I am using root as username.
My program will refresh every 5 seconds.
What it does is, it query from mysql table and display the data.
Problem is, every after 5 seconds, the connection on mysql will append, reason that it will give an error of "TOO MUCH CONNECTIONS" when it reach the limit.
Is it possible to kill the previous connection since it is unused already?
Here is my code on opening a connection.
connectionPool = connectionPool.getConnectionPool("root", "*****", "");
This is normal behavior if you are using a connection pool. When your job is over be sure that you free the connection instance, or close all pool connections when your code execution is done.
When you are done with a connection, you need to close it. this will return a connection back to the pool.
Related
I'm looking into aborted connection -
2022-11-21T20:10:43.215738Z 640870 [Note] Aborted connection 640870 to db: '' user: '' host: '10.0.0.**' (Got timeout reading communication packets)
My understanding is that I need to figure out whether it is an interactive or not connection, and increase wait_timeout (or interactive_timeout) accordingly. If it has no effect, then I'll need to adjust net_read_timeout or net_write_timeout and see.
I'd like to ask:
Is there a meta table that I can query for the connection type
(interactive or not)?
There are how-to's on the internet on adjusting wait_timeout (or
interactive_timeout) and all of them have rebooting the database as
the last step. Is that really required? Given that immediate effect
is not required, the sessions are supposed to come and go, and new
sessions will pick up the new value (after the system value is set),
I suppose if there is a way to track how many connections are left
with the old values, then it will be ok?
Finally, can someone suggest any blog (strategy) on handling aborted
connection or adjusting the timeout values?
Thank you!
RDS MySQL version 5.7
There is only one client that sets the interactive flag by default: the mysql command-line client. All other client tools and connectors do not set this flag by default. You can choose to set the interactive flag, because it's a flag in the MySQL client API mysql_real_connect(). So you would know if you did it. In some connectors, you aren't calling the MySQL client API directly, and it isn't even an option to set this flag.
So for practical purposes, you can ignore the difference between wait_timeout and interactive_timeout, unless you're trying to tune the timeout of the mysql client in a shell window.
You should never need to restart the MySQL Server. The timeout means the client closed the session after there has been no activity for wait_timeout seconds. The default value is 28800, which is 8 hours.
The proper way of handling this in application code is to catch exceptions, reconnect if necessary, and then retry whatever query was interrupted.
Some connectors have an auto-reconnect option. Auto-reconnect does not automatically retry the query.
In many applications, you are borrowing a connection from a connection pool, and the connection pool manager is supposed to test the connection before returning it to the caller. For example running SELECT 1; is a common test. The action of testing the connection causes a reconnect if the connection was not used for 8 hours.
If you don't use a connection pool (for example if your client program is PHP, which doesn't support connection pools as far as I know), then your client opens a new connection on request, so naturally it can't be idle for 8 hours if it's a new connection. Then the connection is closed as the request finishes, and presumably this request lasts less than 8 hours.
So this comes up only if your client opens a long-lived MySQL connection that is inactive for periods of 8 hours or more. In such cases, it's your responsibility to test the connection and reopen it if necessary before running a query.
I have Django RestFrameWork application in which we are using sqlalchemy library for MySql connection.
engine = create_engine('mysql+mysqldb://username:password#hostaddress/'
'DBname', pool_recycle=1800,
connect_args={'connect_timeout': 1800}, pool_size=10, max_overflow=10, pool_pre_ping=True)
connection = engine.connect()
As the API usage increases the Mysql is creating new connections and count of threads_connected keeps growing. After reaching max value it is throwing Too many connections error. In show processList many process will be in sleep mode. If we restart the app all the connections will be reset. The following chart indicates no.of connections v/s time. How to fix this issue.
You must close connections after you've finished using them because if you don't, the connection stays open until the webserver closes it which might take a lot of time.
The best practice would be using a connection pool. Because opening and closing connections are too heavy and decreases performance. Even if you're using a connection pool you must let the connection go after you've used it.
I get the following error accessing to a MySql Database from Jdbc:
java.sql.SQLNonTransientConnectionException: Too many connections
At the same time I am monitoring my connections. I added a counter that counts any opening and closing. The error ouccurs when I get to 380 opened and closed connections within 3 minutes.
Is it possible that it takes some time for MySql to acutally close the connection so that there are still too many opened even though I have send a command to close them?
I am just assuming certain points that might be the reason.
MySql Connections are maintained by MySql Connection Manager so once connection is released Manager will decide to kill that thread or return it back to pool.
In some cases if MySql Resultset is not closed after retrieving data and connection has been close on that time sending it back to pool might have some latency issue.
These two are points that i think might cause that, but i am not sure if these are correct or not.
There could be other reasons that i am not knowing about.
Hope it gives you some idea.
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).
I am getting this error from a mysql database
error connecting: Timeout expired. The timeout period elapsed prior to obtaining a connection from the pool. This may have occurred because all pooled connections were in use and max pool size was reached.
I have a website and console application talking to the database but i certainly dont have 100 concurrent connections! I did a showprocesslist query and found about 10 connections with a command of SLEEP and time of about 16000 seconds. There wasn't 100 connections.
I am using subsonic data provider to talk to the database and i believe this closes database connections immediately and doesnt leave them hanging so this isn't the culprit.
I restarted mysql server and my console application that talks to the database and it seems to be working ok but naturally I can't have the either console/website application crashing like this. Looking at the error log this error seems to be coming up
Please could you advice on anything I can do to find out what is going on and how i can fix it
EDIT: I have looked into this more and it appears it is subsonic/mysql issue. I have tried the recommended fix in the link below by closing the connection in a finally block but nothing closes the connection...
Dim sp As StoredProcedure = SPs.GetLastGPSDataForAllVehicles(customerID)
Dim reader As IDataReader
Try
reader = sp.GetReader
MyBase.Load(reader)
Catch ex As Exception
Finally
reader.Dispose()
reader = Nothing
sp.Command.ToDbCommand().Connection.Close()
End Try
I have no idea how to force the connection to close.
thanks a lot