Issue with multi-agent loading

[ananthvanchip]

Hi,

I built a custom agent (and extension of open-telemetry agent) and I also have glowroot agent for my Java application.. when i add both the agent's to my application, during loading, i get this exception.. it only shows up when i enabled debug logs. There is no error in application startup. I dont see any functional issues (broadly) in my application or agent). But I m unable to understand why this error occurs.

2025-07-17 12:06:55:255 +0530] [main] DEBUG com.ck.javaagent.tooling.AgentInstaller$TransformLoggingListener - Failed to handle org.glowroot.agent.plugin.servlet.CatalinaAppStartupAspect for transformation on class loader null
net.bytebuddy.pool.TypePool$Resolution$NoSuchTypeException: Cannot resolve type description for org.glowroot.agent.plugin.servlet.CatalinaAppStartupAspect
    at net.bytebuddy.pool.TypePool$Resolution$Illegal.resolve(TypePool.java:192)
    at com.ck.javaagent.tooling.muzzle.AgentCachingPoolStrategy$AgentTypePool$CachingTypeDescription.delegate(AgentCachingPoolStrategy.java:422)
    at net.bytebuddy.description.type.TypeDescription$AbstractBase$OfSimpleType$WithDelegation.getModifiers(TypeDescription.java:8601)
    at net.bytebuddy.matcher.ModifierMatcher.doMatch(ModifierMatcher.java:60)
    at net.bytebuddy.matcher.ModifierMatcher.doMatch(ModifierMatcher.java:27)
    at net.bytebuddy.matcher.ElementMatcher$Junction$ForNonNullValues.matches(ElementMatcher.java:252)
    at net.bytebuddy.matcher.NegatingMatcher.matches(NegatingMatcher.java:47)
    at net.bytebuddy.matcher.ElementMatcher$Junction$Conjunction.matches(ElementMatcher.java:148)
    at com.ck.javaagent.tooling.util.IgnoreFailedTypeMatcher.matches(IgnoreFailedTypeMatcher.java:27)
    at com.ck.javaagent.tooling.util.IgnoreFailedTypeMatcher.matches(IgnoreFailedTypeMatcher.java:18)
    at com.ck.javaagent.tooling.util.NamedMatcher.matches(NamedMatcher.java:26)
    at net.bytebuddy.agent.builder.AgentBuilder$RawMatcher$ForElementMatchers.matches(AgentBuilder.java:1965)
    at net.bytebuddy.agent.builder.AgentBuilder$RawMatcher$Conjunction.matches(AgentBuilder.java:1800)
    at net.bytebuddy.agent.builder.AgentBuilder$Default$Transformation$SimpleMatcher.matches(AgentBuilder.java:12189)
    at net.bytebuddy.agent.builder.AgentBuilder$RedefinitionStrategy$Collector.doConsider(AgentBuilder.java:8388)
    at net.bytebuddy.agent.builder.AgentBuilder$RedefinitionStrategy$Collector.consider(AgentBuilder.java:8333)
    at net.bytebuddy.agent.builder.AgentBuilder$RedefinitionStrategy.apply(AgentBuilder.java:6119)
    at net.bytebuddy.agent.builder.AgentBuilder$Default.doInstall(AgentBuilder.java:11736)
    at net.bytebuddy.agent.builder.AgentBuilder$Default.installOn(AgentBuilder.java:11636)
    at com.ck.javaagent.tooling.AgentInstaller.installBytebuddyAgent(AgentInstaller.java:203)
    at com.ck.javaagent.tooling.AgentInstaller.installBytebuddyAgent(AgentInstaller.java:110)
    at com.ck.javaagent.tooling.AgentStarterImpl.start(AgentStarterImpl.java:101)
    at com.ck.javaagent.bootstrap.AgentInitializer$2.run(AgentInitializer.java:69)
    at com.ck.javaagent.bootstrap.AgentInitializer$2.run(AgentInitializer.java:63)
    at com.ck.javaagent.bootstrap.AgentInitializer.execute(AgentInitializer.java:85)
    at com.ck.javaagent.bootstrap.AgentInitializer.initialize(AgentInitializer.java:62)
    at com.ck.javaagent.OpenTelemetryAgent.startAgent(OpenTelemetryAgent.java:59)
    at com.ck.javaagent.OpenTelemetryAgent.premain(OpenTelemetryAgent.java:46)
    at java.base/jdk.internal.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
    at java.base/jdk.internal.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:77)
    at java.base/jdk.internal.reflect.DelegatingMet

There are many classes such as the CatalinaAppStartupAspect which have the same exception while startup.. Can someone tell why this is happening. Is it an issue to bother about and how to fix it?

[raphw]

If you do not try to instrument the related types, it does not matter. You can avoid the error, by explicitly ignoring types of the specified package. For example startsWith("org.glowroot.agent."). This is likely happening because another agent is present but those dynamically added agents do not expose their class files to the default lookup mechanism.