I have a running instance of VerneMQ (cluster of 2 nodes) on Google kubernets and using MySQL (CloudSQL) for Auth. Server accepts connections over TLS
It works fine, but after a few days i start seeing this message on the log:
can't authenticate client {[],<<"Client-id">>} from X.X.X.X:16609 due to plugin_chain_exhausted
The client app (paho) complains that the server refused the connection for being "not authorized (code=5 in paho error)"
after a few retry it finally connects. but every time it get's harder and harder until it just won't connect anymore
If i restart VerneMQ everything get's back to normal
I have only 3 clients currently connected at most, at the same time.
clients already connected have no issues in pub/sub.
In my configuration i have (among other things):
log.console.level=debug
plugins.vmq_diversity=on
vmq_diversity.mysql.* = all of them set
allow_anonymous=off
vmq_diversity.auth_mysql.enabled=on
it's like the server degrades over time. the status webpage reports no problem
My verne server was build from the git repository about a month ago and runs on a docker container
what could be the cause?
what else could i check to find posibles causes? maybe a diversity missconfiguration?
Tks
To quickly explain the plugin_chain_exhausted log: with Verne you can run multiple authentication/authorization plugins, and they will be checked in a chain. If one plugin allows the client, it will be in. If no plugin allows the client, you'll see the log above.
This does not explain the behaviour you describe, though. I don't think I have seen that.
In any case, the first thing to check is whether you actually run multiple plugins. For instance: have you disabled the vmq.passwd and the vmq.acl plugins?
Error displaying the error page: Application Instantiation Error: Could not connect to MySQL.
This Error is shown sometimes (one every 20 pageviews) and I tried a lot of solutions without any change.
This error found with Joomla 3.5+
This will help you do some testings...
On MySql server run this query...
show processlist;
If this shows a lot of connections then you may be hitting the max_connections problem. Try to increase that to a reasonable number. But, do not make it too much because if it goes beyond the amount of available resources on your server then it will make MySql server crash and it will become a bigger problem where your website will go offline.
Try to check if you are closing sessions properly in your scripts using session_write_close(); You can find more about this function here: http://php.net/manual/en/function.session-write-close.php
This function will write user's current session on disk to be reloaded next time and most important part it will do for you with this problem is that it will close PHP's any connection made to the MySql server, so it will free up the MySql server for next visitor to come and open another page.
Lets say if you have 150 max_connections and at the same time you get 200 visitors, then PHP will still wait for some time for another 50 connections to be free before giving a timeout error where you get "Could not connect to server". But, if sessions are not closing properly, then its so bad that 50 connections will never get processed because 150 will never go away very soon, there is a separate MySql setting for that named wait_timeout. So, any MySql connection you open will keep waiting until you close yourself in script just like you open OR until wait_timeout happens. But, if you close sessions properly then next connection will become available as soon as your PHP script has finished processing and page is generated for the user for viewing and it will make the connection seat free for next connection to come in.
Server RAM was very low!
After upgrade from 0.5GB to 2GB all the kind of error starts with Error displaying the error page: gone.
I found the problem solution by using htop while connecting to the server via SSH, after that, I start opening pages rapidly which show the error plus the htop shows that the RAM was close to full.
show processlist; were helpful to find that the problem not about the connection number.which it may sometimes cost the same error in the same way.
I am trying to hit 350 users but Jmeter failing script by saying Connection timed out.
I have added following:
http.connection.stalecheck$Boolean=true in hc.parameter file
httpclient4.retrycount=1
hc.parameter.file=hc.parameter
Is there anything that I am missing to add on?
This normally indicates a problem on application under test side so I would recommend checking the logs of your application for anything suspicious.
If everything seems to be fine there - check logs of your web and database servers, for instance Apache HTTP Server allows 150 connections by default, MySQL - 100, etc. so you may need to identify whether you are suffering from this form of limits and what needs to be done to raise them
And finally it may be simply lack of CPU or free RAM on application under test side so next time you run your test keep an eye on baseline OS health metrics as application may respond slowly or even hang if it doesn't have any spare headroom. You can use JMeter PerfMon plugin to integrate this form of monitoring with your load test.
I'm using Node.js to run a web-server for my web application. I'm also using the node-mysql module to interface with a MySQL server for all my persistent database needs.
