LoadTableHandlers can cause std::terminate

[Ignition]

#2  0x000055a53cb70c3a in __cxxabiv1::__terminate(void (*)()) ()
#3  0x000055a53cb70ca5 in std::terminate() ()
#4  0x000055a53c768a81 in std::vector<std::thread, std::allocator<std::thread> >::~vector() ()
#5  0x000055a53c8f3d3a in rocksdb::VersionBuilder::Rep::LoadTableHandlers(rocksdb::InternalStats*, int, bool, bool, std::shared_ptr<rocksdb::SliceTransform const> const&, unsigned long) ()

Relevant code

std::vector<port::Thread> threads;
for (int i = 1; i < max_threads; i++) {
  threads.emplace_back(load_handlers_func);
}
load_handlers_func();
for (auto& t : threads) {
  t.join();
}

As far as I can tell either an exception came from emplace_back or from load_handlers_func. But in either case it caused the std::thread's destructor to have an issue because it wasn't joined yet and hence std::terminate was called.

std::thread::~thread If *this has an associated thread (joinable() == true), std::terminate() is called.

[Ignition]

Also unrelated observation, maybe worth adding if (files_meta.empty()) return Status::OK(); before making any worker threads.

[jowlyzhang]

RocksDB doesn't throw Exceptions or handle exceptions, see https://github.com/facebook/rocksdb/wiki/RocksDB-FAQ#failure-handling (mostly). Most customizable interfaces' documentation will have notes like this:

rocksdb/include/rocksdb/compaction_filter.h

Lines 51 to 53 in 62531da

	// * Exceptions MUST NOT propagate out of overridden functions into RocksDB,
	// because RocksDB is not exception-safe. This could cause undefined behavior
	// including data loss, unreported corruption, deadlocks, and more.

[Ignition]

@jowlyzhang this is not via customizable interface.

This is purely an internal correctness detail within RocksDB.

This is just standard C++. You are using std::vector::emplace_back without any custom allocator, hence it calls operator new which can throw at least std::bad_alloc (additional exceptions are allowed to be throw cause operator new can be replaced). And then it tries to destroy std::vector and hence it destroys its std::threads which will std::terminate because it wasn't joined.

Unintentionally calling std::terminate and killing the whole program should be considered a critical bug.