Chapter 3. Debug symbols for Red Hat build of OpenJDK 17

Procedure

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

   $ sudo debuginfo-install java-17-openjdk
   
   $ sudo debuginfo-install java-17-openjdk-headless

   These commands install java-17-openjdk-debuginfo, java-17-openjdk-headless-debuginfo, and additional packages that provide debug symbols for Red Hat build of OpenJDK 17 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-17-openjdk-17.0.2.0.8-4.el8_5/bin/java-17.0.2.0.8-4.el8_5.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-17-openjdk-17.0.2.0.8-4.el8_5/bin/java-17.0.2.0.8-4.el8_5.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-17-openjdk-17.0.2.0.8-4.el8_5

   $ tree
   
   OJDK 17 version:
   └── java-17-openjdk-17.0.2.0.8-4.el8_5
   ├── bin
   │   ...
   │ │──  java-java-17.0.2.0.8-4.el8_5.x86_64.debug
   │   ├── javac-java-17.0.2.0.8-4.el8_5.x86_64.debug
   │   ├── javadoc-java-17.0.2.0.8-4.el8_5.x86_64.debug
   │   ...
   └── lib
   ├── jexec-java-17.0.2.0.8-4.el8_5.x86_64.debug
   ├── jli
   │   └── libjli.so-java-17.0.2.0.8-4.el8_5.x86_64.debug
   ├── jspawnhelper-java-17.0.2.0.8-4.el8_5.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-17-openjdk-17.0.2.0.8-4.el8_5/lib/server/libjvm.so-17.0.2.0.8-4.el8_5.x86_64.debug