Whenever there is a critical error within my Node.js application that crashes my app's process I get an email sent to me. So, I keep getting this email with an error saying "Too many connections". Here's an example of the error:
Error: Too many connections
at Function.Client._packetToUserObject (/apps/x/node_modules/mysql/lib/client.js:394:11)
at Client._handlePacket (/apps/x/node_modules/mysql/lib/client.js:307:43)
at Parser.EventEmitter.emit (events.js:96:17)
at Parser.write.emitPacket (/apps/x/node_modules/mysql/lib/parser.js:71:14)
at Parser.write (/apps/x/node_modules/mysql/lib/parser.js:576:7)
at Socket.EventEmitter.emit (events.js:96:17)
at TCP.onread (net.js:396:14)
As you can see all it tells me is that the error is coming from the mysql module, but it doesn't tell me where in my application code the issue is occurring.
My application opens a db connection anytime I need to run one or more queries. I immediately close the connection after all my queries and data has been collected. So, I don't understand how I could be exceeding the 151 max_connections limit.
Unless there is a place in my code where I forgot to call db.end() to close the connection, I don't see how my app would leak like this. Even if there was such a mistake, I wouldn't get these emails sent by the dozens. Yesterday, I received almost 100 emails with roughly the same error. How could this be happening? If my application had leaked and allocated connections over time, as soon as the first error occurred the app process would crash and all connections would be lost, preventing the app to crash again. Since I received ~100 emails, this means the app crashed ~100 times, and all within a short period of time. This could only mean that somewhere in my application a lot of connections where established in a short period of time, right?
How could I avoid this problem? This is very discouraging. All help is highly appreciated. Thanks
MySQL has a default MAX_CONNECTIONS = '100' not 151 unless you changed it. Also, in truth you have MAX_CONNECTIONS + 1. The plus 1 allows a root user to logon even after you have maxed out the conenctions in order to figure out what is actually being used. When your connections are maxed out try logging on as root and running the following command from MySQL.
mysql> SHOW FULL PROCESSLIST
Post the output of this command above. Once you actually know what is consuming your resources you can go about fixing it.It could easily be your code that is leaving open connections.
You should take a look at the follwoing documentation: Show Processlist
+1 for question. Investigations showed us that node-mysql opens the connections and doesn't close them. Because of that at one moment be reach the limit of max connections. The question is why node-mysql doesn't close the connections?
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I'm getting a SQL Server error:
A transport-level error has occurred
when receiving results from the
server. (provider: Shared Memory
Provider, error: 0 - The handle is
invalid.)
I'm running Sql Server 2008 SP1, Windows 2008 Standard 64 bit.
It's a .Net 4.0 web application. It happens when a request is made to the server. It's intermittent. Any idea how I can resolve it?
The database connection is closed by the database server. The connection remains valid in the connection pool of your app; as a result, when you pickup the shared connection string and try to execute it's not able to reach the database. If you are developing Visual Studio, simply close the temporary web server on your task bar.
If it happens in production, resetting your application pool for your web site should recycle the connection pool.
Try the following command on the command prompt:
netsh interface tcp set global autotuning=disabled
This turns off the auto scaling abilities of the network stack
I had the same problem. I restarted Visual Studio and that fixed the problem
Transport level errors are often linked to the connection to sql server being broken ... usually network.
Timeout Expired is usually thrown when a sql query takes too long to run.
So few options can be :
Check for the connection in VPN (if used) or any other tool
Restart IIS
Restart machine
Optimize sql queries.
For those not using IIS, I had this issue when debugging with Visual Studio 2010. I ended all of the debugger processes: WebDev.WebServer40.EXE which solved the issue.
All you need is to Stop the ASP.NET Development Server and run the project again
If you are connected to your database via Microsoft SQL Server Management, close all your connections and retry.
Had this error when connected to another Azure Database, and worked for me when closed it.
Still don't know why ..
Look at the MSDN blog which details out this error:
Removing Connections
The connection pooler removes a connection from the pool after it has
been idle for a long time, or if the pooler detects that the
connection with the server has been severed.
Note that a severed connection can be detected only after attempting
to communicate with the server. If a connection is found that is no
longer connected to the server, it is marked as invalid.
Invalid connections are removed from the connection pool only when
they are closed or reclaimed.
If a connection exists to a server that has disappeared, this
connection can be drawn from the pool even if the connection pooler
has not detected the severed connection and marked it as invalid.
This is the case because the overhead of checking that the connection
is still valid would eliminate the benefits of having a pooler by
causing another round trip to the server to occur.
When this occurs, the first attempt to use the connection will detect
that the connection has been severed, and an exception is thrown.
Basically what you are seeing is that exception in the last sentence.
A connection is taken from the connection pool, the application does
not know that the physical connection is gone, an attempt to use it is
done under the assumption that the physical connection is still there.
And you get your exception.
There are a few common reasons for this.
The server has been restarted, this will close the existing connections.
