Chapter 3. Debug symbols for Red Hat build of OpenJDK 21 Debug symbols help in investigating a crash in Red Hat build of OpenJDK applications. 3.1. Installing the debug symbols This procedure describes how to install the debug symbols for Red Hat build of OpenJDK. Prerequisites Installed the gdb package on your local sytem. You can issue the sudo yum install gdb command on your CLI to install this package on your local system. Procedure To install the debug symbols, enter the following command: 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. To verify that the debug symbols are installed, enter the following command: 3.2. Checking the installation location of debug symbols This procedure explains how to find the location of debug symbols. Note If the debuginfo package is installed, but you cannot get the installation location of the package, then check if the correct package and java versions are installed. After confirming the versions, check the location of debug symbols again. Prerequisites Installed the gdb package on your local sytem. You can issue the sudo yum install gdb command on your CLI to install this package on your local system. Installed the debug symbols package. See Installing the debug symbols . Procedure To find the location of debug symbols, use gdb with which java commands: Use the following commands to explore the *-debug directory to see all the debug versions of the libraries, which include java , javac , and javah : Note The javac and javah tools are provided by the java-21-openjdk-devel package. You can install the package using the command: USD sudo debuginfo-install java-21-openjdk-devel . 3.3. Checking the configuration of debug symbols You can check and set configurations for debug symbols. Enter the following command to get a list of the installed packages: If some debug information packages have not been installed, enter the following command to install the missing packages: Run the following command if you want to hit a specific breakpoint: The above command completes the following tasks: Handles the SIGSEGV error as the JVM uses SEGV for stack overflow check. Sets pending breakpoints to yes . Calls the break statement in JavaCalls::call function. The function to starts the application in HotSpot (libjvm.so). 3.4. Configuring the debug symbols in a fatal error log file When a Java application is down due to a JVM crash, a fatal error log file is generated, for example: hs_error , java_error . These error log files are generated in current working directory of the application. The crash file contains information from the stack. Procedure 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: The following code shows an example of stripped hs_error file: Enter the following command to check that you have the same version of debug symbols and the fatal error log file: Note You can also use the sudo update-alternatives --config 'java' to complete this check. Use the nm command to ensure that libjvm.so has ELF data and text symbols: Additional resources The crash file hs_error is incomplete without the debug symbols installed. For more information, see Java application down due to JVM crash .

Commands:
sudo debuginfo-install java-21-openjdk sudo debuginfo-install java-21-openjdk-headless
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)
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)
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 │
sudo yum list installed | grep 'java-21-openjdk-debuginfo'
sudo yum debuginfo-install glibc-2.28-151.el8.x86_64 libgcc-8.4.1-1.el8.x86_64 libstdc++-8.4.1-1.el8.x86_64 sssd-client-2.4.0-9.el8.x86_64 zlib-1.2.11-17.el8.x86_64
gdb -ex 'handle SIGSEGV noprint nostop pass' -ex 'set breakpoint pending on' -ex 'break JavaCalls::call' -ex 'run' --args java ./HelloWorld
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
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
java -version
nm /usr/lib/debug/usr/lib/jvm/java-21-openjdk- version /lib/server/libjvm.so- version .x86_64.debug