ARROW-7364: [Rust] Specialize cast_options.safe casting for performance#2
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seddonm1 merged 1 commit intoseddonm1:safe-castfrom Apr 5, 2021
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@alamb Yes, this was my next approach. I didn't realise that rust treated closures as different branches which makes the reuse of code less possible. I think this is safe to merge. |
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The issue I found was that if two branches both return types that implement |
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From a deadlocked run... ``` #0 0x00007f8a5d48dccd in __lll_lock_wait () from /lib64/libpthread.so.0 #1 0x00007f8a5d486f05 in pthread_mutex_lock () from /lib64/libpthread.so.0 #2 0x00007f8a566e7e89 in arrow::internal::FnOnce<void ()>::FnImpl<arrow::Future<Aws::Utils::Outcome<Aws::S3::Model::ListObjectsV2Result, Aws::S3::S3Error> >::Callback<arrow::fs::(anonymous namespace)::TreeWalker::ListObjectsV2Handler> >::invoke() () from /arrow/r/check/arrow.Rcheck/arrow/libs/arrow.so apache#3 0x00007f8a5650efa0 in arrow::FutureImpl::AddCallback(arrow::internal::FnOnce<void ()>) () from /arrow/r/check/arrow.Rcheck/arrow/libs/arrow.so apache#4 0x00007f8a566e67a9 in arrow::fs::(anonymous namespace)::TreeWalker::ListObjectsV2Handler::SpawnListObjectsV2() () from /arrow/r/check/arrow.Rcheck/arrow/libs/arrow.so apache#5 0x00007f8a566e723f in arrow::fs::(anonymous namespace)::TreeWalker::WalkChild(std::__cxx11::basic_string<char, std::char_traits<char>, std::allocator<char> >, int) () from /arrow/r/check/arrow.Rcheck/arrow/libs/arrow.so apache#6 0x00007f8a566e827d in arrow::internal::FnOnce<void ()>::FnImpl<arrow::Future<Aws::Utils::Outcome<Aws::S3::Model::ListObjectsV2Result, Aws::S3::S3Error> >::Callback<arrow::fs::(anonymous namespace)::TreeWalker::ListObjectsV2Handler> >::invoke() () from /arrow/r/check/arrow.Rcheck/arrow/libs/arrow.so apache#7 0x00007f8a5650efa0 in arrow::FutureImpl::AddCallback(arrow::internal::FnOnce<void ()>) () from /arrow/r/check/arrow.Rcheck/arrow/libs/arrow.so apache#8 0x00007f8a566e67a9 in arrow::fs::(anonymous namespace)::TreeWalker::ListObjectsV2Handler::SpawnListObjectsV2() () from /arrow/r/check/arrow.Rcheck/arrow/libs/arrow.so apache#9 0x00007f8a566e723f in arrow::fs::(anonymous namespace)::TreeWalker::WalkChild(std::__cxx11::basic_string<char, std::char_traits<char>, std::allocator<char> >, int) () from /arrow/r/check/arrow.Rcheck/arrow/libs/arrow.so apache#10 0x00007f8a566e74b1 in arrow::fs::(anonymous namespace)::TreeWalker::DoWalk() () from /arrow/r/check/arrow.Rcheck/arrow/libs/arrow.so ``` The callback `ListObjectsV2Handler` is being called recursively and the mutex is non-reentrant thus deadlock. To fix it I got rid of the mutex on `TreeWalker` by using `arrow::util::internal::TaskGroup` instead of manually tracking the #/status of in-flight requests. Closes apache#9842 from westonpace/bugfix/arrow-12040 Lead-authored-by: Weston Pace <[email protected]> Co-authored-by: Antoine Pitrou <[email protected]> Signed-off-by: Antoine Pitrou <[email protected]>
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@seddonm1 -- This is a proposed addition to your PR apache#9682, where we added support for
CastOptions::safeAs part of that new code, we added several calls to
collect()which means an extra copy of the data is made, as well as a check forCastOption::safefor each element.Changes
This PR improves performance by refactoring the code to use the pre
CastOptionscodepath whenCastOptions::safeis false, and the new codepath whenCastOptions::safeis trueBenchmarks:
(I am working on them)