Hi Nick,

I believe that a closure created with buildClosureX is not automatically garbage collected because Poly/ML can't know how long a C function is going to hold on to the callback for. Therefore, I suspect what's happening is that Poly/ML can't garbage collect the list accum because that is referenced by the callback function which is referenced by the closure. This is desirable behaviour: accum is needed as long as there is a chance that the callback can be called. If you clear out the contents of accum explicitly then those contents can be garbage collected but accum itself still won't be. That's my guess - I haven't tested this hypothesis.

Phil

On 14/03/19 14:01, Kostirya wrote:

Hello.

I found memory leak when FFI callback and ref value. I checked Poly/ML 5.8 and 5.7. Simple code for reproduce the memory leak is attached.

To prevent the memory leak I clean ref value (see comment in example). But It must do the garbage collector, is it? At least MLton have not this problem.

Result of run of example code:

Without clean ref value (The memory leak is) USER PID %CPU %MEM VSZ RSS TT STAT STARTED TIME COMMAND nick 19855 91,8 9,7 305016 289452 6 S+ 16:53 0:17,94 poly --script cb-po

With clean ref value USER PID %CPU %MEM VSZ RSS TT STAT STARTED TIME COMMAND nick 19862 65,3 0,6 32632 17476 6 S+ 16:54 0:10,77 poly --script cb-poly

Best, Nick.

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