throwIfFailed throws an exception that wraps one thrown by the child as a "caused by" and lists their stack traces. Java users have had this for many years, but

throwIfFailed throws an exception that wraps one thrown by the child as a "caused by" and lists their stack traces. Java users have had this for many years, but threads were simply costly, so they were shared among tasks. The new thing structured concurrency brings -- in addition to making some best practices easier to follow -- is that the runtime now records parent-child relationships among threads (that now make sense when threads are no longer shared). You can see these relationships and the tree hierarchy for the entire application with a new JSON thread-dump.