i have an App with node js for web service connected to oracle 11g. The front end is react. The problem is that periodically,once in a month or two months, oracle collapses by many opened sessions came from my node web service. I am a new programmer, and i am worried if i could change sth to my node code, in order to kill sessions, or the Dba has to manage it.
I tried to monitor when sessions are highly opened, but it is more randomly that i thought. Also my app works 24/7. Also, i checked all connections to db and i found that all are being closed after connected. So how sessions remain opened and many times they multiplate and oracle collapses..
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We have a Node.js web application that connects to an Oracle DB instance, The problem is after some inactivity, connections of the database is turned to read-only mode. It means SELECT operations work but INSERT and UPDATE transactions encounter this error:
"Error: ORA-03114: not connected to ORACLE"
This problem solves after restarting the application. We use the last version of knex(0.20.1) and node-oracledb(4.1.0) library to connect to the database.
The error means that something (probably a firewall) has expired a connection. You should track down the cause and eliminate it. There may be work arounds such as configuring the Oracle Net layer to send occasional pings across the network to stop idle connections from being terminated, see https://oracle.github.io/node-oracledb/doc/api.html#connectionha
Both queries and DMLs will be equally affected on the connection that gives the error - all will fail. I suspect you are using a different (new) connection for the query.
If you are using 19c client libraries (which, by the way, connect to Oracle DB 11.2 or later), then your connection string could use Easy Connect syntax like:
"mydbmachine.example.com/orclpdb1?expire_time=2"
This will perform a keep alive operation on idle connections, sending probes every two minutes. The general recommendation is to set the period to just less than half the time that connections will be terminated (e.g. by a firewall). See the tech article Oracle Database 19c Easy Connect Plus Configurable Database Connection
Syntax.
Other syntaxes can be used in older versions, or in tnsnames.ora files; check the doc.
I have faced same problem and found the solution.
Add environment variables (system variables)
ORACLE_HOME=installation path in my case F:\app\krushna\product\11.2.0\dbhome_1
and ORACLE_SID= orcl or xe .
Which ever you have.
It worked for me.
I have a node.js app that is intended to be running all the time. Is a core process that does some specific work for each of our clients.
Today, that app is feed with the clients data by a config (json) file on startup, every time we need to add/remove a client or change a client data, we edit the json and kill/restart the app.
I came with the idea of building another node.js app that should work as a cli to send instructions to the main app, I don't know where to start, is there a solution already for this?
I tought of using sockets to connect the app with the cli, but I feel it overkill.
What's the propper way of controlling a node.js app from another node.js app?
I know this question may be vague and leaves space for discussions and opinions, but I don't know where to start looking for, all my searches give me express.js or forever/pm2 articles.
You could try storing your data in a REDIS DB and subscribing to changes from the node applications. So, you could update the redis and the configuration changes trigger automatically from within node application
See this question
Another method is to emit global events from your CLI and have your apps listen to and update their code as required.
I have a web page project developed in MEAN stack instanced in a server with Docker.
I have 2 container running, one has the API and the service, the other runs the mongodb service. Everything seems right but I have one big problem, in certain periods of time, the system drops my databases.
The last issue was on 11/03/2018 and the previous one 2 week ago.
These are the mongodb container last logs:
There is any configuration that maybe I can edit, or do you have passed through this problem?
If you need more information please do ask. Thanks.
Your database gets accessed from an external (public) IP. Your MongoDB server is publicly accessible and you have no authentication activated.
This official doc describes how you can enable authentication: https://docs.mongodb.com/manual/tutorial/enable-authentication/
Furthermore: You can restrict access to the server. If your app server and your mongodb server are in the same network, you need not to expose your mongodb to the public.
What are the circumstances to kill pomelo app itself?
The issue I am facing is that, the pomelo kills its own application without throwing any exception. When I try to run command 'pomelo list', it shows no server is running. The app gets close after few hours of running and automatically as well. I have gone through logs generated by pomelo on each server but there were no exception or blockage for the app.
Below are the details that might help you guys:
We are using distributed server structure of pomelo framework
MongoDB on different server
Redis instance on master-server itself
Pomelo version 1.2.1
We are also running same architecture for our different multi-player games but haven't gone through such issues ever. Can anybody explain why it might be happening? If you need any other info then please ask for the same.
This may be a basic question, but how do I go about effeciently deploying updates to currently running node.js code?
I'm coming from a PHP, JavaScript (client-side) background, where I can just overwrite files when they need updating and the changes are instantly available on the produciton site.
But in node.js I have to overwrite the existing files, then shut-down and the re-launch the application. Should I be worried by potential downtime in this? To me it seems like a more risky approach than the PHP (scripting) way. Unless I have a server cluster, where I can take down one server at a time for updates.
What kind of strategies are available for this?
In my case it's pretty much:
svn up; monit restart node
This Node server is acting as a comet server with long polling clients, so clients just reconnect like they normally would. The first thing the Node server does is grab the current state info from the database, so everything is running smoothly in no time.
I don't think this is really any riskier than doing an svn up to update a bunch of PHP files. If anything it's a little bit safer. When you're updating a big php project, there's a chance (if it's a high traffic site it's basically a 100% chance) that you could be getting requests over the web server while you're still updating. This means that you would be running updated and out-of-date code in the same request. At least with the Node approach, you can update everything and restart the Node server and know that all your code is up to date.
I wouldn't worry too much about downtime, you should be able to keep this so short that chances are no one will notice (kill the process and re-launch it in a bash script or something if you want to keep it to a fraction of a second).
Of more concern however is that many Node applications keep a lot of state information in memory which you're going to lose when you restart it. For example if you were running a chat application it might not remember who users were talking to or what channels/rooms they were in. Dealing with this is more of a design issue though, and very application specific.
If your node.js application 'can't skip a beat' meaning it is under continuous bombardment of incoming requests, you just simply cant afford that downtime of a quick restart (even with nodemon). I think in some cases you simply want a seamless restart of your node.js apps.
To do this I use naught: https://github.com/superjoe30/naught
Zero downtime deployment for your Node.js server using builtin cluster API
Some of the cloud hosting providers Node.js (like NodeJitsu or Windows Azure) keep both versions of your site on disk on separate directories and just redirect the traffic from one version to the new version once the new version has been fully deployed.
This is usually a built-in feature of Platform as a Service (PaaS) providers. However, if you are managing your servers you'll need to build something to allow for traffic to go from one version to the next once the new one has been fully deployed.
An advantage of this approach is that then rollbacks are easy since the previous version remains on the site intact.