First test in each test suite fails connecting to the DB

Question

We are running more than 2000 junit, Most of the tests connect to an Oracle database with jdbc calls. We have a problem with very few of the tests that can not connect to the DB for some reason. Here is some background:

• We are running the tests in a CI server - Jenkins
• Tests are being run by ANT with <junit> task with fork="true"
• Only few of the tests fail with Could not connect to database error, it's not consistent, sometimes they fail and sometimes not.
• The tests that fail are usually the first tests in each test suite
• The rest of the tests that also connect to the db do not fail.

So far we have no luck in solving it. Anyone encountered something similar ?

Here's a stack trace:

Error Message

Could not connect to database using the connect string jdbc:oracle:thin:R71/R71@abc.def:1521:DB11g
Stacktrace

java.lang.RuntimeException: Could not connect to database using the connect string jdbc:oracle:thin:R71/R71@abc.def:1521:DB11g
    at com.abc.common.dao.JDBCUtils.getThinConnection(JDBCUtils.java:257)
    at com.abc.common.dao.JDBCUtils.getConnection(JDBCUtils.java:115)
    at com.abc.common.dao.JDBCUtils.queryForInt(JDBCUtils.java:714)
    at com.abc.test.utils.MetaDataLanguageDBTest.testMetaDataLanguages(MetaDataLanguageDBTest.java:13)
Caused by: java.sql.SQLRecoverableException: IO Error: Connection reset
    at oracle.jdbc.driver.T4CConnection.logon(T4CConnection.java:428)
    at oracle.jdbc.driver.PhysicalConnection.<init>(PhysicalConnection.java:536)
    at oracle.jdbc.driver.T4CConnection.<init>(T4CConnection.java:228)
    at oracle.jdbc.driver.T4CDriverExtension.getConnection(T4CDriverExtension.java:32)
    at oracle.jdbc.driver.OracleDriver.connect(OracleDriver.java:521)
    at java.sql.DriverManager.getConnection(DriverManager.java:582)
    at java.sql.DriverManager.getConnection(DriverManager.java:207)
    at com.abc.common.dao.JDBCUtils.getThinConnection(JDBCUtils.java:254)
Caused by: java.net.SocketException: Connection reset
    at java.net.SocketOutputStream.socketWrite(SocketOutputStream.java:96)
    at java.net.SocketOutputStream.write(SocketOutputStream.java:136)
    at oracle.net.ns.DataPacket.send(DataPacket.java:199)
    at oracle.net.ns.NetOutputStream.flush(NetOutputStream.java:211)
    at oracle.net.ns.NetInputStream.getNextPacket(NetInputStream.java:227)
    at oracle.net.ns.NetInputStream.read(NetInputStream.java:175)
    at oracle.net.ns.NetInputStream.read(NetInputStream.java:100)
    at oracle.net.ns.NetInputStream.read(NetInputStream.java:85)
    at oracle.jdbc.driver.T4CSocketInputStreamWrapper.readNextPacket(T4CSocketInputStreamWrapper.java:123)
    at oracle.jdbc.driver.T4CSocketInputStreamWrapper.read(T4CSocketInputStreamWrapper.java:79)
    at oracle.jdbc.driver.T4CMAREngine.unmarshalUB1(T4CMAREngine.java:1122)
    at oracle.jdbc.driver.T4CMAREngine.unmarshalSB1(T4CMAREngine.java:1099)
    at oracle.jdbc.driver.T4CTTIfun.receive(T4CTTIfun.java:288)
    at oracle.jdbc.driver.T4CTTIfun.doRPC(T4CTTIfun.java:191)
    at oracle.jdbc.driver.T4CTTIoauthenticate.doOAUTH(T4CTTIoauthenticate.java:366)
    at oracle.jdbc.driver.T4CTTIoauthenticate.doOAUTH(T4CTTIoauthenticate.java:752)
    at oracle.jdbc.driver.T4CConnection.logon(T4CConnection.java:366)
Standard Error

