Migrating from cassandra-driver-core(3.4.0) to java-driver-core (4.14.1) don't find an alternative to PoolingOptions class in new version, does anybody has implemented the same earlier or any suggestions?
Java driver is now driven by the configuration file - you can override default configurations with your own stuff either with additional config file, or programmatically (see manual). For pools there is a separate section called pool under datastax-java-driver.advanced.connection (source) where you can customize size of the pool, number of inflight requests, etc.
Related
There are 4 instances of an application running behind a load balancer. How the ConfigCat webhook would work in this case? Do we need to configure 4 public URL's for all 4 servers in webhook settings?
Could you share some details about your use case? What would you like to achieve with webhooks? What kind of SDK are you using? What is the polling mode?
If you want to refresh the SDK's cache on Feature Flag value changes, you should consider using a distributed cache implementation (e.g. redis). Example custom cache in Java: https://configcat.com/docs/sdk-reference/java#custom-cache
If you implement a custom distributed cache, you'll only need to add your load balancer's url to the webhook because refreshing the cache in one instance will refresh the cache in the distributed cache so all of your instances could work with the latest configurations.
If you want to get notified about changes in each applications, there are different possibilities:
You can configure 4 public urls and use the webhooks just like you mentioned it.
If you are using auto polling mode, you can skip the webhooks part and start using the SDK's built-in configuration changed callbacks. e.g. in java: configurationChangeListener part at https://configcat.com/docs/sdk-reference/java#auto-polling-default. When the auto poll mode's polling happens the SDK detects if the configuration changed and it fires this event.
If you could share more details I could help you more.
Disclaimer: I am one of the founders of ConfigCat.
In the wildfly config file (standalone.xml), it is possible to enable statistics for the ejb and datasources susbsystems
I would like to enable them to get useful infos at runtime (invocations, execution times,...)
But is it something that can be activated on a production server ?
Is there any overhead ?
The answer to both question is yes :) you can activate it and there will be an overhead.
You can use the jboss-cli to enable/disable the stats without requiring a restart of the server.
Is it possible to use https://github.com/prometheus/jmx_exporter on multiple targets or i need to run multiple instance of the jmx exporter ?
I'am using run_sample_httpserver.sh script.
You have to run one instance per target, as this keeps the responsibility of scheduling and service discovery with Prometheus. It's also recommended to use the java agent.
This worked for me you can check once may if of any help, just that it needed multiple config files to be created.Link
I have gone through the solution provided by peter for setting system properties dynamically in multithreading with the below link
System.setProperty used by a thread impacts other thread in communication to external network elements. How to resolve it?
But the problem is, tomcat is not considering the system properties that i am setting. So how to achieve this ?
I have mutiple threads in a management station connecting to different servers through RMI APIs and download the stub accordingly.
I am referring to the same name jar file as a stub at different locations for each server.
note: jar versions may differ at each location.
Eg: MS --> serv1 --> stublocation (http://15.xx.xx.xx:port/myfolder/myapp.jar)
MS --> serv2 --> stublocation (http://15.yy.yy.yy:port/myfolder/myapp.jar)
I want to set java.rmi.server.codebase system property for each of these locations dynamically and make it threadLocal so that it will not override each other settings.
With the example provided in the above link, I hope to achieve the solution for above problem.
But to test the resolution, i am unable to set these properties in tomcat.
Tomcat is ignoring the system properties that i am setting. Tomcat is considering the JVM arguments that are set through catalina.bat or service.bat but not through the system.properties as i need it to be dynamically set.
Any help here will be great! Thanks.
The java.rmi.server.codebase property is set at the JVM which exports remote objects. Setting it in a client JVM accomplishes exactly nothing, unless that JVM exports remote objects too, i.e. callbacks. It doesn't seem likely that you will be dealing with multiple versions of your own application within the same JVM.
In short, your question doesn't make sense.
As EJP points out, (successfully) setting that property is unlikely to achieve what you want.
But there are a couple of other important misconceptions in your question.
Tomcat doesn't implement RMI. RMI is actually implemented by the Java SE itself. Therefore, it is not up to Tomcat to pay attention to those property settings.
Typical Java services that use system properties for configuration purposes do it once during the lifetime of the JVM. Typically this happens when the relevant subsystem (e.g. RMI) initializes. The problem with setting system properties programmatically ("dynamically") is ensuring that they are set before the relevant initialization code uses them.
Going back to what you are trying to achieve, it seems that it is the same as or similar to this:
Java custom classloading and RMI
Nobody was able to help that person, and he ended up solving his problem another way. (I think he is saying that he handled serialVerionId mismatches with customized readObject / writeObject methods ...)
But his Q&A offers one possible way to solve the problem. It is a bit complicated.
The RMI system allows you to provide your own classloader for RMI to use. You do this by implementing the RMIClassLoaderSpi API and then registering your providers as described in the RMIClassLoader javadoc. That's one part of the equation.
The problem is that the RMI classloader is global, but you want RMI on different threads to use different class loaders.
Solution: delegate!
You implement your custom RMI classloader to delegate to one of a number of different classloaders, depending on which versions of the remote APIs that the context requires.
Since you have proposed using thread locals, you can declare a thread local variable for use by the custom RMI classloader, and have it use that variable's value to decide which classloader to delegate to.
CAVEAT ... I have not tried this!
I am using client - server mode of Hazelcast. Is it possible to control the logging level of Hazelcast server dynamically from Hazelcast client ?. My intention is that, by default I will start Hazelcast server in ERROR mode and in case of any problem, I want to change the log level to DEBUG mode without restarting the Hazelcast server.
Thanks
JK
Hazelcast does not depend on any custom logging frameworks and makes use of adaptors to connect to a number of existing logging frameworks. See some details here:
http://docs.hazelcast.org/docs/3.5/manual/html/logging.html
Most of the current logging frameworks allow you to dynamically / programmatically change the log levels. I'm at a loss here, since you haven't given any details of the logging framework you have used.
For example :
LogManager.getLogger("loggername").setLevel(newLoglevel);
will achieve whatever you are looking for. You can also change logj configuration file (logj.xml) in runtime and the changes will be in effect without restarting any of the hazelcast servers.