WAS application fails to start after APM agent installation

Products

• DX SaaS

Issue/Introduction

When installing the APM Java Agent in a WebSphere Application Server (WAS) environment using IBM Java 8, the application fails to start or crashes.

Application logs may show generic I/O debug messages followed by a crash.

Environment

• Product: APM Java Agent (Multiple versions)
• Application Server: IBM WebSphere Application Server (WAS)
• Java Version: IBM Java 1.8.0_211 / 8.0.5.35 (SR5 FP35) or older

Cause

Diagnostic dumps reveal a General Protection Fault (GPF) during JIT compilation of specific agent methods.

Failing Method: com/wily/diagnos/cmp/directives/apply/ClassSettingsApplier.validateTransformation(Lcom/wily/diagnos/cmp/transform/ITransformation;)

This issue is caused by a defect in the IBM JIT (Just-In-Time) compiler when processing certain Java agent instrumentation methods. This is specifically seen in IBM Java 8 builds from early 2019.

Resolution

There are two primary methods to resolve this crash:

Option 1: Update IBM Java SDK

Apply the latest IBM Java 8 SDK fix pack to obtain the most recent JIT compiler fixes. It is recommended to move to 8.0 Service Refresh 8 Fix Pack 65 or higher.

Option 2: JIT Exclusion (Workaround)

If a Java update is not immediately possible, you can bypass the crash by excluding the failing method from JIT compilation. Add the following JVM parameter to your WAS configuration:

-Xjit:exclude={com/wily/diagnos/cmp/directives/apply/ClassSettingsApplier.validateTransformation*}

Additional Information

For more details on identifying JIT compilation failures, refer to the following IBM documentation topics:

Identifying JIT compilation failures
Locating the failing method