error with node_hash_map<uint32_t, std::vector<uint32_t>> about parallel-hashmap

[HatakeKakaxi]

When I try to use phmap::parallel_node_hash_map<uint32_t, std::vector<uint32_t>>, I got nearly the same error.

[greg7mdp]

Hi @HatakeKakaxi , when using a parallel_node_hash_map from multiple threads, it is not safe to use iterators, or references returned by operator[](). If you provide a full example of what you are doing, I can suggest how to use extended APIs to solve your issue.

[HatakeKakaxi]

Hi @HatakeKakaxi , when using a parallel_node_hash_map from multiple threads, it is not safe to use iterators, or references returned by operator[](). If you provide a full example of what you are doing, I can suggest how to use extended APIs to solve your issue.

Thank you, @greg7mdp. Here is my example. I defined a phmap::parallel_node_hash_map<uint32_t, std::vector<uint32_t>> seed_index_pos in the main thread, and modify this parallel_node_hash_map in other threads. I use a boost::thread_pool with 8 threads to modify this hash map. The modication is just like this:
seed_index_pos[index].emplace_back(1);
Did you mean that it's not safe to use the operator[]() ? Which APIs should I use ?

[greg7mdp]

Did you mean that it's not safe to use the operator[]() ?

This is correct, it is not safe in a multithreaded context.

Which APIs should I use ?

You should most likely use lazy_emplace_l. Please see mt_word_counter.cc example in the examples directory.