ADDITIONAL SYSTEM INFORMATION :
Property settings:
    awt.toolkit = sun.awt.X11.XToolkit
    file.encoding = UTF-8
    file.encoding.pkg = sun.io
    file.separator = /
    java.awt.graphicsenv = sun.awt.X11GraphicsEnvironment
    java.awt.printerjob = sun.print.PSPrinterJob
    java.class.path = .
    java.class.version = 52.0
    java.endorsed.dirs = /usr/lib/jvm/java-8-openjdk-new/jdk8u472-b08/jre/lib/endorsed
    java.ext.dirs = /usr/lib/jvm/java-8-openjdk-new/jdk8u472-b08/jre/lib/ext
        /usr/java/packages/lib/ext
    java.home = /usr/lib/jvm/java-8-openjdk-new/jdk8u472-b08/jre
    java.io.tmpdir = /tmp
    java.library.path = /usr/java/packages/lib/amd64
        /usr/lib64
        /lib64
        /lib
        /usr/lib
    java.runtime.name = OpenJDK Runtime Environment
    java.runtime.version = 1.8.0_472-b08
    java.specification.maintenance.version = 6
    java.specification.name = Java Platform API Specification
    java.specification.vendor = Oracle Corporation
    java.specification.version = 1.8
    java.vendor = Temurin
    java.vendor.url = https://adoptium.net/
    java.vendor.url.bug = https://github.com/adoptium/adoptium-support/issues
    java.version = 1.8.0_472
    java.vm.info = mixed mode
    java.vm.name = OpenJDK 64-Bit Server VM
    java.vm.specification.name = Java Virtual Machine Specification
    java.vm.specification.vendor = Oracle Corporation
    java.vm.specification.version = 1.8
    java.vm.vendor = Temurin
    java.vm.version = 25.472-b08
    line.separator = \n
    os.arch = amd64
    os.name = Linux
    os.version = 4.15.0-196-generic
    path.separator = :
    sun.arch.data.model = 64
    sun.boot.class.path = /usr/lib/jvm/java-8-openjdk-new/jdk8u472-b08/jre/lib/resources.jar
        /usr/lib/jvm/java-8-openjdk-new/jdk8u472-b08/jre/lib/rt.jar
        /usr/lib/jvm/java-8-openjdk-new/jdk8u472-b08/jre/lib/sunrsasign.jar
        /usr/lib/jvm/java-8-openjdk-new/jdk8u472-b08/jre/lib/jsse.jar
        /usr/lib/jvm/java-8-openjdk-new/jdk8u472-b08/jre/lib/jce.jar
        /usr/lib/jvm/java-8-openjdk-new/jdk8u472-b08/jre/lib/charsets.jar
        /usr/lib/jvm/java-8-openjdk-new/jdk8u472-b08/jre/lib/jfr.jar
        /usr/lib/jvm/java-8-openjdk-new/jdk8u472-b08/jre/classes
    sun.boot.library.path = /usr/lib/jvm/java-8-openjdk-new/jdk8u472-b08/jre/lib/amd64
    sun.cpu.endian = little
    sun.cpu.isalist =
    sun.io.unicode.encoding = UnicodeLittle
    sun.java.launcher = SUN_STANDARD
    sun.jnu.encoding = UTF-8
    sun.management.compiler = HotSpot 64-Bit Tiered Compilers
    sun.os.patch.level = unknown
    user.dir = [EDITED]
    user.home = /root
    user.language = en
    user.name = root
    user.timezone =

openjdk version "1.8.0_472"
OpenJDK Runtime Environment (Temurin)(build 1.8.0_472-b08)
OpenJDK 64-Bit Server VM (Temurin)(build 25.472-b08, mixed mode)

A DESCRIPTION OF THE PROBLEM :
CPU: Intel Xeon (inferred from environment; exact model not in log, but architecture is linux-amd64)
OS: Linux (amd64)
JRE Version: OpenJDK Runtime Environment (8.0_452-b09) (build 1.8.0_452-8u452-ga～us1-0ubuntu1～20.04-b09)
Java VM: OpenJDK 64-Bit Server VM (25.452-b09, mixed mode, linux-amd64, compressed oops)
Heap Configuration: G1 GC, 256 MB heap (garbage-first heap total 262144K)
Issue Description:
The JVM crashed with a SIGSEGV (segmentation fault) during execution. The crash occurred in the VMThread, which is responsible for internal JVM operations such as garbage collection. The problematic frame points to native code within libjvm.so, specifically during a G1 garbage collection pause (G1IncCollectionPause). This strongly suggests a bug in the JVM’s garbage collector implementation—potentially related to Remembered Set (RSet) processing or concurrent marking structures.
Error Details:
Signal: SIGSEGV (0xb)
Signal Code: SEGV_ACCERR (0x2) — invalid memory access (permission error)
Faulting Address: 0x00007f62f47f49e8
Problematic Frame:
V [libjvm.so+0x5a5835]
Note: While the exact symbol name (e.g., RSHashTableIter::has_next) is not present in this log due to lack of debug symbols, the crash occurs at offset 0x5a5835 in libjvm.so during a G1 incremental collection pause, consistent with RSet or card table iteration logic.
Thread Context:
Crashing Thread: VMThread (native thread ID 19711, Java thread pointer 0x00007f62f43d0000)
VM Operation: G1IncCollectionPause
VM State: at safepoint (normal execution)
Held Locks:
Threads_lock (owned by VMThread)
Heap_lock (owned by Java thread pool-1-thread-1, which triggered the GC)
This confirms the crash happened inside JVM internal GC code, not in application-level Java code.
Supporting Evidence from Log:
GC type: G1 Garbage Collector
Heap usage at crash: ～102 MB used out of 256 MB
Metaspace usage: ～8 MB
Core dump written to: [EDITED]/core or core.19642

STEPS TO FOLLOW TO REPRODUCE THE PROBLEM :
Steps to Reproduce:

1. Clone the reproduction repository:
   $ [EDITED]
   $ cd BugReport

2. Extract the reproduction case (if compressed):
   $ unzip GCtestcase-2.zip

3. Compile and Run the reproduction script:

   Before running the script, please edit execution.properties and update the jvm and javac paths to point to your local installation.

   $ bash ./scripts/replay.sh -s sequence.json -t com/gcscheduling/generated/ConcurrentTest_20260110_014123_560.java -p vmoption.vmopts


---------- BEGIN SOURCE ----------
[EDITED]

---------- END SOURCE ----------

CUSTOMER SUBMITTED WORKAROUND :
Reproducing this issue requires a custom Java agent (provided as a .jar file) that instruments class loading and garbage collection behavior in a specific way. This agent is essential to trigger the exact sequence of events leading to the crash.
To ensure the reproduction environment is complete and self-contained, we have packaged:
The Java agent JAR,
The generated test class,
The JVM options (vmopts),
And the execution script,
into a single archive (GCtestcase-1.zip) hosted in a public GitHub repository.


FREQUENCY :
OFTEN