Installing and using Red Hat build of OpenJDK 21 on RHEL

Procedure

1. Run the yum command, specifying the package you want to install:

   $ sudo yum install java-21-openjdk

2. Check that the installation works:

   $ java -version

   Note

   If the output from the previous command shows that you have a different major version of Red Hat build of OpenJDK checked out on your system, you can enter the following command in your CLI to switch your system to use Red Hat build of OpenJDK 21:

   $ sudo update-alternatives --config 'java'

Procedure

1. Create a directory to where you want to download the archive file, and then navigate to that directory on your command-line interface (CLI). For example:

   $ mkdir ~/jres
   
   $ cd ~/jres

2. Navigate to the Software Downloads page on the Red Hat Customer Portal.
3. Select the latest version of Red Hat build of OpenJDK 21 from the Version drop-down list, and then download the JRE archive for Linux to your local system.

4. Extract the contents of the archive to a directory of your choice.

   For example:

   $ tar -xf archive_file_name.tar.gz -C ~/jres

5. Create a generic path by using symbolic links to your JRE for easier upgrades:

   $ ln -s ~/jres/archive_file_name ~/jres/java-21

6. Configure the JAVA_HOME environment variable:

   $ export JAVA_HOME=~/jres/java-21

7. Verify that JAVA_HOME environment variable is set correctly:

   $ printenv | grep JAVA_HOME
   JAVA_HOME=~/jres/java-21

   Note

   When installed using this method, Java will only be available for the current user.

8. Add the bin directory of the generic JRE path to the PATH environment variable:

   $ export PATH="$JAVA_HOME/bin:$PATH"

9. Verify that java -version works without supplying the full path:

   $ java -version

   Note

   You can ensure that JAVA_HOME environment variable persists for the current user by exporting the environment variable in ~/.bashrc.

Procedure

1. Run the yum command, specifying the package you want to install:

   $ sudo yum install java-21-openjdk-devel

2. Check that the installation works:

   $ javac -version
   
   javac 21.0.1

Procedure

1. Create a directory to where you want to download the archive file, and then navigate to that directory on your command-line interface (CLI). For example:

   $ mkdir ~/jdks
   
   $ cd ~/jdks

2. Navigate to the Software Downloads page on the Red Hat Customer Portal.
3. Select the latest version of Red Hat build of OpenJDK 21 from the Version drop-down list, and then download the JDK archive for Linux to your local system.

4. Extract the contents of the archive to a directory of your choice:

   $ tar -xf archive_file_name.tar.xz -C ~/jdks

5. Create a generic path by using symbolic links to your JDK for easier upgrades:

   $ ln -s ~/jdks/archive_file_name ~/jdks/java-21

6. Configure the JAVA_HOME environment variable:

   $ export JAVA_HOME=~/jdks/java-21

7. Verify that JAVA_HOME environment variable is set correctly:

   $ printenv | grep JAVA_HOME
   JAVA_HOME=~/jdks/java-21

   Note

   When installed using this method, Java will only be available for the current user.

8. Add the bin directory of the generic JRE path to the PATH environment variable:

   $ export PATH="$JAVA_HOME/bin:$PATH"

9. Verify that java -version works without supplying the full path:

   $ java -version

Procedure

1. Run the following yum commands to install the package:

   For Red Hat build of OpenJDK 21

   $ sudo yum install java-21-openjdk

   For Red Hat build of OpenJDK 17

   $ sudo yum install java-17-openjdk

   For Red Hat build of OpenJDK 11

   $ sudo yum install java-11-openjdk

   For Red Hat build of OpenJDK 8

   $ sudo yum install java-1.8.0-openjdk

2. After installing, check the available Java versions:

   $ sudo yum list installed "java*"

3. Check the current java version:

   $ java -version

   Note

   You can install multiple major versions of Red Hat build of OpenJDK on your local system. If you need to switch from one major version to another major version, issue the following command in your command-line interface (CLI) and then follow the onscreen prompts:

   $ sudo update-alternatives --config 'java'

Procedure

1. To install the debug symbols, enter the following command:

   $ sudo debuginfo-install java-21-openjdk
   
   $ sudo debuginfo-install java-21-openjdk-headless

   These commands install java-21-openjdk-debuginfo, java-21-openjdk-headless-debuginfo, and additional packages that provide debug symbols for Red Hat build of OpenJDK 21 binaries. These packages are not self-sufficient and do not contain executable binaries.

   Note

   The debuginfo-install is provided by the yum-utils package.

