Re: cdata finalizer called twice
- From: Peter Colberg <peter@xxxxxxxxxxx>
- To: luajit@xxxxxxxxxxxxx
- Date: Thu, 13 Nov 2014 22:58:49 -0500
On Thu, Nov 13, 2014 at 09:13:11PM +0100, Mike Pall wrote:
> It shouldn't. Provide a self-contained example.
Thank you so far for taking the time to reply to every message.
I spent many hours reducing the application to produce an example, but
the more parts are disabled, the less likely it becomes that a cdata
object is finalized twice; until the probability of failure becomes so
small that I cannot reproduce the error within a reasonable runtime.
After some experimentation I found that duplicate finalization occurs
only when ffi.gc() is both compiled and invoked in a tail call.
This method of constructing objects works fine:
ffi.cdef[[typedef struct _cl_event *cl_event;]]
local event_ptr = ffi.new("cl_event[1]")
local function enqueue_marker(queue)
assert(C.CL_SUCCESS == C.clEnqueueMarker(queue, event_ptr))
local event = ffi.gc(event_ptr[0], release_event) -- no tail call
return event
end
This method of constructing objects causes duplicate finalization:
local function enqueue_marker(queue)
assert(C.CL_SUCCESS == C.clEnqueueMarker(queue, event_ptr))
return ffi.gc(event_ptr[0], release_event) -- tail call
end
Peter
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