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[PATCH] Correct pack memory leak causing git gc to try to exceed ulimit

From
Shawn O. Pearce <spearce@spearce.org>
Date
Jul 9, 2008, 07:10 UTC
Message-ID
<20080709071007.GA31974@spearce.org>

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>
---
 sha1_file.c |    1 +
 1 files changed, 1 insertions(+), 0 deletions(-)
diff --git a/sha1_file.c b/sha1_file.c
index d1c4060..10346b6 100644
--- a/sha1_file.c
+++ b/sha1_file.c
@@ -1609,6 +1609,7 @@ static void *unpack_delta_entry(struct packed_git *p,
 	off_t base_offset;
 
 	base_offset = get_delta_base(p, w_curs, &curpos, *type, obj_offset);
+	unuse_pack(w_curs);
 	base = cache_or_unpack_entry(p, base_offset, &base_size, type, 0);
 	if (!base)
 		die("failed to read delta base object"
-- 
1.5.6.74.g8a5e
Next: Nicolas Pitre
Message 1 of 2 in “Correct pack memory leak causing git gc to try to exceed ulimit”
  1. Correct pack memory leak causing git gc to try to exceed ulimitShawn O. Pearce, Jul 9, 2008
  2. Nicolas PitreJul 10, 2008

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