I am about to upgrade the JDK version from Java 1.6.0_37-b06 to Java 1.7.0_11.64 in a few hundreds of production servers, which run Tomcat servlets. The upgrade is a part of a large system upgrade from RHEL 5 to RHEL 6.

The upgrade will be tested on a staging environment on virtual machines before production deployment.

Are there any known Backward-compatibility issues between these two versions?

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  • What OS? What version? – schaiba Jan 30 '13 at 13:49
  • RHEL - updated my question. – Adam Matan Jan 30 '13 at 13:50
  • 1
    Here be dragons. – Tom O'Connor Jan 30 '13 at 13:59

I can't comment on the codebase running within Tomcat but we're running Tomcat 6 with Java 7 and there are no issues; the developers, however, need to conduct their own readiness tests. There a few housekeeping items to consider though such as

  • Custom certificates in the keystore that need to be transferred to the new JDK
  • Custom entries in the java.policy file? E.g. JMX options
  • Custom entries in java.security e.g. we adjust the DNS TTL in this file

Configuration management tools like Chef/Puppet can assist in this regard.

  • Thanks. I'm using a in-house configuration management tool, and my chief concern is software package compatibility. – Adam Matan Jan 30 '13 at 14:12

I've never had issues with Java 6 to Java 7... I typically did the move via the OpenJDK packaging to make sure /etc/alternatives and all symlinks were updated properly. You're going to have a much bigger issue with the mechanics of the EL5 to EL6 move, though.

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