java.sql.SQLRecoverableException: IO Error: Connection reset
    at oracle.jdbc.driver.T4CConnection.logon(T4CConnection.java:428)
    at oracle.jdbc.driver.PhysicalConnection.<init>(PhysicalConnection.java:536)
    at oracle.jdbc.driver.T4CConnection.<init>(T4CConnection.java:228)
    at oracle.jdbc.driver.T4CDriverExtension.getConnection(T4CDriverExtension.java:32)
    at oracle.jdbc.driver.OracleDriver.connect(OracleDriver.java:521)
    at java.sql.DriverManager.getConnection(DriverManager.java:582)
    at java.sql.DriverManager.getConnection(DriverManager.java:207)
    at com.abc.common.dao.JDBCUtils.getThinConnection(JDBCUtils.java:254)
    at com.abc.common.dao.JDBCUtils.getConnection(JDBCUtils.java:115)
    at com.abc.common.dao.JDBCUtils.queryForInt(JDBCUtils.java:714)
    at com.abc.test.utils.MetaDataLanguageDBTest.testMetaDataLanguages(MetaDataLanguageDBTest.java:13)
    at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
    at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:39)
    at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:25)
    at java.lang.reflect.Method.invoke(Method.java:597)
    at junit.framework.TestCase.runTest(TestCase.java:154)
    at junit.framework.TestCase.runBare(TestCase.java:127)
    at junit.framework.TestResult$1.protect(TestResult.java:106)
    at junit.framework.TestResult.runProtected(TestResult.java:124)
    at junit.framework.TestResult.run(TestResult.java:109)
    at junit.framework.TestCase.run(TestCase.java:118)
    at junit.framework.TestSuite.runTest(TestSuite.java:208)
    at junit.framework.TestSuite.run(TestSuite.java:203)
    at org.apache.tools.ant.taskdefs.optional.junit.JUnitTestRunner.run(JUnitTestRunner.java:421)
    at org.apache.tools.ant.taskdefs.optional.junit.JUnitTestRunner.launch(JUnitTestRunner.java:912)
    at org.apache.tools.ant.taskdefs.optional.junit.JUnitTestRunner.main(JUnitTestRunner.java:766)
Caused by: java.net.SocketException: Connection reset
    at java.net.SocketOutputStream.socketWrite(SocketOutputStream.java:96)
    at java.net.SocketOutputStream.write(SocketOutputStream.java:136)
    at oracle.net.ns.DataPacket.send(DataPacket.java:199)
    at oracle.net.ns.NetOutputStream.flush(NetOutputStream.java:211)
    at oracle.net.ns.NetInputStream.getNextPacket(NetInputStream.java:227)
    at oracle.net.ns.NetInputStream.read(NetInputStream.java:175)
    at oracle.net.ns.NetInputStream.read(NetInputStream.java:100)
    at oracle.net.ns.NetInputStream.read(NetInputStream.java:85)
    at oracle.jdbc.driver.T4CSocketInputStreamWrapper.readNextPacket(T4CSocketInputStreamWrapper.java:123)
    at oracle.jdbc.driver.T4CSocketInputStreamWrapper.read(T4CSocketInputStreamWrapper.java:79)
    at oracle.jdbc.driver.T4CMAREngine.unmarshalUB1(T4CMAREngine.java:1122)
    at oracle.jdbc.driver.T4CMAREngine.unmarshalSB1(T4CMAREngine.java:1099)
    at oracle.jdbc.driver.T4CTTIfun.receive(T4CTTIfun.java:288)
    at oracle.jdbc.driver.T4CTTIfun.doRPC(T4CTTIfun.java:191)
    at oracle.jdbc.driver.T4CTTIoauthenticate.doOAUTH(T4CTTIoauthenticate.java:366)
    at oracle.jdbc.driver.T4CTTIoauthenticate.doOAUTH(T4CTTIoauthenticate.java:752)
    at oracle.jdbc.driver.T4CConnection.logon(T4CConnection.java:366)
    ... 25 more

Thanks.

Answer 1

I know this question is super old, but I just had the same problem. The solution for me was to add the following environment variable to my tests:

-Djava.security.egd=file:///dev/urandom

In short, the Oracle JDBC driver uses /dev/random by default, which can block if there isn't enough entropy on the system. The full explanation can be found in this answer.

Answer 2

It could be that you are running out of connections. I would try using a DataSource backed by a connection pool instead.