Re: fatal: Out of memory, getdelim failed under NFS mounts

From

Yaroslav Halchenko <yoh@onerussian.com>

Date

Aug 10, 2017, 19:44 UTC

Message-ID

<20170810194438.n6cmljlorind2enu@hopa.kiewit.dartmouth.edu>

In-Reply-To

<xmqqzib72qvs.fsf@gitster.mtv.corp.google.com>

Thank you Junio

On Thu, 10 Aug 2017, Junio C Hamano wrote:

> There is only one getdelim() call, which was introduced in v2.5.0
> timeframe, and it is used like this:

> 	r = getdelim(&sb->buf, &sb->alloc, term, fp);

> 	if (r > 0) {
> 		sb->len = r;
> 		return 0;
> 	}
> 	assert(r == -1);

> 	/*
> 	 * Normally we would have called xrealloc, which will try to free
> 	 * memory and recover. But we have no way to tell getdelim() to do so.
> 	 * Worse, we cannot try to recover ENOMEM ourselves, because we have
> 	 * no idea how many bytes were read by getdelim.
> 	 *
> 	 * Dying here is reasonable. It mirrors what xrealloc would do on
> 	 * catastrophic memory failure. We skip the opportunity to free pack
> 	 * memory and retry, but that's unlikely to help for a malloc small
> 	 * enough to hold a single line of input, anyway.
> 	 */
> 	if (errno == ENOMEM)
> 		die("Out of memory, getdelim failed");

> So the function is returning -1 and leaving ENOMEM in errno on
> Yaroslav's system.  

> I wonder if we are truly hitting out of memory, though.  The same
> symptom could bee seen if getdelim() does not touch errno when it
> returns -1, but some other system call earlier set it to ENOMEM,
> for example.

> If the same version of Git is recompiled there without HAVE_GETDELIM
> defined, would it still die with out of memory (presumably inside
> the call to strbuf_grow() in the strbuf_getwholeline() function)?

-- 
Yaroslav O. Halchenko
Center for Open Neuroscience     http://centerforopenneuroscience.org
Dartmouth College, 419 Moore Hall, Hinman Box 6207, Hanover, NH 03755
Phone: +1 (603) 646-9834                       Fax: +1 (603) 646-1419
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