From ce498e094e8db32fff358ecf7e4ad4951e6bebce Mon Sep 17 00:00:00 2001 From: Johannes Schindelin Date: Tue, 16 Oct 2018 14:02:49 -0700 Subject: [PATCH 1/3] pack-objects: fix typo 'detla' -> 'delta' Signed-off-by: Johannes Schindelin Signed-off-by: Junio C Hamano --- pack-objects.h | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/pack-objects.h b/pack-objects.h index 62806ccc39..c34036166a 100644 --- a/pack-objects.h +++ b/pack-objects.h @@ -356,7 +356,7 @@ static inline unsigned long oe_delta_size(struct packing_data *pack, return e->delta_size_; /* - * pack->detla_size[] can't be NULL because oe_set_delta_size() + * pack->delta_size[] can't be NULL because oe_set_delta_size() * must have been called when a new delta is saved with * oe_set_delta(). * If oe_delta() returns NULL (i.e. default state, which means From 9308f45a9f1e3e107ba53a91d0f0c59342cb32bd Mon Sep 17 00:00:00 2001 From: Johannes Schindelin Date: Tue, 16 Oct 2018 14:02:50 -0700 Subject: [PATCH 2/3] pack-objects (mingw): demonstrate a segmentation fault with large deltas There is a problem in the way 9ac3f0e5b3e4 (pack-objects: fix performance issues on packing large deltas, 2018-07-22) initializes that mutex in the `packing_data` struct. The problem manifests in a segmentation fault on Windows, when a mutex (AKA critical section) is accessed without being initialized. (With pthreads, you apparently do not really have to initialize them?) This was reported in https://github.com/git-for-windows/git/issues/1839. Signed-off-by: Johannes Schindelin Signed-off-by: Junio C Hamano --- t/t5321-pack-large-objects.sh | 32 ++++++++++++++++++++++++++++++++ 1 file changed, 32 insertions(+) create mode 100755 t/t5321-pack-large-objects.sh diff --git a/t/t5321-pack-large-objects.sh b/t/t5321-pack-large-objects.sh new file mode 100755 index 0000000000..c36c66fbb4 --- /dev/null +++ b/t/t5321-pack-large-objects.sh @@ -0,0 +1,32 @@ +#!/bin/sh +# +# Copyright (c) 2018 Johannes Schindelin +# + +test_description='git pack-object with "large" deltas + +' +. ./test-lib.sh +. "$TEST_DIRECTORY"/lib-pack.sh + +# Two similar-ish objects that we have computed deltas between. +A=01d7713666f4de822776c7622c10f1b07de280dc +B=e68fe8129b546b101aee9510c5328e7f21ca1d18 + +test_expect_success 'setup' ' + clear_packs && + { + pack_header 2 && + pack_obj $A $B && + pack_obj $B + } >ab.pack && + pack_trailer ab.pack && + git index-pack --stdin Date: Tue, 16 Oct 2018 14:02:52 -0700 Subject: [PATCH 3/3] pack-objects (mingw): initialize `packing_data` mutex in the correct spot In 9ac3f0e5b3e4 (pack-objects: fix performance issues on packing large deltas, 2018-07-22), a mutex was introduced that is used to guard the call to set the delta size. This commit even added code to initialize it, but at an incorrect spot: in `init_threaded_search()`, while the call to `oe_set_delta_size()` (and hence to `packing_data_lock()`) can happen in the call chain `check_object()` <- `get_object_details()` <- `prepare_pack()` <- `cmd_pack_objects()`, which is long before the `prepare_pack()` function calls `ll_find_deltas()` (which initializes the threaded search). Another tell-tale that the mutex was initialized in an incorrect spot is that the function to initialize it lives in builtin/, while the code that uses the mutex is defined in a libgit.a header file. Let's use a more appropriate function: `prepare_packing_data()`, which not only lives in libgit.a, but *has* to be called before the `packing_data` struct is used that contains that mutex. This fixes https://github.com/git-for-windows/git/issues/1839. Signed-off-by: Johannes Schindelin Signed-off-by: Junio C Hamano --- builtin/pack-objects.c | 1 - pack-objects.c | 3 +++ t/t5321-pack-large-objects.sh | 2 +- 3 files changed, 4 insertions(+), 2 deletions(-) diff --git a/builtin/pack-objects.c b/builtin/pack-objects.c index d1144a8f7e..29d48f3867 100644 --- a/builtin/pack-objects.c +++ b/builtin/pack-objects.c @@ -2299,7 +2299,6 @@ static void init_threaded_search(void) pthread_mutex_init(&cache_mutex, NULL); pthread_mutex_init(&progress_mutex, NULL); pthread_cond_init(&progress_cond, NULL); - pthread_mutex_init(&to_pack.lock, NULL); old_try_to_free_routine = set_try_to_free_routine(try_to_free_from_threads); } diff --git a/pack-objects.c b/pack-objects.c index 6ef87e5683..f73f609884 100644 --- a/pack-objects.c +++ b/pack-objects.c @@ -148,6 +148,9 @@ void prepare_packing_data(struct packing_data *pdata) 1U << OE_SIZE_BITS); pdata->oe_delta_size_limit = git_env_ulong("GIT_TEST_OE_DELTA_SIZE", 1UL << OE_DELTA_SIZE_BITS); +#ifndef NO_PTHREADS + pthread_mutex_init(&pdata->lock, NULL); +#endif } struct object_entry *packlist_alloc(struct packing_data *pdata, diff --git a/t/t5321-pack-large-objects.sh b/t/t5321-pack-large-objects.sh index c36c66fbb4..a75eab87d3 100755 --- a/t/t5321-pack-large-objects.sh +++ b/t/t5321-pack-large-objects.sh @@ -24,7 +24,7 @@ test_expect_success 'setup' ' git index-pack --stdin