Correct pack memory leak causing git gc to try to exceed ulimit

When recursing to unpack a delta base we must unuse_pack() so that the pack window for the current object does not remain pinned in memory while the delta base is itself being unpacked and materialized for our use. On a long delta chain of 50 objects we may need to access 6 different windows from a very large (>3G) pack file in order to obtain all of the delta base content. If the process ulimit permits us to map/allocate only 1.5G we must release windows during this recursion to ensure we stay within the ulimit and transition memory from pack cache to standard malloc, or other mmap needs. Inserting an unuse_pack() call prior to the recursion allows us to avoid pinning the current window, making it available for garbage collection if memory runs low. This has been broken since at least before 1.5.1-rc1, and very likely earlier than that. Its fixed now. :) Signed-off-by: Shawn O. Pearce <spearce@spearce.org> Signed-off-by: Junio C Hamano <gitster@pobox.com>

Shawn O. Pearce committed Jul 9, 2008 at 07:10 UTC eac12e2d4d7fb9b388bdc88bf15cd86cbde91dfd

1 file changed +1

sha1_file.c

@@ -1609,6 +1609,7 @@ static void *unpack_delta_entry(struct packed_git *p,

1609 off_t base_offset;

1610

1611 base_offset = get_delta_base(p, w_curs, &curpos, *type, obj_offset);

1612 + unuse_pack(w_curs);

1613 base = cache_or_unpack_entry(p, base_offset, &base_size, type, 0);

1614 if (!base)

1615 die("failed to read delta base object"