How do I get the connections made with flyway to postgres to use keepalives ?
I've tried appending ?tcpKeepAlive=true to the URL, that doesn't seem to work. (the url output while using the cli seems to omit that this is part of the URL, trying to set it as a jdbc.property. only throws an error)
what am I missing ?
note: my migration works with psql over tcp to a remote host without issue, but flyways dies reporting the connection as closed after ~ 10 minutes.
Related
In my application, I have an issue where I receive the "MySQL server has gone away" error during a quite long-running transaction. I know this has already been asked a lot, but I tried my test to go through all possible causes.
The one thing that baffles me a lot, is this error message in the log of the MariaDB server:
[Warning] Aborted connection 6 to db: 'default' user: 'root' host: '10.0.0.18' (Got timeout reading communication packets)
This would explain why the client reports a broken connection, but this error occurs 10-15 minutes before the client reports the "MySQL server has gone away" error. In the meantime, the client is happily running insert statements without an issue. But as soon the client runs a select statement, the statement fails practically immediately.
I have already checked for these possible causes:
The server was running all the time
wait_timeout is set to 8 hours, which is way longer than the time the transaction needs to fail
max_allowed_packet is set to 512M which should be more than enough since the query is a very short select statement
The server does not run out of memory
I'm pretty sure the issue must be related to the "Got timeout reading communication packets" error from the MariaDB log. But I cannot wrap my head around why the client still can write data. And why this timeout occurs in the first place, since the wait_timeout is super high.
Some system information:
I'm running on MariaDB 10.5.1
The client uses python 3.6 and mysqlclient, which uses libmysql, is used for the database connection
I hope maybe some of you have an idea what I should look for, because this is really driving me nuts.
I am using Gremlin Java driver to connect to a local gremlin server.
Simple code flow
Creating client
Cluster cluster = Cluster.build().addContactPoint(<endp>).port(<port>).enableSsl(false).create()
Client client = cluster.connect();
Submit Script
client.submit("g.V().count()");
If when i submit the first time the Gremlin server is down, on subsequent retries after bringing back gremlin server, connection still fails to create.
Exception First attempt when Gremlin Server is down:
org.apache.tinkerpop.gremlin.driver.exception.NoHostAvailableException: All hosts are considered unavailable due to previous exceptions. Check the error log to find the actual reason
Exception After Gremlin server is brought back up:
tinkerpop.gremlin.driver.exception.NoHostAvailableException: All hosts are considered unavailable due to previous exceptions
One thing to note is i do not create client on retry just do
Submit Script
client.submit("g.V().count()");
It is quite possible that Gremlin server may go down anytime, how to recover in such circumstances. Fundamentally is
NoHostAvailableExceptio
recoverable?
Normally, the Client should attempt to reconnect to a host that is previously marked unavailable. By default, it should be retrying the host at 1 second intervals as governed by this configuration: connectionPool.reconnectInterval. In your case, however I think you've uncovered a bug where the reconnect attempts are not started because the Client was never able to reach the host in the first place. As of 3.4.11, you can only remedy this by recreating the Client as you noted in your comments. I've created an issue to track this problem here: TINKERPOP-2569
I have a setup where I use Flask-MQTT to connect my python Flask API to a Mosquitto broker. Whenever I run the Flask API with the development server all is well. But whenever I spin it up for production (using wsgi+nginx), the connection with Mosquitto is made, but everytime i try to publish something i get the following error:
Socket error on client <unknown>, disconnecting.
My app.ini has the processes configured to 1 (processes = 1)
My mosquitto.config has the allow_anonymous flag set to trye (allow_anonymous true)
I can't really seem to figure out what I'm doing wrong here...
Update:
So what i think is happening is that the Flask-uwsgi application is trying to connect to mosquitto more than once. There is a master process that connects with Mosquitto on initialize. Then there is a second process that is being used whenever input is given on the Flask app. I'm not sure, but I think Mosquitto only wants one connection at the time, therefor erroring on the second. So now i either need to:
A) Configure Mosquitto in a way that it accepts multiple connection from the same device
B) Configure Flask in a way that wil only use one single process (configuring processes = 1 is not enough, it will still spawn two processes)
99% of the time, a "Socket error on client <unknown>" is an authentication error. I don't know Flask, so I don't know where to point you at, but something in your code is either trying to pass a username/password that is not defined to Mosquitto, or its trying a TLS connection with an cert that Mosquitto doesn't like.
Alright, it turns I could've read that the whole multiple processes wouldn't work from the start at the official Flask-MQTT documentation. It sais right there in think letters:
Flask-MQTT is currently not suitable for the use with multiple worker
instances.
So I looked at my uwsgi app.ini file again closely and actually the answer is quite simple. I turned out i had a like in there master = true.. after I removed that it works like a charm.
I have CoreFTP configured for localhost and the next code:
JSch.setLogger(new MyJschLogger()); //class for console output
Session session = jsch.getSession("user", "localhost", 21);
Properties config = new Properties();
config.put("StrictHostKeyChecking", "no");
session.setConfig(config);
session.setPassword("password");
session.connect();
when program achieves connect(), two messages appear at console output:
INFO: Connecting to localhost port 21
INFO: Connection established
...and nothing more happens. After some minutes, connection is closed by foreign host exception appears.
Why?
Thanks for all!
Port 21 is the normal port for FTP. JSch is only an SSH client, with support for SFTP in the ChannelSFTP class. JSch knows nothing about FTP (and SFTP is unrelated to FTP, other than by name and that it allows similar things).
You need to setup your server to use the SSH protocol (usually on port 22, but you can use any port, as long as you use the same port on the client). See the documentation - I think you have to check the SSH check box.
Also, if your code is nothing more than what you posted, then nothing more than connecting will happen. To transfer files, you will need to open a ChannelSFTP, and issue the right commands (e.g. call one or more of the put/get methods).
I also faced the similar issue:
"ERROR 2016-04-27 15:05:16,489 [CollectionThreadPool-0] com.dell.supportassist.collector.cli.executor.SSHExecutor: com.jcraft.jsch.JSchException: connection is closed by foreign host"
In my case, channel was getting closed randomly. And when we are trying to re-connect the channel then it was not re-connecting and failing.
This was happening due to looping logic while connecting, so I tried to connect the session without channel by calling method connectWithoutOpenChannel instead of connectinternal(). This resolved my issue.
So, I used the example on http://www.jcraft.com/jsch/examples/Sftp.java and I was trying to connect to ftp.secureftp-test.com.
That destination is a valid testing SFTP server (as mentioned in secureftp-test dot com/). I confirmed it by connecting to the server through nautilus. I also made sure that the password on my program was correct as well.
But, when I run the program and it hits session.connect(), it just says "INFO: Connection established" then it becomes quiet for a minute then it return:
"com.jcraft.jsch.JSchException: connection is closed by foreign host"
I am pretty sure that it got stuck in the while loop of the library but I do not know why. I tried it against my local ftp server and it also had the same problem.
During the quiet moment, I can type. But pressing enter does not send anything to the server.
Has anyone heard or seen the same problem?
Okay, it seems that secureftp-test.com is NOT an sftp server. That is ftps server.
What I did instead was creating my own sftp:
http://wiki.vpslink.com/Configuring_vsftpd_for_secure_connections_(TLS/SSL/SFTP)
Then run the example code but making sure that I have these lines before doing session.connect:
String knownHostsFilename = "/home/yourname/.ssh/known_hosts";
jsch.setKnownHosts(knownHostsFilename);