I believe that this is actually a result of Perl 6 delegating responsibility of
memory management for arguments passed to callbacks from native code to the
native code.
I wonder if the issue is that you're sending a constant which is being
reallocated and recreated and never cleared out from the native code.
Keep in mind, however, I've been sick lately and I am on heavy antihistamines,
so I could just have medicine head.
Here's the document I'm drawing this guess from:
https://docs.perl6.org/language/nativecall#Function_arguments
> On Jan 21, 2018, at 19:24, David E. wrote:
>
> I'm not certain where to report this (ie: rakudo vs MoarVM), so I'm starting
> here.
>
> After some experimentation, I finally traced down a segfault I've been
> getting to a memory leak in the NativeCall interface. I'm using it to
> facilitate testing of a 32-bit embedded (meaning no dynamic allocation) C
> library in an easier/more-comprehensive way than I could otherwise -- though
> this memory leak is preventing me from running the long-duration tests that I
> need to.
>
> I'm currently running 2017.12.1 (commit
> c84ed2942d224e4cd524fa389e0603e4e4642f77) under a 32-bit Docker Ubuntu image
> (I started with 2017.10). I can easily observe the memory leak using "docker
> stats". At it's worst, with my full application, I'm seeing approximately
> 0.01 GiB of memory per second getting lost.
>
> Below is sample code that is able to reproduce the leak. I believe that it
> has something to do with the callback, maybe with the C-string conversion.
>
> Please advise,
> thanks,
> -David
>
>
> test_memleak.pl6:
> use v6;
> use NativeCall;
>
> constant LIB_DTEST = 'libtestlib.so';
>
> sub dtest_log_init(&dt_csv_log (Str)) is native(LIB_DTEST) {*};
> sub test_cb() is native(LIB_DTEST) {*};
>
> sub dt_csv_log(Str $data)
> {
> prompt "dt_csv_log($data)";
> }
>
> sub MAIN()
> {
> dtest_log_init(&dt_csv_log);
>
> while 1 {
> # prompt "Call test_cb()";
> test_cb();
> }
> }
>
> test_memleak.c:
> #include
> void (*dtlf)(char* s);
> void dtest_log_init(void (*fp)(char* s))
> {
> printf("Assigning dtlf to fp=0x%x\n", (int)fp);
>dtlf = fp;
> }
> void test_cb(void)
> {
> dtlf("test_cb");
> }
>
> The following is a snippet from my Dockerfile that installed perl6:
> && git clone https://github.com/rakudo/rakudo/
> /root/rakudo \
> && echo 'export
> PATH="$HOME/rakudo/install/bin:$HOME/rakudo/install/share/perl6/site/bin:$PATH"'
> >> ~/.bashrc \
> && cd ~/rakudo && git checkout master && git pull \
> && git checkout $(git describe --abbrev=0 --tags) \
> && perl Configure.pl --gen-moar --gen-nqp --backends=moar \
> && make && make install \
>
