[GR-42095] Track object instantiation presenting stacktraces that are not possible

[galderz]

Trace object instantiation can at times show stacktraces that will never be invoked by the application. You can find an example in Quarkus's Native Reference guide.

In there, a class that is build time initialized, initializes a cryptographic key pair in a static block:

public class EncryptDecryptResource {

    static final KeyPairGenerator KEY_PAIR_GEN;

    static {
        try {
            KEY_PAIR_GEN = KeyPairGenerator.getInstance("RSA");
            KEY_PAIR_GEN.initialize(1024);
        } catch (NoSuchAlgorithmException | NoSuchPaddingException e) {
            throw new RuntimeException(e);
        }
    }

This causes an error because it would lead to a SecureRandom ending up in the build time heap:

Error: Unsupported features in 2 methods
Detailed message:
Error: Detected an instance of Random/SplittableRandom class in the image heap. Instances created during image generation have cached seed values and don't behave as expected.  To see how this object got instantiated use --trace-object-instantiation=java.security.SecureRandom. The object was probably created by a class initializer and is reachable from a static field. You can request class initialization at image runtime by using the option --initialize-at-run-time=<class-name>. Or you can write your own initialization methods and call them explicitly from your main entry point.
Trace: Object was reached by
	reading field java.security.KeyPairGenerator$Delegate.initRandom of
		constant java.security.KeyPairGenerator$Delegate@58b0fe1b reached by
	reading field org.acme.EncryptDecryptResource.KEY_PAIR_GEN
Error: Detected an instance of Random/SplittableRandom class in the image heap. Instances created during image generation have cached seed values and don't behave as expected.  To see how this object got instantiated use --trace-object-instantiation=java.security.SecureRandom. The object was probably created by a class initializer and is reachable from a static field. You can request class initialization at image runtime by using the option --initialize-at-run-time=<class-name>. Or you can write your own initialization methods and call them explicitly from your main entry point.
Trace: Object was reached by
	reading field sun.security.rsa.RSAKeyPairGenerator.random of
		constant sun.security.rsa.RSAKeyPairGenerator$Legacy@3248a092 reached by
	reading field java.security.KeyPairGenerator$Delegate.spi of
		constant java.security.KeyPairGenerator$Delegate@58b0fe1b reached by
	reading field org.acme.EncryptDecryptResource.KEY_PAIR_GEN

If you then pass in --trace-object-instantiation=java.security.SecureRandom to track object instantiation, it shows the following stacktrace, which is not something the application will call:

Error: Detected an instance of Random/SplittableRandom class in the image heap. Instances created during image generation have cached seed values and don't behave as expected.  Object has been initialized by the com.sun.jndi.dns.DnsClient class initializer with a trace:
 	at java.security.SecureRandom.<init>(SecureRandom.java:218)
	at sun.security.jca.JCAUtil$CachedSecureRandomHolder.<clinit>(JCAUtil.java:59)
	at sun.security.jca.JCAUtil.getSecureRandom(JCAUtil.java:69)
	at com.sun.jndi.dns.DnsClient.<clinit>(DnsClient.java:82)

Sure, the DnsClient caches a SecureRandom statically, but the application doesn't call this. This kind of error reporting can be very confusing for the end user.

[oubidar-Abderrahim]

Hi, Thank you for reporting this. this is tracked internally GR 42095

[wirthi]

I understand why you state that the trace is confusing. It is not representing the call stack visible to the user, it is representing in the internal root cause chain how and why a class was initialized. Your message in the docs is reasonable - it is a tool to figure out the root cause, not the "call stack" of actual invocations.

We cannot easily change that without a lot of effort.