Good catch! It appears I just introduced the bug here, by eliminating recursion: https://github.com/mbostock/queue/commit/7bd5059bb2c0a94c0ca21d87b346f59bf7b31d

Good catch! It appears I just introduced the bug here, by eliminating recursion: https://github.com/mbostock/queue/commit/7bd5059bb2c0a94c0ca21d87b346f59bf7b31d02 https://github.com/mbostock/queue/commit/7bd5059bb2c0a94c0ca... Popping multiple synchronous tasks after an asynchronous one is fairly rare, but I’ll make sure the tests verify this code path.