Hoping someone may be able to help me with a solution as to starting a background thread to monitor my database connection. Our application is deployed in weblogic 92 and I wondered if there was a way to start a thread running when the application is running ? thanks
I'm attempting to monitor my database to ensure I can switch databases should my connection fail. For this reason, I'm looking for an easy solution to run a background task.
Even though in many applications servers you can, you're not supposed to create your own threads in a Java EE server, see Why is spawning threads in Java EE container discouraged? for some background and workarounds.
Depending on what condition you want to check for and what action you want to take you can use the WebLogic Diagnostic Framework. You could have it send a JMS message when it detects a certain condition and then you can do whatever you want with an MDB.
Update your question with the condition & action you want to take and I can provide more details.
Generally speaking, starting your own threads isn't advisable.
UPDATE:
By your description I'm guessing you don't use JNDI or WebLogic datasources. It would be better if you used the datasources in WebLogic for connection pooling. WebLogic can detect that a connection in the pool is bad and recreate it before giving it to your application.
If you are referring to different databases then WebLogic has a multi-datasource option which has failover capability. What you should do is configure two datasources - one primary and one secondary - and then create a multi-datasource to wrap them. You then should use the JNDI of the multi-datasource in your application. Obviously if you do this you need to make sure the data is consistent between the two DB instances.
This does not make your application WebLogic-specific since it would just be a change to a JNDI name. WebLogic takes care of the rest.
Related
I have two legacy servers in GCE, which have both been flagged as using the deprecated metadata server endpoints. At this moment in time, they have hundreds of GB's of data between them in MySQL and MongoDB data, and risking upgrading something on these boxes which has an adverse affect is not an option.
We are currently in the process of migrating away from the data stored here, but for now, we need to keep them running.
Is anyone aware of any implications to either
a) doing nothing or
b) Just setting the disable-legacy-endpoints metadata flag to true ?
i.e. Will these instances stop working altogether if we leave them as they currently are?
After some more digging into what was actually using the Metadata API to start with, we found that they were being sent by stackdriver_agent which was installed an extremely long time ago while it was free, and just never removed.
Stopping this agent will remove all calls that we make with these two legacy servers.
If you are considering disabling with the disable-legacy-endpoints metadata flag, make sure to test it in a contained environment first, i.e. a new VM from a snapshot of the affected instance, before apply to production services.
For help identifying the instances making the calls, refer to this article
For help identifying the processes within the instances, refer to this article
We are developing a Web API using .Net Core. To perform background tasks we have used Hosted Services.
System has been hosted in AWS Beantalk Environment with the Load Balancer. So based on the load Beanstalk creates/remove new instances of the system.
Our problem is,
Since background services also runs inside the API, When load balancer increases the instances, number of background services also get increased and there is a possibility to execute same task multiple times. Ideally there should be only one instance of background services.
One way to tackle this is to stop executing background services when in a load balanced environment and have a dedicated non-load balanced single instance environment for background services only.
That is a bit ugly solution. So,
1) Is there a better solution for this?
2) Is there a way to identify the primary instance while in a load balanced environment? If so I can conditionally register Hosted services.
Any help is really appreciated.
Thanks
I am facing the same scenario and thinking of a way to implement a custom service architecture that can run normally on all of the instance but to take advantage of pub/sub broker and distributed memory service so those small services will contact each other and coordinate what's to be done. It's complicated to develop yes but a very robust solution IMO.
You'll "have to" use a distributed "lock" system. You'll have to use, for example, a distributed memory cache who put a lock when someone (a node of your cluster) is working on background. If another node is trying to do the same job, he'll be locked by the first lock if the work isn't done yet.
What i mean, if all your nodes doesn't have a "sync handler" you can't handle this kind of situation. It could be SQL app lock, distributed memory cache or other things ..
There is something called Mutex but even that won't control this in multi-instance environment. However, there are ways to control it to some level (may be even 100%). One way would be to keep a tracker in the database. e.g. if the job has to run daily, before starting your job in the background service you might wanna query the database if there is any entry for today, if not then you will insert an entry and start your job.
I need to modify the number of threads available in my Weblogic 10.0 MP2 environment for some perf benchmarking but I cannot seem to be able to find where exactly that option lies.
Can anyone share this info please? thank you.
Weblogic 10 does not use execute thread queues like in previous versions (i.e. Weblogic 8.1 and older)
This concept is now replaced with Work Managers.
These are self-tuned, i.e. WLS will auto-tune the number of threads every 2 seconds based on how it sees the need to increase threads for the application load.
You can confirm this from the console, it will show the increasing number of execute threads as the load increases.
You can use the work manager and constraints to make sure your applications get certain criteria met.
Such as certain web apps or EJBs can get a higher share of threads and so on.
For a quick read see http://www.oracle.com/technetwork/articles/entarch/workload-management-088692.html
and
http://m-button.blogspot.com/2009/02/tuning-default-workmanager-on-weblogic.html
Secondly, are you running in dev mode or production mode.
If dev mode, you can try this cmd line parameter
-Dweblogic.threadpool.MinPoolSize=100
but I am not sure if it will work, so it's better to leave it to Work Managers
I found this annswer:
1. Long answer to Quartz requiring to data sources, however, if you want an even deeper answer, I believe I’ll need to dig into the source code or do more research:
a. JobStoreCMT relies upon transactions being managed by the application which is using Quartz. A JTA transaction must be in progress before attempt to schedule (or unschedule) jobs/triggers. This allows the "work" of scheduling to be part of the applications "larger" transaction. JobStoreCMT actually requires the use of two datasources - one that has it's connection's transactions managed by the application server (via JTA) and one datasource that has connections that do not participate in global (JTA) transactions. JobStoreCMT is appropriate when applications are using JTA transactions (such as via EJB Session Beans) to perform their work. (Ref; http://quartz-scheduler.org/documentation/quartz-1.x/configuration/ConfigJobStoreCMT)
However, there is a believed conflict with a non transactional driver in our particular application. Does anyone know if Quartz (JobsStoreCMT) can just work with just a transactional data source?
Does anyone know if Quartz (JobsStoreCMT) can just work with just a transactional data source?
No you must have a datasource of each type. Invocations on the API by the client application use the connections that are XA-capable, so that the work join's the application's transaction. Work done by the scheduler's internal threads use the non-XA connections.
I am new to weblogic server. I am using work manager. I want to know what is work manager and why we need it. What is the difference between normal request with out work manager and with work manager !!
I think the documentation is rather good on this subject.
WebLogic Server prioritizes work and allocates threads based on an
execution model that takes into
account administrator-defined
parameters and actual run-time
performance and throughput.
Administrators can configure a set of
scheduling guidelines and associate
them with one or more applications, or
with particular application
components. For example, you can
associate one set of scheduling
guidelines for one application, and
another set of guidelines for other
application. At run-time, WebLogic
Server uses these guidelines to assign
pending work and enqueued requests to
execution threads.
Essentially, with work managers you can attach a scheduling policy to an application to e.g. make sure that a specific application gets a fair share of the available computing resources under a heavy load situation. Or you might want to restict the maximum number of threads that will be allocated to an application to prevent a buggy/untested application to bring the whole application server to its knees. (But surely all apps have been tested not to do anything like that.... ;) )
Outside of modifying the default allocation algorithms, the Work Manager is also useful if you are using a Foreign JMS Provider (such as IBM MQ) and need to process more than 16 messages at a time.