Fix occasional segmentation fault in git gc
#1853
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Signed-off-by: Johannes Schindelin <[email protected]>
There is a problem in the way 9ac3f0e (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 git-for-windows#1839. Signed-off-by: Johannes Schindelin <[email protected]>
…spot In 9ac3f0e (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 git-for-windows#1839. Signed-off-by: Johannes Schindelin <[email protected]>
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Sep 27, 2018
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Oct 10, 2018
Fix occasional segmentation fault in `git gc`
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Oct 11, 2018
Fix occasional segmentation fault in `git gc`
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Nov 19, 2018
Fix occasional segmentation fault in `git gc`
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It was reported in #1839 that
git gccrashes under certain circumstances. The MCVE provided by @thomas-patzig and the initial analysis by @kgybels were invaluable to come up with this PR. Thank you!