Problem I am facing is, I am not using fluentd instance running on my local server.
I am just pushing some data through Java code by connecting to remote fluentd.
Example:
FluentLogger LOG = FluentLogger.getLogger(app, FLUENTD_ADDRESS, FLUENTD_PORT);
I connect to remote fluentd like this.
and just pushing some data using map.
This way I am connected to only one fluentd remote instance.
what if it fails to connect due to network failure. my messages are lost. Funny thing about it I wanted to catch exception if connection is not established. I am not able to catch exception if connection not established cause Java compiler doesnt understand it.
It's just displaying in the console couldn't connect but its not going to catch block.
If you see connection statement above, from LOG there is noway I can see if connection is open or not example there is LOG.open() I want to write my logs back to file incase connection failure but I don;t find such way to do that.
Can you please share your ideas on this.
Thanks in advance.
Possible solutions if you need high availability configurations
if you can install a local fluentd instance, you can use the forward type and this plugin can forward the log to multiple fluentd for HA.
use a software load balancer (TCP or HTTP)
Reference: http://docs.fluentd.org/articles/high-availability
Related
I have a web application running on an App Service on Azure cloud.
On the back-end I'm using a tcp connection to our database (Neo4j graph db), the best practice is to open the tcp connection and keep it alive in order to be more reactive when we perform queries.
The issue I encountered is that the database is logging the exception "Connection reset by peer";
reading on the web I found out that maybe Azure has a TCP timeout configured by default, I read it to be set up to 4 minutes, which could be my issue root cause.
Someone knows how to configure the tcp KEEP ALIVE to always for App Services on Azure?
I found on the web how to do it in Google cloud but nothing about Azure cloud.
Thank you in advance.
OaicStef
From everything I can find that is not an adjustable setting. Here is the forum link that says it will not be changing and that is a couple years old at this point. https://social.msdn.microsoft.com/Forums/en-US/32b76114-67a4-4e6b-ac45-61b0f0a0829f/changing-the-4-minute-request-time-out-for-app-services?forum=windowsazurewebsitespreview
I think you are going to have to add logic to your app that tests the connection, if it has been closed then either reopen it or create a new one. I don't know what language you are using to make any suggestions there.
Edit
I will add that the total number of TCP connections that can be open on a single App Service is about 6k, at least on the S1. Keep that in mind because if you don't have pooling on the server side or you are not disposing of those then you will exhaust that the TCP pool and you will start getting errors. I recommend you configure an alert for that.
We have a requirement for our project to listen to queues hosted in different machines. For example, we have 4 virtual hosts. I have created new instance of SimpleMessageListenerContainer for each hosts but i use one instance of MessageListener(it implements ChannelAwareListener so that i can manually ack). MessageListener is a bean managed by spring. I maintain a map of host and container instance when i create the containers. On receiving the message, check if i received the desired message from the host, get the container instance from the map (using #Resource) and stop listening to the host. Also manually ACK and store the message in the cassandra database.
Right now, there are times when some of the messages dont get persisted in the database and gets lost. I think it might be a race condition or due to the fact that i am using only one instance of messagelistener but i had to do that so that i can get the map(#Resource). Sorry if I am not making any sense. I am using the AMQP for the first time and trying to understand it. Any suggestions will be great. Thank you!
Why do you need manual ack? It's generally better to let the container take care of acks (AUTO). It will ack the message on success and nack it if the listener throws an exception.
I create a queue connection factory in Websphere using WebSphere MQ messaging provider.
Using JNDI to get this resource, and try to create queue connection in the same host.
The first time, everything works, but When I will to second time , it will throw a JMS Exception:
javax.jms.JMSException: Failed to create queue connection
at com.ibm.ejs.jms.JMSCMUtils.mapToJMSException(JMSCMUtils.java:141)
at com.ibm.ejs.jms.JMSQueueConnectionFactoryHandle.createQueueConnection(
JMSQueueConnectionFactoryHandle.java:90)
There is SO little information in the post it is hard to do anything but guess. First thing I'd look for is if the application or queue are set for exclusive use. Of course this assumes that you are opening the queue for input and that detail isn't mentioned in the question. Having the linked exception which would provide the actual WMQ reason and completion codes could tell you for sure but these also are not provided in the question.
Many shops consider it a Sev-1 defect if JMS code does not print linked exceptions. This is not a WMQ-specific thing but rather a case of printing out all the diagnostic information available regardless of the transport provider. In case you want more info on this, please see the WMQ Ifocenter JMS exception handling topic.
The Max Connection is there in WAS console. if connection getting more than Max connection and not release the resource (QueueConnection, QueueSender and QueueSession) than at the time of next connection it will fail to get the connection from connection pool. After restarting the Server only you can release the connection. this can be resolve by close all the resource(QueueConnection, QueueSender and QueueSession) properly in code.
How can I detect if a machine is connected/available in the present network.
It has several uses of course, but my main concern here is that my application uses resources located in specific machines and if they are not available it will not even attempt the connection and will use local resources.
you can try making a ping to the machine. check this article Making a PING with Delphi and the WMI.
ICMP echo request (PING) will tell you if the machine is up and reachable on the network. It will not tell you if the service you want to connect to is available on the machine (up and running).
Best bet would probably be to just attempt the connection and fall back to local resources if the connection fails.
Just try to use the resource and if you get an error use the local resource instead. The strategy you are trying to implement suffers from several problems including timing windows between the test and the use, during which the resource may become unavailable, and also doesn't actually test the resource for availability, only some lower-order thing like a TCP port or the ICMP echo part of the stack. In general the best way to detect whether a resource is available is just to try to use it, and recover from the failures. You have to write code to handle those failures anyway, why do it all twice?
A different strategy than trying to connect: let the server tell the clients if the services are still available, by sending UDP Broadcast or some kind of heartbeat signal over middleware (pipes?), which the clients listens to - a publish/subscribe communication model.
I have created a Datasnap service, using Bob Swart's white paper as a guide. I have been debugging and deployed succesfully using the VCL Forms application as a server. But when I try to deploy the service version, it installs ok, I then try to start the service and it immediately stops. The error in the event log would suggest that the port set is already in use, I have tried different port numbers for both the TCPServerTransport and the HTTPService without any joy. The DSServer is not set to Autostart as I want to set the Port number from a configuration file. The error message displayed in the event log is:
Service failed on start: Could not bind socket. Address and port are already in use..
I have also tried writing to a log file on start up and execute but it looks as if it is not getting this far.
Solution needed asap, before I have to revert back to a thick client which I do not really want to do.
Thanks
Firstly get a copy of TCPView from the Sysinternals suite (now run by Microsoft) and use it to monitor which app is using the port you want to use.
I would hazard a guess that if the app works fine as a stand alone (as you say it does) and you are trying to use the same port in the service then perhaps the service app is opening up the port at startup without you realizing it and then when you try to open the port manually the app finds it already in use. Or somehow the app is trying to open the port twice. The first time is successful but, maybe due to an event or an unexpected code path, the app tries to open it a second time and fails. TCPView will help spot this.
If you are sure that the port you have configured is actually free and not in use by any other software on the machine, then there might be some anti-virus / security software running that is blocking all software from listening on either specific ports or on any port except a few configured ones. The message you are getting could be one of the symptoms of how the anti-virus / security software handles attempts by apps to start listening on a port.