
You can check the defaults variable within MySQL itself using
> mysql show variables like '%timeout';
I understood about wait_timeout settings. mysql default wait_timeout is 28800 seconds which 8 hours. now to understand how wait_timeout works execute following sql statement.
set wait_timeout = 10;
After executing above statement if mysql server has not received any sql statement withing 10 seconds then it will automatically close the connection.
To test it wait for 10 seconds and then execute any sql query it will give you error like "mysql closed connection during query execution"
will update my answer for net_read_timeout and net_write_timeout shortly.
This is happening when you are using the non-buffering connection to the mysql database, and after executing your query, you are not consuming the data.
client python connect with non-buffering SSDictCursor
connection = pymysql.connect(host='localhost',
user='xxxx',
password='xxxx',
db='employees',
charset='utf8mb4',
cursorclass=pymysql.cursors.SSDictCursor)
sql = " select * from employees"
cursor = connection.cursor()
cursor.execute(sql)
cursor.fetchone()
doing nothing and your connection will be timed out
or
if not fetching all data within 60 seconds(net_write_timeout), your connection will be aborted.
quote from doc:
When the server is writing to the client, net_write_timeout is the timeout value controlling when to abort
2019-08-14T15:20:26.465498Z 28440 Query select * from employees
2019-08-14T15:21:26.584634Z 28440 [Note] Aborted connection 28440 to db: 'employees' user: 'xxxx' host: 'localhost' (Got timeout writing communication packets)
MySQL by default is letting me have 151 simultaneous connections.
It let me increase it through MAX ALLOWED CONNECTIONS option in the Workbench.
When I have increased the count to 1000, it is not getting reflected.
The Server Status page shows that the Maximum Allowed Client connection is still set to 300.
Why is that ?
Is there a way that I can increase this count for say 10000 or even 1,00,000 ?
I have MySQL Server installation on Windows 7 PC.
Two ways to set:
1. set GLOBAL max_connections=XXX in command line
2. add max_connections=XXX in my.ini file and restart mysql
Max connection limit is 100000 in my Win7 PC.
To set it: SET max_connections=10000
To verify it: SHOW VARIABLES LIKE 'max_connections'
However, before setting this variable pls make sure you read How Mysql opens and closes tables section of mysql documentation to understand the implications and posdible limits your OS imposes!
When manually running an sql query from an app server, if a user just clicks the X to close the window instead of using F12 or the menu to close the connection to the DB, what kind of negative impact can there be?
.
Is there an automatic timeout for connections?
The timeout of a MySQL connection is defined in the /etc/my.cnf file in the wait_timeout server system variable. It's defaulted to 28800 (seconds) - we usually set it for our clients to a very low value - ranging from 10 seconds to 60 seconds. So, if you leave a connection unclosed, then it'll close, by default, after 28800 seconds (that's very high if you have a large number of clients using the app).
In your case, interactive_timeout doesn't apply, since you are not really using the console.
for some reason when I open a connection the the Percona MySQL database on my HostGator website, after fetching the query, it will disconnect/ close the connection about 10 seconds later.
I typically wouldn't care, but HeidiSQL freezes up, preventing exporting or sorting the returned rows with it's UI unless I connect again.
Any thoughts on making the connection last longer? is it something I can do myself, or will it require a dedicated server or some upgrade? (I'm currently on a shared one). Thanks!
Sounds like it may be the "wait" timeout on the MySQL connection.
SHOW VARIABLES LIKE 'wait_timeout'
That's the amount of time (in seconds) that MySQL will leave the session (the database connection) open while it's idle, waiting for another statement to be issued. After this amount of time expires, MySQL can close the connection.
You should be able to change this for a session, to change the timeout to 5 minutes
SET wait_timeout = 300
Verify the setting with the SHOW VARIABLES statement again.
NOTE: This is per connection. It only affects the current session. Every new connection will inherit their own wait_timeout value from the global setting.
(This is only a guess. There's insufficient information in the question to make a precise diagnosis. It could be something other than MySQL server that's closing the database connection, e.g. it could be your connection pool settings (if you are using a connection pool).