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go nodes 0
does infinite search
#2003
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Here seems to be the problem : In the file src/mcts/stoppers/stoppers.h
For some reason when limit = 0, nodes_limit is changed to 4000000000ll which makes |
This 4'000'000'000 was introduced to prevent number of nodes overflowing uint32 (e.g. in // common.cc // "go nodes" stopper.
int64_t node_limit = 0;
if (params.nodes) {
if (options.Get<bool>(kNodesAsPlayoutsId)) {
stopper->AddStopper(std::make_unique<PlayoutsStopper>(
*params.nodes, options.Get<float>(kSmartPruningFactorId) > 0.0f));
} else {
node_limit = *params.nodes;
}
}
// always limit nodes to avoid exceeding the limit 4000000000. That number is
// default when node_limit = 0.
stopper->AddStopper(std::make_unique<VisitsStopper>(
node_limit, options.Get<float>(kSmartPruningFactorId) > 0.0f));
Also I can see that you posted a snippet from |
Indeed i confused // src/mcts/stoppers/stoppers.h // Watches visits (total tree nodes) and predicts remaining visits.
class VisitsStopper : public SearchStopper {
public:
VisitsStopper(int64_t limit, bool populate_remaining_playouts)
: nodes_limit_(limit ? limit : 4000000000ll),
populate_remaining_playouts_(populate_remaining_playouts) {}
int64_t GetVisitsLimit() const { return nodes_limit_; }
bool ShouldStop(const IterationStats&, StoppersHints*) override;
private:
const int64_t nodes_limit_;
const bool populate_remaining_playouts_;
};
But how exactly is this preventing uint32 overflow ? Since a check on 0 doesn't mean it has overflowed for more than 0 ? Or am I missing something |
If the limit is set to 0, the |
-node_limit is set to 4000000000 in the case that params.nodes is not initialized. -node_limit is set to params.nodes if params.nodes is initialized as 0 or another int as value
node_limits value now follows the value passed to the stopper in common.cc (= 4000000000 if params.nodes was not initialized, = params.nodes if params.nodes was initialized to an int, 0 included)
since GoParams.nodes is an std::optional, it's initialization status can be checked through params.nodes.has_value() instead of params.nodes, which returns false if params.nodes is set to 0 (source of the problem). I find it odd that addStopper initiated with node_limit is run outside of the 'else' block. Meaning that if params.nodes is initiated 2 stoppers, one having 0 as a node_limit are initiated. Is there a particular reason for this? |
i believe PR #2056 fixes the issue |
It should stop immediately instead (or do one iteration when the tree is empty).
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