03 August 2024
Alex Miller
Clojure 1.11.4 is now available with the following fixes:
CLJ-2145 Fix clearing of closed overs in ^:once fns
In some cases (see the ticket for details), functions that closed-over bindings in the outer scope were not clearing the use of those bindings in the inner function scope, which could potentially cause head-holding. These closed-overs are now clearable for garbage collection.
CLJ-2317 recur to head of :once fn cancels once
The :once function metadata is a hint to the compiler that a function will only be run once, and thus closed-over fields may be cleared. It is nonsensical to recur to the head of a :once fn (as that implies running it more than once), but this situation can arise through the use of macros that apply wrap arbitrary bodies in :once fns. In this case closed-over fields would sometimes be cleared prior to the recur. Now, use of recur to the head of a :once fn will ignore the :once flag and closed-over fields will not be cleared in the fn. Clearing of other local fields (not closed-over) is unchanged.