2. To verify that the debug symbols are installed, enter the following command:

   $ gdb which java
   
   Reading symbols from /usr/bin/java...Reading symbols from /usr/lib/debug/usr/lib/jvm/java-21-version/bin/java-21-version.x86_64.debug...done.
   (gdb)

Procedure

1. To find the location of debug symbols, use gdb with which java commands:

   $ gdb which java
   
   Reading symbols from /usr/bin/java...Reading symbols from /usr/lib/debug/usr/lib/jvm/java-21-openjdk-version/bin/java-version.x86_64.debug...done.
   (gdb)

2. Use the following commands to explore the *-debug directory to see all the debug versions of the libraries, which include java, javac, and javah:

   $ cd /usr/lib/debug/lib/jvm/java-21-openjdk-version

   $ tree
   
   OJDK 21 version:
   └── java-21-openjdk-version
   ├── bin
   │   ...
   │ │──  java-java-version.x86_64.debug
   │   ├── javac-java-version.x86_64.debug
   │   ├── javadoc-java-version.x86_64.debug
   │   ...
   └── lib
   ├── jexec-java-version.x86_64.debug
   ├── jli
   │   └── libjli.so-java-version.x86_64.debug
   ├── jspawnhelper-java-version.x86_64.debug
   │   ...

Procedure

1. You can remove all the debug symbols by using the strip -g command.

   The following code shows an example of non-stripped hs_error file:

   Native frames: (J=compiled Java code, j=interpreted, Vv=VM code, C=native code)
   V  [libjvm.so+0xb83d2a]  Unsafe_SetLong+0xda
   j  sun.misc.Unsafe.putLong(Ljava/lang/Object;JJ)V+0
   j  Crash.main([Ljava/lang/String;)V+8
   v  ~StubRoutines::call_stub
   V  [libjvm.so+0x6c0e65]  JavaCalls::call_helper(JavaValue*, methodHandle*, JavaCallArguments*, Thread*)+0xc85
   V  [libjvm.so+0x73cc0d]  jni_invoke_static(JNIEnv_*, JavaValue*, _jobject*, JNICallType, _jmethodID*, JNI_ArgumentPusher*, Thread*) [clone .constprop.1]+0x31d
   V  [libjvm.so+0x73fd16]  jni_CallStaticVoidMethod+0x186
   C  [libjli.so+0x48a2]  JavaMain+0x472
   C  [libpthread.so.0+0x9432]  start_thread+0xe2

   The following code shows an example of stripped hs_error file:

   Stack: [0x00007ff7e1a44000,0x00007ff7e1b44000],  sp=0x00007ff7e1b42850,  free space=1018k
   Native frames: (J=compiled Java code, j=interpreted, Vv=VM code, C=native code)
   V  [libjvm.so+0xa7ecab]
   j  sun.misc.Unsafe.putAddress(JJ)V+0
   j  Crash.crash()V+5
   j  Crash.main([Ljava/lang/String;)V+0
   v  ~StubRoutines::call_stub
   V  [libjvm.so+0x67133a]
   V  [libjvm.so+0x682bca]
   V  [libjvm.so+0x6968b6]
   C  [libjli.so+0x3989]
   C  [libpthread.so.0+0x7dd5]  start_thread+0xc5

2. Enter the following command to check that you have the same version of debug symbols and the fatal error log file:

   $ java -version

   Note

   You can also use the sudo update-alternatives --config 'java' to complete this check.

3. Use the nm command to ensure that libjvm.so has ELF data and text symbols:

   $ nm /usr/lib/debug/usr/lib/jvm/java-21-openjdk-version/lib/server/libjvm.so-version.x86_64.debug

Procedure

1. Check the current Red Hat build of OpenJDK version:

   $ sudo yum list installed "java*"

   A list of installed Red Hat build of OpenJDK packages displays.

2. Update a specific package. For example:

   $ sudo yum update java-21-openjdk

3. Verify that the update worked by checking the current Red Hat build of OpenJDK versions:

   $ java -version

   Note

   You can install multiple major versions of Red Hat build of OpenJDK on your local system. If you need to switch from one major version to another major version, issue the following command in your command-line interface (CLI) and then follow the onscreen prompts:

   $ sudo update-alternatives --config 'java'

Procedure

1. Remove the existing symbolic link of the generic path to your JDK or JRE.

   For example:

   $ unlink ~/jdks/java-21

2. Install the latest version of the JDK or JRE in your installation location.