RFR: 8348239: SA does not know about DeoptimizeObjectsALotThread

[Dean Long]

On Thu, 23 Jan 2025 20:15:35 GMT, Chris Plummer <cjplummer at openjdk.org> wrote:

> If you run hotspot with -XX:+DeoptimizeObjectsALot, it will create one or more DeoptimizeObjectsALotThread threads. This is one of many JavaThread subclasses that SA needs to know about, but in this case it does not. When SA tries to create a mirror of one of these threads, it fails with:
> 
> 
>  stderr: [java.lang.RuntimeException: Unable to deduce type of thread from address 0x0000ffff34144e30 (expected type JavaThread, CompilerThread, MonitorDeflationThread, AttachListenerThread, StringDedupThread, NotificationThread, ServiceThread or JvmtiAgentThread)
> at jdk.hotspot.agent/sun.jvm.hotspot.runtime.Threads.createJavaThreadWrapper(Threads.java:196)
> at jdk.hotspot.agent/sun.jvm.hotspot.runtime.Threads.getJavaThreadAt(Threads.java:178)
> 
> 
> The following can be used to reproduce this failure. Most SA tests will fail:
> 
>  make test TEST=serviceability/sa TEST_VM_OPTS=-XX:+DeoptimizeObjectsALot 
> 
> I had to move the native DeoptimizeObjectsALotThread declaration to compileBroker.hpp to make it visible to vmStructs.cpp.
> 
> I tested with the above "make test" command and ran all svc tier1, tier2, tier3, and tier5 tests.

src/jdk.hotspot.agent/share/classes/sun/jvm/hotspot/runtime/Thread.java line 92:

> 90:   public boolean   isMonitorDeflationThread()    { return false; }
> 91:   public boolean   isAttachListenerThread()      { return false; }
> 92:   public boolean   isDeoptimizeObjectsALotThread() { return false; }

Is this method used anywhere?

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PR Review Comment: https://git.openjdk.org/jdk/pull/23279#discussion_r1927740178