Hello, We switched the Jetty builds to Java 21 a while ago, and they randomly fail with a hard deadlock during class initialization.
We tried to understand if we were doing something wrong, but the code compiles fine, and at first glance there seems to be nothing wrong with it, but it may well be a popular Java puzzler that I am not aware of :) We did not see these failures with Java 20, and we do not see them with Java 17. I was wondering if something changed in Java 21 to cause this deadlock? I hope this is the right mailing list for this problem. If not, please let me know. I am an OpenJDK author so I can open an issue about this, but I don't have a reproducer, since it seems a race condition happening randomly. Below you can find more details about this deadlock. Thanks! ---- Taking a thread dump we see one thread in this state: java.lang.Thread.State: RUNNABLE at org.eclipse.jetty.http.HttpFields.build(org.eclipse.jetty.http@12.0.2-SNAPSHOT/HttpFields.java:76) - waiting on the Class initialization monitor for org.eclipse.jetty.http.MutableHttpFields at org.eclipse.jetty.http.HttpFields.<clinit>(org.eclipse.jetty.http@12.0.2-SNAPSHOT/HttpFields.java:67) "ForkJoinPool-1-worker-1" #23 [1457161] daemon prio=5 os_prio=0 cpu=320.77ms elapsed=8870.98s allocated=18414K defined_classes=928 tid=0x00007f6ec0c6a6f0 nid=1457161 waiting on condition [0x00007f6e91ffb000] And other threads are in this state (or similar -- the bottom frame is different but still triggering the clinit of HttpFields): java.lang.Thread.State: RUNNABLE at org.eclipse.jetty.http.HttpTester.parseResponse(org.eclipse.jetty.http@12.0.2-SNAPSHOT/HttpTester.java:274) - waiting on the Class initialization monitor for org.eclipse.jetty.http.HttpFields at org.eclipse.jetty.http.HttpTester.parseResponse(org.eclipse.jetty.http@12.0.2-SNAPSHOT/HttpTester.java:261) "ForkJoinPool-1-worker-2" #24 [1457162] daemon prio=5 os_prio=0 cpu=136.15ms elapsed=8870.96s allocated=3303K defined_classes=340 tid=0x00007f6e4c01ddb0 nid=1457162 waiting on condition [0x00007f6e91efc000] Class hierarchy: MutableHttpFields implements HttpFields.Mutable HttpFields.Mutable extends HttpFields Full thread dump: https://gist.github.com/olamy/7e883adcf51b2410337abfa775a79a0b Code: https://github.com/eclipse/jetty.project/blob/jetty-12.0.1/jetty-core/jetty-http/src/main/java/org/eclipse/jetty/http/HttpFields.java -- Simone Bordet --- Finally, no matter how good the architecture and design are, to deliver bug-free software with optimal performance and reliability, the implementation technique must be flawless. Victoria Livschitz
