Unlike platform threads, virtual threads do not return a name unless explicitly set. From the javadoc:

Virtual threads do not have a thread name by default. The getName method returns the empty string if a thread name is not set.

Given that libraries and frameworks (e.g. Spring) create virtual threads but don't explicitly set a name, the logs don't contain any thread name which affects the troubleshooting experience.
The ability to include threadIds in logback log messages would help deal with this problem.

Another solution could perhaps be to synthesize a thread name, something like:

public String getThreadName() {
    if (this.threadName == null) {
        final Thread currentThread = Thread.currentThread();
        if (currentThread.getName() != null) {
            this.threadName = currentThread.getName();
        } else if (currentThread.isVirtual()) { // replace with the reflective call when building with older JDKs
            this.threadName = "virtual-thread-" + currentThread.threadId();
        } else {
            this.threadName = "unnamed-" + currentThread.threadId();
        }
    }

    return this.threadName;
}

@ceki any thoughts on this?

@danishnawab Thank you for the proposal. See commit 5a36133

That's amazing @ceki, thank you!

It seems that the build failed for some (apparently) temporary errors. Could this be retried? It would be very useful to have this now that Spring Boot has support for virtual threads.

This is part of 1.5 now. I think this can be closed?