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Allow Exceptions to propagate out of fold tasks CLJ-1058

Before this change, an java.lang.Exception thrown while processing by a
single task is caught and ignored. Infinite recursion comes from falling
out of the "if(tasks.size() == 1)" block into the following code that
splits multiple tasks.

This change adds a call to Util.sneakyThrow(e) in the catch block.

Demonstration of the problem, from Tom Jack:

user> (require '[clojure.core.reducers :as r])
user> (r/fold (fn ([]) ([ret k v] (+ 3 "foo") ret))
              (into {} (map (juxt identity identity) (range 10000))))
StackOverflowError   clojure.lang.Numbers.add (

Signed-off-by: Stuart Halloway <>
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1 parent 6c318f5 commit 5cc167ad735de5d115e0f4b7158332ad4ef5726c @bruceadams bruceadams committed with stuarthalloway Dec 22, 2013
Showing with 1 addition and 1 deletion.
  1. +1 −1 src/jvm/clojure/lang/
@@ -441,7 +441,7 @@ static public Object foldTasks(List<Callable> tasks, final IFn combinef,
catch(Exception e)
- //aargh
+ throw Util.sneakyThrow(e);

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