I have two Java Web Applications running under Tomcat (6.0) and using the Tomcat & c3p0 connection pool as Tomcat Data-source.If I define two Resources (server.xml) for two different Oracle Connection and use c3p0 for connection pool as below which my we applications use, my questions are:
<Resource
name="jdbc/OracleDB"
auth="Container"
type="com.mchange.v2.c3p0.ComboPooledDataSource"
driverClass="oracle.jdbc.OracleDriver"
factory="xxx"
jdbcUrl="jdbc:oracle:thin:#(DESCRIPTION= (LOAD_BALANCE=on)(ADDRESS_LIST=(ADDRESS=(PROTOCOL=TCP)(HOST=xxx) (PORT=1521))(ADDRESS=(PROTOCOL=TCP)(HOST=xxx)(PORT=1521)))(CONNECT_DATA=(SERVICE_NAME=xxx)))"
maxPoolSize="10"
minPoolSize="0"
maxIdleTime="60"
maxConnectionAge="600"
acquireIncrement="1"
user="xxx="
password="xxx=" />
<Resource name="jdbc/xxx2DB"
auth="Container"
type="com.mchange.v2.c3p0.ComboPooledDataSource"
driverClass="oracle.jdbc.OracleDriver"
factory="xxx"
jdbcUrl="jdbc:oracle:thin:#xxx:1527:xxx"
maxPoolSize="10"
minPoolSize="0"
acquireIncrement="1"
maxIdleTime="60"
maxConnectionAge="600"
user="xxx"
password="xxx"
/>
Q1. Does the below in server.xml mean that two connection pools are existing in the Tomcat
memory to two different Oracle Instances?
Q2. Do I have to specify any configuration properties (ref:http://www.mchange.com/projects/c3p0/index.html#configuration_properties) , in my case I have a connection to an Oracle RAC instance and another to a single instance of Oracle. Should I take into account
any additional configuration properties in an enterprise environment ?
Q3. Are the below setting valid enough?
Q4. How do I enable c3p0 logging (i have only the jar in Tomcat lib and the above setting for now?
Any advice?
Thanks in advance.
A1: Yes.
A2: Not sure if I got the question right, but you should only specify those connection properties which defaults do not make sense to you. It's probably best to do this in the separate c3p0.properties file and specify which connection which property applies to. Answer to 'additional configuration properties' question requires to know the specifics of your environment. I would recommend looking at idle_test_period setting as these can typically have wrong defaults (make sure this matches relevant setting on the DB end).
A3: Yeah, this looks OK.
A4: You need to specify logging preferences in c3p0.properties or define them in dynamically as System properties. Refer to this chapter of the c3p0 manual.
A1: Yes
A2: Looks right at first glance. You need to be careful with RAC in case you would use distributed transactions - then I believe you would have to specify additional properties.
A3: Looks ok but depending on your task and estimated load I would play with maxIdleTime, acquireIncrement and maxPoolSize. For example with current settings after 60 seconds of inactivity your connection will be closed so next operation requesting connection after 60 seconds would incur penalty in waiting for new connection to open.
A4: http://www.mchange.com/projects/c3p0/index.html#configuring_logging
Advice:
There is a better connection pool from Tomcat 7, which could be used in Tomcat 6 as well. Consider it, especially if you need high performance
Consider connection testing so your application don't get (or get less frequently) exception when db connectivity goes down
It might be preferable to package connection pool and it's configuration within your application vs. in Tomcat. This way application WAR would be self contained so it could be just dropped into wabapps dir of tomcat.
Related
I have come across some datasource properties for Spring Boot, that are specified in the application.properties. I am having a hard time understanding the purpose of the datasource properties.
Also, I am not able to find the explanation of these properties here for datasource - https://docs.spring.io/spring-boot/docs/1.1.2.RELEASE/reference/html/common-application-properties.html and I am using Spring Boot version 1.
spring.datasource.test-while-idle=true
spring.datasource.initial-size=10
spring.datasource.min-idle=10
spring.datasource.time-between-eviction-runs-millis=300000
spring.datasource.validation-query=SELECT 1 from DUAL
spring.datasource.test-on-borrow=true
spring.datasource.test-on-connect=true
spring.datasource.validation-interval=300000
The properties are validation-interval and time-between-eviction-runs-millis. What is the difference between them? The latter runs to evict the dead connections. But what about validation-interval?
Difference between test-on-borrow and test-on-connect?
I can't seem to find the right place to see their documentation or their purpose, or I am looking at the wrong place.
Please advise.
Following explanation is based on my experience, for your reference.
spring.datasource.time-between-eviction-runs-millis means the time interval to recycle idle connection. It is usually used with spring.datasource.test-while-idle.
spring.datasource.min-evictable-idle-time-millis means the effective time of idle connection in connection pool.
spring.datasource.test-on-borrow means whether testing the connection while borrowing the connection from connection pool. And it may have some impact on the performance.
spring.datasource.test-on-connect means whether testing the connection while creating the connection.
I have a Spring Boot application (version 1.5.1.RELEASE) and I am using spring-boot-starter-data-jpa as a dependency to manage my database. I am using postgres as my database and configured it using the below properties.
spring.datasource.url=${POSTGRES_URL}
spring.datasource.username=${POSTGRES_USER}
Now when I run my tests which are almost 120, I get too many client already open error for abou 10 test cases while starting the test case itself and it fails.(remaining 100 test cases pass with success as they are able to get a connection to database)
First thing I did is increased my default postgres max connections count from 100 to 200 in the postgres server config file and my tests pass successfully after this change.
