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Date: Tue, 30 Dec 2014 10:40:43 +0300
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Subject: Re: programs using kgio crash under memory pressure during init
From: Hleb Valoshka <375gnu@gmail.com>
To: Petr Novodvorskiy <nidd@skytap.com>
Cc: kgio-public@bogomips.org, Lara Martin <lmartin@skytap.com>,  Nick Astete
 <nastete@skytap.com>
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On 12/30/14, Petr Novodvorskiy <nidd@skytap.com> wrote:
> After looking in the code, I think I was able to identify the problem. In
> init_kgio_tryopen(), when rb_funcall is called to get list of errno
> constants, it doesn't protect returned list from garbage collecting. I made
> modification (below) that seemed to fix the problem (I wasn't able to
> reproduce it anymore).

> +        tmp = rb_protect(get_err_constants, (VALUE)NULL, &exception);

I don't know why does it help, but rb_protect is wrong function for
your purpose:
VALUE rb_protect(VALUE (*func) (VALUE), VALUE arg, int *state)

    Calls the function func with arg as the argument. If no exception
occured during func, it returns the result of func and *state is zero.
Otherwise, it returns Qnil and sets *state to nonzero. If state is
NULL, it is not set in both cases. You have to clear the error info
with rb_set_errinfo(Qnil) when ignoring the caught exception.