Re: possible memory leak in 2.1 (not in 2.0.3)
- From: Valerio Schiavoni <valerio.schiavoni@xxxxxxxxx>
- To: luajit@xxxxxxxxxxxxx
- Date: Sat, 26 Jul 2014 12:47:14 +0200
On Fri, Jul 25, 2014 at 8:30 PM, Mike Pall <mike-1407@xxxxxxxxxx> wrote:
> Valerio Schiavoni wrote:
>> On my machine (Mac OSX 10.9), LuaJIT 2.1 (freshly cloned) crashes more
>> or less around the the time the program prints '651' (thought slight
>> variations might occur).
>> LuaJIT 2.0.3 works just fine.
>
> I get the out-of-memory condition in various versions and 32/64 bit
> variants, just at different places. It may happen for plain Lua, too.
I could not reproduce it with plain Lua 5.2.3, at least not on mac osx
10.9 or ubuntu 14 lts.
> The Lua/LuaJIT garbage collector is only driven forward on regular
> allocations, but not when growing a table.
>
> There are only two allocations here: the 'local i_dist={}' and the
> implicit string creation in 'print(i)'. LuaJIT doesn't even need an
> allocation for the latter, i.e. it only performs half the GC steps.
>
> But there are lots of table growths inbetween. So, even if the GC
> starts a cycle at some point in time, it may not catch up and
> perform enough incremental steps to complete the cycle before
> memory runs out.
>
> There have been various reports on the Lua mailing list about this
> issue, esp. with big userdata allocations. IMHO it's quite
> difficult to modify the current GC to handle that better. Tuning
> GC heuristics to perform well under all kinds of mutator loads is
> really, really hard.
Would you suggest, as possible workaround, a pre-allocation of the
i_dist table with nil values, thus avoiding the table growths during
the iteration ?
Would that somehow help the luajit vm ?
Thanks,
Valerio
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