Now I investigated a bit and tried setting the parameters for connection pooling properties such as :
spring.datasource.tomcat.max-active=200
spring.datasource.tomcat.test-on-borrow=true
spring.datasource.tomcat.max-wait=10000
However these properties do not work and the tests fails again giving the same error as above. I tried reading from multiple different blogs and spring documentation for setting the connection pool properties but did not find what might be going wrong with me.
I also think that if I set the above property spring.datasource.tomcat.max-active to 100 connections it should work with the help of tomcat jdbc pooling as i think in current scenario it is trying to open a new connection to database for each test case and I am in a fear that this same scenario might happen when I deploy this code to production environment and a new connection will be opened to the database for each request.
Does anyone have faced this problem before or is there something wrong I am doing.
Thanks in advance for the help.
Try upgrading Spring boot version, 1.5.10-RELEASE is the current version.
Also, I found the connection pool properties for my application were not being applied when the property prefix tomcat was included. If you are still having issues try removing that.
i.e.
spring.datasource.tomcat.max-active=200
Becomes
spring.datasource.max-active=200
See https://artofcode.wordpress.com/2017/10/19/spring-boot-configuration-for-tomcats-pooling-data-source
Environment:
Tomcat 7
JNDI
Spring-MyBatis
No JTA - commons pooling only
Problem: Can't get the connection pooling to work as advertised. I can't find a single example of this that doesn't use a stand-alone Transaction manager or that doesn't put all the settings in the war, which makes JNDI pointless. I'm told that JTA is overkill for this application and that we should stick with commons pooling. That makes sense but I don't see a way to configure pooling, if we do it that way.
So... how do I configure connection pooling without putting the settings in the war file AND without using a stand-alone transaction manager? Can this be done without a full Java EE Application Server? We are just moving to Tomcat from another product which actually is full Java EE, so I am thinking this may be a Container vrs. Application server issue.
The weird part is that we can and have used JNDI but the pooling is definitely wrong.
Here is one example that probably works but why bother with JNDI if the settings are going to be in META-INF/context.xml?:
MyBatis JNDI Example
Even with context.xml, it's still a container level setting. But, it's a convenient way of deploying everything in a singe unit rather than having to create the connection pool before you deploy the WAR file.
JNDI is meant to keep your application configuration generic. If you take your WAR and deploy it in WebSphere, for example, it will ignore the context.xml file. But WebSphere will see that you have a JDNI resource-ref in your web.xml and walk you through creating the data source. Same idea as Tomcat, just a different way of doing it.
If you are 100% sure that this application will only run in Tomcat then you don't have to use JNDI. But, it will save you trouble later if you do move to another container.
Which JDBC connection pool library should I use for a new application project (not web application)?
Apache DBCP has enough unresolved issues which are pushed until 2.0 I think.
C3P0 development seems to be stopped.
And both of them looks relatively slow.
Proxool is dead.
DBPool has almost no community (at least I've found no public one - no forums, no mailing lists...)
Apache Tomcat Pool looks to be unusable without Tomcat
I've found SQL Datasources article at Oracle website, but it seems, that it can be applied only to applets running in containers like servlets and web services.
Should I choose BoneCP may be? I don't have any huge requirements. I just need a good and easy to use database connection pool, that is in active development. Library, whose author can respond to bug reports, answer some specific question etc.
BTW, actually, I'm using MySQL only. I've found, that MySQL driver supports DriverManager interface, but I'm unsure if it actually pools connections or not.
You've done good research. I'd say, go ahead with BoneCP. Some years ago I would have suggested c3p0, but it has currently some open and unresolved issues as well. Too bad, actually. The BoneCP author is by the way also active here at SO.
It is possible use Tomcat Connection Pool without Tomcat, it is just a couple of .jars that you can include to any software. I have successfully used Tomcat Connection Pool with Resin and Jetty application servers.
Another alternative is Vibur DBCP. This is a new, concurrent JDBC connection pool based on Java dynamic proxies. It is fast, has concise source code, supports fairness parameter, JDBC Statement caching, long running SQL queries logging, and many other features.
Vibur DBCP is available in the central Maven repo, the website shows the needed Maven dependency, various configuration examples (with Spring, Hibernate 3.x/4.x/5.x), and all configuration options.
Vibur DBCP requires Java 1.7.
Disclaimer: I'm the author of Vibur DBCP.
I know its too late for answer but I just found an interesting link which has given a broader scope to answer most your queries. But at the end HikariCP and BoneCP are much better than other options.
In WebSphere, if you code opens two concurrent database connections, you get an error of the form:
J2CA0086W: Shareable connection MCWrapper id 556e556e Managed connection WSRdbManagedConnectionImpl#52365236 State:STATE_TRAN_WRAPPER_INUSE
from resource jdbc/abc was used within a local transaction containment boundary.
Our framework allows us to do so (nested transactions which can be on a separate connection or multiple named transactions). I've seen lots of references to turning off some switch in WebSphere to turn on connection sharing but no details on how to set this flag. Can someone point me to the steps to achieve this?
Specifically, if you see this article: http://www-01.ibm.com/support/docview.wss?rs=180&context=SSEQTP&dc=DB520&dc=D600&dc=DB530&dc=D700&dc=DB500&dc=DB540&dc=DB510&dc=DB550&q1=j2ca0086w&uid=swg21121449&loc=en_US&cs=utf-8&lang=en
under "Resolving the problem" I want to know how to set the connection pool to be unshareable (assuming that indeed solves the problem).
What version of IBM WAS are you using? If you have WAS 8, go to
Resources-> JDC-> Datasources-> your datasources -> WebSphere Application Server properties -> Datasources no transactional.
Sorry for my english.
The message happens when dataSource.getConnection() is called twice in
a servlet. The datasource jdbc/oracle is lookup from local reference.
Call it once and reuse the connection or call con.close() before doing the 2nd getConnection()