[Bug 1803628] Re: jtreg fails to run under openjdk-8 due to api incompatibility with openjdk-9 or later

[Łukasz Zemczak]

Hello Tiago, or anyone else affected,

Accepted jtreg into bionic-proposed. The package will build now and be
available at
https://launchpad.net/ubuntu/+source/jtreg/4.2-b13-1ubuntu0.1~18.04.1 in
a few hours, and then in the -proposed repository.

Please help us by testing this new package.  See
https://wiki.ubuntu.com/Testing/EnableProposed for documentation on how
to enable and use -proposed.  Your feedback will aid us getting this
update out to other Ubuntu users.

If this package fixes the bug for you, please add a comment to this bug,
mentioning the version of the package you tested and change the tag from
verification-needed-bionic to verification-done-bionic. If it does not
fix the bug for you, please add a comment stating that, and change the
tag to verification-failed-bionic. In either case, without details of
your testing we will not be able to proceed.

Further information regarding the verification process can be found at
https://wiki.ubuntu.com/QATeam/PerformingSRUVerification .  Thank you in
advance for helping!

N.B. The updated package will be released to -updates after the bug(s)
fixed by this package have been verified and the package has been in
-proposed for a minimum of 7 days.

** Changed in: jtreg (Ubuntu Bionic)
       Status: New => Fix Committed

** Tags added: verification-needed verification-needed-bionic

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https://bugs.launchpad.net/bugs/1803628

Title:
  jtreg fails to run under openjdk-8 due to api incompatibility with
  openjdk-9 or later

Status in jtreg package in Ubuntu:
  Fix Released
Status in jtreg source package in Bionic:
  Fix Committed
Status in jtreg source package in Cosmic:
  Fix Released
Status in jtreg package in Debian:
  Fix Released

Bug description:
  [Impact]
  openjdk-9 introduced a few api changes that result in runtime errors when trying to run the java classes under openjdk 8 (or earlier) even when -source/-target are properly set.

  The fix is to build such code using the new openjdk-9 flag "--release"
  instead of the "-source/-target" pair.

  When running Cosmic's jtreg 4.2-b13-1 with agentvm under openjdk-8 it will fail and output a few lines such as:
  stderr: Exception: java.lang.NoSuchMethodError thrown from the UncaughtExceptionHandler in thread "main"

  The java.lang.NoSuchMethodError is actually caused by
  "java.lang.NoSuchMethodError:
  java.nio.ByteBuffer.flip()Ljava/nio/ByteBuffer" which can be easily
  solved by building jtreg with the "--release 7" argument.

  This affects the openjdk-8 build in Cosmic as the jtreg testsuites are
  run as part of the build. We use the test results for checking
  regressions from an update.

  [Test Case]
  For this test case we need to create an empty TEST.ROOT file and a test class to satisfy jtreg requirements of a minimum test. jtreg must also be forced to use openjdk-8.

  $ sudo apt install openjdk-8-jdk jtreg
  $ touch TEST.ROOT
  $ cat > Hello.java << EOF
  /*
   * @test
   * @bug 2718282
   * @summary Hello test
   */

  public class Hello {
      public static void main(String [] args) throws Exception {
          if (true)
              System.out.println("Hello World!");
          else
              throw new Exception("??");
      }
  }
  EOF
  $ JT_JAVA=/usr/lib/jvm/java-8-openjdk-amd64/ jtreg -va -agentvm Hello.java
  [2018-11-15 23:42:34,720] Agent[0]: stderr:
  [2018-11-15 23:42:34,721] Agent[0]: stderr: Exception: java.lang.NoSuchMethodError thrown from the UncaughtExceptionHandler in thread "main"
  --------------------------------------------------
  TEST: Hello.java
  TEST JDK: /usr/lib/jvm/java-8-openjdk-amd64
  [snipped]
  Test results: error: 1
  Report written to /tmp/JTreport/html/report.html
  Results written to /tmp/JTwork
  Error: Some tests failed or other problems occurred.

  The expected response from jtreg does not contain the "stderr:" lines as in:
  $ JT_JAVA=/usr/lib/jvm/java-8-openjdk-amd64/ jtreg -va -agentvm Hello.java
  --------------------------------------------------
  TEST: Hello.java
  TEST JDK: /usr/lib/jvm/java-8-openjdk-amd64
  [snipped]
  Test results: passed: 1
  Report written to /tmp/JTreport/html/report.html
  Results written to /tmp/JTwork

  Alternatively one can also check that openjdk-lts is not affected by the change, it should output the same before and after the fix:
  $ sudo apt install openjdk-11-jdk
  $ JT_JAVA=/usr/lib/jvm/java-11-openjdk-amd64/ jtreg -va -agentvm Hello.java
  --------------------------------------------------
  TEST: Hello.java
  TEST JDK: /usr/lib/jvm/java-11-openjdk-amd64
  [snipped]
  Test results: passed: 1
  Report written to /tmp/JTreport/html/report.html
  Results written to /tmp/JTwork

  [Regression Potential]
  1. The --release argument is jdk9+ only, if jtreg is ever build with an older jdk it will FTBFS, so this change should only be backported on releases where the default-jdk is 9+.
  2. The --release N argument is equivalent to setting -source N/-target N/-bootclasspath <N bootclasspath>, which can cause issues if the compiled classes use APIs that have been removed or are considered internal. The current jtreg version does not rely on internal classes from jdk 8 (otherwise it would FTBFS) but if a later version does that it will probably FTBFS - note that this is very unlikely as it would mean that upstream decided to break building jtreg with newer jdks.

  [Other Info]
  See https://github.com/apache/felix/pull/114 for a good overview on the methods that changed on OpenJDK 9 and a better description on the cause. Note that they propose patching the methods to cast ByteBuffer to Buffer when calling the affected methods, but this can be easily prevented by using the --release argument instead.

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