From 2be165b29115cfec336f5b26a098d3f041be6a8f Mon Sep 17 00:00:00 2001 From: Mike Kolupaev Date: Thu, 25 Aug 2016 04:39:26 -0700 Subject: [PATCH] Fix a crash when compaction fails to open a file Summary: We've got a crash with this stack trace: Program terminated with signal SIGTRAP, Trace/breakpoint trap. #0 0x00007fc85f2f4009 in raise () from /usr/local/fbcode/gcc-4.9-glibc-2.20-fb/lib/libpthread.so.0 #1 0x00000000005c8f61 in facebook::logdevice::handle_sigsegv(int) () at logdevice/server/sigsegv.cpp:159 #2 0x00007fc85f2f4150 in () at /usr/local/fbcode/gcc-4.9-glibc-2.20-fb/lib/libpthread.so.0 #3 0x00000000031ed80c in rocksdb::NewReadaheadRandomAccessFile() at util/file_reader_writer.cc:383 #4 0x00000000031ed80c in rocksdb::NewReadaheadRandomAccessFile() at util/file_reader_writer.cc:472 #5 0x00000000031558e7 in rocksdb::TableCache::GetTableReader() at db/table_cache.cc:99 #6 0x0000000003156329 in rocksdb::TableCache::NewIterator() at db/table_cache.cc:198 #7 0x0000000003166568 in rocksdb::VersionSet::MakeInputIterator() at db/version_set.cc:3345 #8 0x000000000324a94f in rocksdb::CompactionJob::ProcessKeyValueCompaction(rocksdb::CompactionJob::SubcompactionState*) () at db/compaction_job.cc:650 #9 0x000000000324c2f6 in rocksdb::CompactionJob::Run() () at db/compaction_job.cc:530 #10 0x00000000030f5ae5 in rocksdb::DBImpl::BackgroundCompaction() at db/db_impl.cc:3269 #11 0x0000000003108d36 in rocksdb::DBImpl::BackgroundCallCompaction(void*) () at db/db_impl.cc:2970 #12 0x00000000029a2a9a in facebook::logdevice::RocksDBEnv::callback(void*) () at logdevice/server/locallogstore/RocksDBEnv.cpp:26 #13 0x00000000029a2a9a in facebook::logdevice::RocksDBEnv::callback(void*) () at logdevice/server/locallogstore/RocksDBEnv.cpp:30 #14 0x00000000031e7521 in rocksdb::ThreadPool::BGThread() at util/threadpool.cc:230 #15 0x00000000031e7663 in rocksdb::BGThreadWrapper(void*) () at util/threadpool.cc:254 #16 0x00007fc85f2ea7f1 in start_thread () at /usr/local/fbcode/gcc-4.9-glibc-2.20-fb/lib/libpthread.so.0 #17 0x00007fc85e8fb46d in clone () at /usr/local/fbcode/gcc-4.9-glibc-2.20-fb/lib/libc.so.6 From looking at the code, probably what happened is this: - `TableCache::GetTableReader()` called `Env::NewRandomAccessFile()`, which dispatched to a `PosixEnv::NewRandomAccessFile()`, where probably an `open()` call failed, so the `NewRandomAccessFile()` left a nullptr in the resulting file, - `TableCache::GetTableReader()` called `NewReadaheadRandomAccessFile()` with that `nullptr` file, - it tried to call file's method and crashed. This diff is a trivial fix to this crash. Test Plan: `make -j check` Reviewers: sdong, andrewkr, IslamAbdelRahman Reviewed By: IslamAbdelRahman Subscribers: andrewkr, dhruba Differential Revision: https://reviews.facebook.net/D62451 --- db/table_cache.cc | 6 +++--- 1 file changed, 3 insertions(+), 3 deletions(-) diff --git a/db/table_cache.cc b/db/table_cache.cc index 5352309f4..ff7997566 100644 --- a/db/table_cache.cc +++ b/db/table_cache.cc @@ -95,11 +95,11 @@ Status TableCache::GetTableReader( unique_ptr file; Status s = ioptions_.env->NewRandomAccessFile(fname, &file, env_options); - if (readahead > 0) { - file = NewReadaheadRandomAccessFile(std::move(file), readahead); - } RecordTick(ioptions_.statistics, NO_FILE_OPENS); if (s.ok()) { + if (readahead > 0) { + file = NewReadaheadRandomAccessFile(std::move(file), readahead); + } if (!sequential_mode && ioptions_.advise_random_on_open) { file->Hint(RandomAccessFile::RANDOM); }