1

I used to have several connection reset errors on startup of my application.
What are possible cause and how could I fix this? 

    ...
Caused by: java.net.SocketException: Connection reset
    at java.net.SocketOutputStream.socketWrite(SocketOutputStream.java:115) ~[?:1.8.0_121]
    at java.net.SocketOutputStream.write(SocketOutputStream.java:155) ~[?:1.8.0_121]
    at oracle.net.ns.DataPacket.send(DataPacket.java:209) ~[ojdbc7-12.1.0.2.jar:12.1.0.2.0]
    at oracle.net.ano.CryptoDataPacket.send(Unknown Source) ~[ojdbc7-12.1.0.2.jar:12.1.0.2.0]
    at oracle.net.ns.NetOutputStream.flush(NetOutputStream.java:215) ~[ojdbc7-12.1.0.2.jar:12.1.0.2.0]
    at oracle.net.ns.NetInputStream.getNextPacket(NetInputStream.java:302) ~[ojdbc7-12.1.0.2.jar:12.1.0.2.0]
    at oracle.net.ns.NetInputStream.read(NetInputStream.java:249) ~[ojdbc7-12.1.0.2.jar:12.1.0.2.0]
    at oracle.net.ns.NetInputStream.read(NetInputStream.java:171) ~[ojdbc7-12.1.0.2.jar:12.1.0.2.0]
    at oracle.net.ns.NetInputStream.read(NetInputStream.java:89) ~[ojdbc7-12.1.0.2.jar:12.1.0.2.0]
    at oracle.jdbc.driver.T4CSocketInputStreamWrapper.readNextPacket(T4CSocketInputStreamWrapper.java:123) ~[ojdbc7-12.1.0.2.jar:12.1.0.2.0]
    at oracle.jdbc.driver.T4CSocketInputStreamWrapper.read(T4CSocketInputStreamWrapper.java:79) ~[ojdbc7-12.1.0.2.jar:12.1.0.2.0]
    at oracle.jdbc.driver.T4CMAREngineStream.unmarshalUB1(T4CMAREngineStream.java:429) ~[ojdbc7-12.1.0.2.jar:12.1.0.2.0]
    at oracle.jdbc.driver.T4CTTIfun.receive(T4CTTIfun.java:397) ~[ojdbc7-12.1.0.2.jar:12.1.0.2.0]
    at oracle.jdbc.driver.T4CTTIfun.doRPC(T4CTTIfun.java:257) ~[ojdbc7-12.1.0.2.jar:12.1.0.2.0]
    at oracle.jdbc.driver.T4CTTIoauthenticate.doOAUTH(T4CTTIoauthenticate.java:437) ~[ojdbc7-12.1.0.2.jar:12.1.0.2.0]
    at oracle.jdbc.driver.T4CTTIoauthenticate.doOAUTH(T4CTTIoauthenticate.java:954) ~[ojdbc7-12.1.0.2.jar:12.1.0.2.0]
    at oracle.jdbc.driver.T4CConnection.logon(T4CConnection.java:639) ~[ojdbc7-12.1.0.2.jar:12.1.0.2.0]
    at oracle.jdbc.driver.PhysicalConnection.connect(PhysicalConnection.java:666) ~[ojdbc7-12.1.0.2.jar:12.1.0.2.0]
    at oracle.jdbc.driver.T4CDriverExtension.getConnection(T4CDriverExtension.java:32) ~[ojdbc7-12.1.0.2.jar:12.1.0.2.0]
    at oracle.jdbc.driver.OracleDriver.connect(OracleDriver.java:566) ~[ojdbc7-12.1.0.2.jar:12.1.0.2.0]
    at org.apache.tomcat.jdbc.pool.PooledConnection.connectUsingDriver(PooledConnection.java:310) ~[tomcat-jdbc-8.5.11.jar:?]
    at org.apache.tomcat.jdbc.pool.PooledConnection.connect(PooledConnection.java:203) ~[tomcat-jdbc-8.5.11.jar:?]
    at org.apache.tomcat.jdbc.pool.ConnectionPool.createConnection(ConnectionPool.java:732) ~[tomcat-jdbc-8.5.11.jar:?]
    at org.apache.tomcat.jdbc.pool.ConnectionPool.borrowConnection(ConnectionPool.java:664) ~[tomcat-jdbc-8.5.11.jar:?]
    at org.apache.tomcat.jdbc.pool.ConnectionPool.init(ConnectionPool.java:479) ~[tomcat-jdbc-8.5.11.jar:?]
    at org.apache.tomcat.jdbc.pool.ConnectionPool.<init>(ConnectionPool.java:154) ~[tomcat-jdbc-8.5.11.jar:?]
    at org.apache.tomcat.jdbc.pool.DataSourceProxy.pCreatePool(DataSourceProxy.java:118) ~[tomcat-jdbc-8.5.11.jar:?]
    at org.apache.tomcat.jdbc.pool.DataSourceProxy.createPool(DataSourceProxy.java:107) ~[tomcat-jdbc-8.5.11.jar:?]
    at org.apache.tomcat.jdbc.pool.DataSourceProxy.getConnection(DataSourceProxy.java:131) ~[tomcat-jdbc-8.5.11.jar:?]
    at org.springframework.jdbc.datasource.DataSourceUtils.doGetConnection(DataSourceUtils.java:111) ~[spring-jdbc-4.3.6.RELEASE.jar:4.3.6.RELEASE]
    at org.springframework.jdbc.datasource.DataSourceUtils.getConnection(DataSourceUtils.java:77) ~[spring-jdbc-4.3.6.RELEASE.jar:4.3.6.RELEASE]
    at org.springframework.jdbc.support.JdbcUtils.extractDatabaseMetaData(JdbcUtils.java:326) ~[spring-jdbc-4.3.6.RELEASE.jar:4.3.6.RELEASE]
    ... 61 more
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1 Answer 1

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Adding JVM system propery may help:

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

java.security.SecureRandom is a standard API provided by sun. Among various methods offered by this class void nextBytes(byte[]) is one. This method is used for generating random bytes. Oracle 11g JDBC drivers use this API to generate random number during login. Users using Linux have been encountering SQLException("Io exception: Connection reset").

The problem is two fold

  1. The JVM tries to list all the files in the /tmp (or alternate tmp directory set by -Djava.io.tmpdir) when SecureRandom.nextBytes(byte[]) is invoked. If the number of files is large the method takes a long time to respond and hence cause the server to timeout

  2. The method void nextBytes(byte[]) uses /dev/random on Linux and on some machines which lack the random number generating hardware the operation slows down to the extent of bringing the whole login process to a halt. Ultimately the the user encounters SQLException("Io exception: Connection reset")

Users upgrading to 11g can encounter this issue if the underlying OS is Linux which is running on a faulty hardware.

Cause The cause of this has not yet been determined exactly. It could either be a problem in your hardware or the fact that for some reason the software cannot read from dev/random

(source)

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In our case, Red Hat Enterprise Linux Server release 6.9 (Santiago) with jvm is 1.7.0_51 connecting oracle 12c had this issue. However on same environment, a data-source pointing to oracle 11g was working. Though this solution worked for us, but we are not sure if its oracle version is the issue. or whenever JVM tries to connect tow or more oracle & the higher version of oracle connection gets this issue. Any pointers in this direction will be helpful. Thanks

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