I have an application developed with Java using MySQL and C3P0 for connection pooling. The application works perfectly fine in localhost, the connection management was superb. However, I uploaded this application to Daily Razor "private JVM", and here we go, there were lot of MySQL connections than the application will ever make! Normally the application will make max 10 connections, but when I hosted there I can see 30 or more.
Apart from that, I always had number of mysql processors running in my localhost, but when uploaded to the online server I can only see 2. It is like upside down. The application works fine but there were number of times that I had to restart the server due to slow connection issue.
What is making this kind of thing? Anyway pls don't ask for code, because I don't know where the issue is
Related
I'm new to java and tomcat. I'm developing a website in java using spring mvc. It's deployed to a linux server that's running Tomcat 8. Everything works fine when I deploy, it connects to the database great. The issue is that the site seems to go idle very quickly. I haven't been able to time it exactly, but it seems like it only takes about a minute of inactivity for the entire site to go idle. Then the next request is extremely slow, loading in all my classes. I'm losing my sessions as well.
Is this a common occurrence? Does it sound like I'm doing something wrong in java? Tomcat? Both?
EDIT: In light of StuPointerException's comment, I've updated my database connection management. I'm now using Apache dbcp. I will update if this resolves the problem. I want to give my QA tester ample time to hit my site some more.
It's difficult to answer your question directly without more information about your server setup.
For what it's worth though, every time I see this kind of behaviour it's down to a mis-configured database connection pool. There can be a significant overhead in creating new database connections.
If you don't use a connection pool or you're allowing connections in the pool to die (due to missing validation queries/checks) then you will start to see performance problems over time due to connection timeouts.
I plan on making a distributed application where 10-15 computers are connected in a LAN and there is one server where the database will be stored, also inside the LAN.
For the purpose of the question lets say the application will be made using Java and the database will be MySQL, but that is not yet decided.
So the question is, what do I need to realize this?
I have ofcourse worked with MySQL databases, but on a single computer so I am not quite sure how to connect the computers to the database server. Is it enough to setup the server local IP on all client computers and connect to it using the JDBC MySQL driver, and after that I can work with it like the DB is on my machine?
Also, do I need a server application to manage connections to the database, so that there are no conflicting entries? And if I do, then the connection part changes, because it needs to be established over the server application, so how do I do that?
I know it is a large question, but a lot of things seem unclear, because I have never attempted a project this big.
Thank you all!
Don't worry just made your application, you can connect to your database via an #IP, so just make a part of configuration in your application to change some information in future:
String db_url = "jdbc:mysql://192.168.0.1/db_test";
Is it enough to setup the server local IP on all client computers and
connect to it using the JDBC MySQL driver, and after that I can work
with it like the DB is on my machine
You don't need a server local of every computer, you can connect to the server directly.
Also, do I need a server application to manage connections to the
database, so that there are no conflicting entries? And if I do, then
the connection part changes, because it needs to be established over
the server application, so how do I do that?
If you are using a desktop application, the you don't need a server application, else if you are using a web application, yes you need one.
You need to shouse a server application, this dippend of your project or your company, there are free servers like GlassFish, Payara, Apache Tomcat, Wildfly and more.
Now the connection to your database, there are many ways to connect to your database, if you are using JPA to connect to your database, then you will hear
something about Entities, Facades, JNDI so this generally be configure in your server
application.
Hope you get an idea.
I'm currently developing a Java Websocket application that is deployed on Wildfly 10. I cannot post the code, but here's the logic:
Multiple threads poll a database every 5 seconds(select query, reusing a PreparedStatement after closing previous ResultSet) and send via Websocket to all connected clients.
Have configured datasource that connects to MYSQL server (localhost).
The application runs fine until a while later, it crashes and the log is full with 'Unable to get managed connection from datasource' errors. Also, Websocket fails with 'ClosedChannelException'.
Services on the same server that open a connection and close it immediately do work fine. However there are 5-6 threads in the concerned code that must use connections after 5 secs so a thread is given a dedicated connection that is only torn down when the application context is destroyed.
Another thing is when the application fails, it works for a lesser time on disable-enable. Only a reboot gets it to work better.
Same project works without error on Glassfish.
Somehow, Wildfly seems to periodically reset either DB connections, or all TCP connections altogether.
Is there a setting that is relevant to Wildfly's behaviour towards threads? I have verified that only as many threads as are intended are actually created.
Any help would be appreciated.
Edit: This application works well on my local machine. When I deploy it on remote server, it works for a while (3 hours max) before failing altogether.
I use Netbeans 8 to compile, if that helps.
I know this sounds like a generic question, but I need some guidance.
We have a distributed system with Java swing client, Glassfish 3.0.1 as application server and PostgreSQL as database. We are using hessian protocol for communication with the Glassfish 3.0.1 server.
There are around 5 users using the client simultaneously. Everything is running fine, until all users say that their client stops responding for 10 seconds and then it continues to run fine for 15 minutes for example. And then the same thing happens. When I restart the server they say it is fine, but after half a day, again the same thing happens. I looked at the database logs, and I don't see queries above 1 second. I think the problem is connected with the communication to the Glassfish server(all clients cannot communicate to the server at the same time).
How could I approach the problem?
P.S When glassfish stops responding, I can't even open the index.html page properly.
Greetings,
Petar
First of all, we are running a Java Web application running on WAS 5.1. Behind that, we use an Oracle data base. The problem that we're faced to is really simple, but after a couple of hours of Google search, I decided to ask you.
We have an application that is running on WAS. When we start the server, WAS sets his DataSource so that it points to the data base. Everything works fine, expect when the DBAs have to reboot the data base server. When they do, the data source is no longer valid and we have to manually restart all server and we are currently trying to correct that, if possible. We need to find a way to do it because we have 3 pre-production environnement for for our application, and there are two servers associated with it, one for the application and the other is a report generator web service. So, when the DBAs wants to reboot the server (and they usually don't tell us!) we have to reboot six servers. I was wondering if in Java, there was a way to reset the data source so that we don't need to restart the servers.
For you information, WebSphere is v5.1 and Oracle is 9g with Java 1.4.2.17.
We also use RAD:
Version: 6.0.1
Build id: 20050725_1800
You should configure your application server to always test the connection before leasing it out to a client. I'm not familiar with Websphere that much, but in WebLogic, you can set a jdbc sql statement such as select 1 from dual and the container removes stale connections from the connection pool.
Here is a link on how to do it in Websphere
http://www-01.ibm.com/support/docview.wss?uid=swg21439688
Based on what i read from your note, you should receive Stale connection exception as WAS has stale handles (in its pool) as the DB has been restarted.
The Data Source configuration can be configured to purge the entire pool once a stale connection is detected. The default policy is to purge the individual connection.
Adopting this would prevent you from restarting your WAS Servers.
There are a number of resources in this space
http://www-01.ibm.com/support/docview.wss?uid=swg21063645
HTH
Manglu