In this case, have a look at the SQL Server log, usually found at:
C:\Program Files\Microsoft SQL Server\\MSSQL\LOG
If the timestamp for startup is very recent, then we can suspect that
this is what caused the error. Try to correlate this timestamp with
the time of exception.
2009-04-16 11:32:15.62 Server Logging SQL Server messages in file
‘C:\Program Files\Microsoft SQL Server\MSSQL.1\MSSQL\LOG\ERRORLOG’.
Someone or something has killed the SPID that is being used.
Again, take a look in the SQL Server log. If you find a kill, try to
correlate this timestamp with the time of exception.
2009-04-16 11:34:09.57 spidXX Process ID XX was killed by
hostname xxxxx, host process ID XXXX.
There is a failover (in a mirror setup for example) again, take a look in the SQL Server log.
If there is a failover, try to correlate this timestamp with the time
of exception.
2009-04-16 11:35:12.93 spidXX The mirrored database “” is changing roles from “PRINCIPAL” to “MIRROR” due to
Failover.
Was getting this, always after about 5 minutes of operation. Investigated and found that a warning from e1iexpress always occurred before the failure. This apparently is an error having to do with certain TCP/IP adapters. But changing from WiFi to hardwired didn't affect it.
So tried Plan B and restarted Visual Studio. Then it worked fine.
On closer study I noticed that, when working correctly, the message The Thread '<No Name>' has exited with code 0 occurred at almost exactly the time the run crashed in previous attempts. Some Googling reveals that that message comes up when (among other things) the server is trimming the thread pool.
Presumably there was a bogus thread in the thread pool and every time the server attempted to "trim" it it took the app down.
You get this message when your script make SQL Service stopped for some reasons. so if you start SQL Service again perhaps your problem will be resolved.
I know this may not help everyone (who knows, maybe yes), but I had the same problem and after some time, we realized that the cause was something out of the code itself.
The computer trying to reach the server, was in another network, the connection could be established but then dropped.
The way we used to fix it, was to add a static route to the computer, allowing direct access to the server without passing thru the firewall.
route add –p YourServerNetwork mask NetworkMask Router
Sample:
route add –p 172.16.12.0 mask 255.255.255.0 192.168.11.2
I hope it helps someone, it's better to have this, at least as a clue, so if you face it, you know how to solve it.
I got the same error in Visual Studion 2012 development environment, stopped the IIS Express and rerun the application, it started working.
I had the same issue. I solved it, truncating the SQL Server LOG.
Check doing that, and then tell us, if this solution helped you.
For me the solution was totally different.
In my case I had an objectsource which required a datetimestamp parameter. Even though that ODS parameter ConvertEmptyStringToNull was true 1/1/0001 was being passed to SelectMethod. That in turn caused a sql datetime overflow exception when that datetime was passed to the sql server.
Added an additional check for datetime.year != 0001 and that solved it for me.
Weird that it would throw a transport level error and not a datetime overflow error.
Anyways..
In my case the "SQL Server" Server service stopped. When I restarted the service that enabled me to run the query and eliminate the error.
Its also a good idea to examine your query to find out why the query made this service stop
For me the answer is to upgrade the OS from 2008R2 to 2012R2, the solution of iisreset or restart apppool didn't work for me.
I also tried to turn of TCP Chimney Offload setting, but I didn't restart the server because it is a production server, which didn't work either.
We encountered this error recently between our business server and our database server.
The solution for us was to disable "IP Offloading" on the network interfaces.
Then the error went away.
One of the reason I found for this error is 'Packet Size=xxxxx' in connection string. if the value of xxxx is too large, we will see this error. Either remove this value and let SQL server handle it or keep it low, depending on the network capabilities.
It happened to me when I was trying to restore a SQL database and checked following Check Box in Options tab,
As it's a stand alone database server just closing down SSMS and reopening it solved the issue for me.
This occurs when the database is dropped and re-created some shared resources is still considering the database still exists, so when you re-run execute query to create tables in the database after it was re-created the error will not show again and Command(s) completed successfully. message will show instead of the error message Msg 233, Level 20, State 0, Line 0 A transport-level error has occurred when sending the request to the server. (provider: Shared Memory Provider, error: 0 - No process is on the other end of the pipe.).
Simply ignore this error when you are dropping and recreating databases and re-execute your DDL queries with no worries.
I faced the same issue recently, but i was not able to get answer in google.
So thought of sharing it here, so that it can help someone in future.
Error:
While executing query the query will provide few output then it will throw below error.
"Transport level error has occurred when receiving output from
server(TCP:provider,error:0- specified network name is no longer
available"
Solution:
Check the provider of that linked server
In that provider properties ,Enable "Allow inprocess" option for that particular provider to fix the issue.