Need help for error: Assertion `this->load_steals() == 0' failed

[Frandy]

I'm trying to use libfork for dag task, and got below code. It can get the correct output, but got assert error before exit. It is ok if with unit_pool.
Would you please give some help ?

build command
g++-14 test2.cpp -std=c++2b -I/usr/local/include/libfork-3.8.0/ -o test2

test2.cpp

#include <atomic>
#include <libfork.hpp>
#include <print>
#include <string>
#include <vector>

struct TaskNode {
    TaskNode(const std::string &name) : name(name) {}
    void execute() { std::println("executing task {}", name); }
    std::string name;
    std::vector<TaskNode *> dependencies;
    std::vector<TaskNode *> successors;
    std::atomic<int> remaining_dependencies{0};
};

inline constexpr auto process_node = [](auto process_node,
                                        TaskNode *node) -> lf::task<> {
    node->execute();

    for (TaskNode *successor : node->successors) {
        int previous = successor->remaining_dependencies.fetch_sub(
            1, std::memory_order_acq_rel);

        if (previous == 1) {
            co_await lf::fork(process_node)(successor);
        }
    }
};

inline constexpr auto run_dag =
    [](auto run_dag, std::vector<TaskNode *> &entries) -> lf::task<> {
    for (TaskNode *entry : entries) {
        co_await lf::fork(process_node)(entry);
    }
    // co_await lf::join();
};

int main() {
    TaskNode a("a"), b("b"), c("c"), d("d"), e("e");

    a.successors = {&b};

    b.dependencies = {&a};
    b.successors = {&c};

    c.dependencies = {&b};

    d.successors = {&e};
    e.dependencies = {&d};

    for (TaskNode *node : {&a, &b, &c, &d, &e}) {
        node->remaining_dependencies.store(node->dependencies.size(),
                                           std::memory_order_relaxed);
    }

    std::vector<TaskNode *> entries;
    for (TaskNode *node : {&a, &b, &c, &d, &e}) {
        if (node->remaining_dependencies.load(std::memory_order_relaxed) == 0) {
            entries.push_back(node);
        }
    }

    lf::lazy_pool pool(2);
    // lf::unit_pool pool;

    lf::sync_wait(pool, run_dag, entries);

    return 0;
}

the output as below
executing task d
executing task e
executing task a
executing task b
executing task c
test2: /usr/local/include/libfork-3.8.0/libfork/core/impl/promise.hpp:308: auto lf::impl::promise<R, I, Tag>::final_suspend() const [with R = void; I = std::shared_ptr<lf::impl::future_shared_state >; lf::core::tag Tag = lf::core::tag::root]: Assertion `this->load_steals() == 0' failed.
Aborted (core dumped)

[ConorWilliams]

It looks like you have no joins, every fork requires a join.

Also libfork provides a for_each primitive that will get you better performance than this

[Frandy]

It looks like you have no joins, every fork requires a join.

Also libfork provides a for_each primitive that will get you better performance than this

Thanks for your reply. now I added two lf::join , but got below compile error.
new add code as below

error

test2.cpp: In lambda function:
test2.cpp:28:22: error: no match for call to ‘(const lf::impl::join_type) ()’
   28 |     co_await lf::join();
      |              ~~~~~~~~^~
test2.cpp: In lambda function:
test2.cpp:34:26: warning: ‘static auto lf::impl::bind_task<Tag, Mod>::operator()(F&&) [with F = const<lambda(auto:86, TaskNode*)>&; lf::core::tag Tag = lf::core::tag::fork; Mod = lf::core::modifier::none]’ is deprecated: Use operator[] instead of operator() [-Wdeprecated-declarations]
   34 |         co_await lf::fork(process_node)(entry);
      |                  ~~~~~~~~^~~~~~~~~~~~~~
In file included from /usr/local/include/libfork-3.8.0/libfork/core.hpp:13:
/usr/local/include/libfork-3.8.0/libfork/core/control_flow.hpp:82:55: note: declared here
   82 |   LF_DEPRECATE_CALL [[nodiscard]] LF_STATIC_CALL auto operator()(F &&fun) LF_STATIC_CONST {
      |                                                       ^~~~~~~~
test2.cpp:34:26: warning: ‘static auto lf::impl::bind_task<Tag, Mod>::operator()(F&&) [with F = const<lambda(auto:86, TaskNode*)>&; lf::core::tag Tag = lf::core::tag::fork; Mod = lf::core::modifier::none]’ is deprecated: Use operator[] instead of operator() [-Wdeprecated-declarations]
   34 |         co_await lf::fork(process_node)(entry);
      |                  ~~~~~~~~^~~~~~~~~~~~~~
/usr/local/include/libfork-3.8.0/libfork/core/control_flow.hpp:82:55: note: declared here
   82 |   LF_DEPRECATE_CALL [[nodiscard]] LF_STATIC_CALL auto operator()(F &&fun) LF_STATIC_CONST {
      |                                                       ^~~~~~~~
test2.cpp:36:22: error: no match for call to ‘(const lf::impl::join_type) ()’
   36 |     co_await lf::join();
      |              ~~~~~~~~^~

[ConorWilliams]

Join is an object that can be directly awaited you don't need the parentheses

[Frandy]

Join is an object that can be directly awaited you don't need the parentheses

Yeah！
Thank you very much.