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fix: Fix memory leak caused by asynchronous prefetch #14722

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fix: Fix memory leak caused by asynchronous prefetch #14722

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2f9ef0b
ok now !!!!
Sep 4, 2025
53f48a9
followup
Sep 4, 2025
b608a15
formatted.
Sep 4, 2025
7336360
fix
Sep 4, 2025
62b31c4
waiting until finish.
Sep 10, 2025
b37b4c8
revert
Sep 22, 2025
29d86d9
format
Sep 22, 2025
0834da1
wait only when state is loading
Sep 25, 2025
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2 changes: 1 addition & 1 deletion velox/common/caching/AsyncDataCache.h
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Original file line number Diff line number Diff line change
Expand Up @@ -446,7 +446,7 @@ class CoalescedLoad {
return state_;
}

void cancel() {
virtual void cancel() {
setEndState(State::kCancelled);
}

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3 changes: 1 addition & 2 deletions velox/dwio/common/DirectBufferedInput.cpp
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Expand Up @@ -218,8 +218,7 @@ void DirectBufferedInput::readRegions(
for (auto i = 0; i < coalescedLoads_.size(); ++i) {
auto& load = coalescedLoads_[i];
if (load->state() == CoalescedLoad::State::kPlanned) {
AsyncLoadHolder loadHolder{
.load = load, .pool = pool_->shared_from_this()};
AsyncLoadHolder loadHolder{.load = load};
executor_->add([asyncLoad = std::move(loadHolder)]() {
process::TraceContext trace("Read Ahead");
VELOX_CHECK_NOT_NULL(asyncLoad.load);
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21 changes: 11 additions & 10 deletions velox/dwio/common/DirectBufferedInput.h
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Expand Up @@ -101,6 +101,17 @@ class DirectCoalescedLoad : public cache::CoalescedLoad {
return size;
}

void cancel() override {
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@rui-mo rui-mo Oct 31, 2025

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The cancel() function is invoked by ~DirectBufferedInput(), which ultimately depends on the destructor of TableScan, as TableScan owns the std::unique_ptr<connector::DataSource> dataSource_. This dependency relationship is illustrated in this discussion. As a result, TableScan must be destroyed before the memory manager, but the current approach in this PR does not explicitly guarantee that order.

To ensure that the memory held by the load is always properly released, PR #8205 triggers close() through the TableScan::close() call chain to address the similar issue.

Would you like to share your opinions on the fixes? cc: @xiaoxmeng @FelixYBW Thanks.

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@FelixYBW FelixYBW Nov 21, 2025

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The solution is either free the resources manually from top to bottom or free it in object destruction. Either way works.

folly::SemiFuture<bool> waitFuture(false);
if (!loadOrFuture(&waitFuture)) {
waitFuture.wait();
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@xiaoxmeng xiaoxmeng Nov 23, 2025

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such wait can easily lead to deadlock in Prestissimo use case @kewang1024 @Yuhta

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@FelixYBW FelixYBW Nov 25, 2025

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Can you share more details? Let me check if Gluten has the issue or not.

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@xiaoxmeng xiaoxmeng Nov 27, 2025

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@FelixYBW I explained this offline to @rui-mo

}
for (auto& request : requests_) {
pool_->freeNonContiguous(request.data);
}
CoalescedLoad::cancel();
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@PHILO-HE PHILO-HE Sep 22, 2025

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Could you help confirm if it is better to call cancel at first?

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@j7nhai j7nhai Sep 22, 2025

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It is incorrect to call the cancel function first, because doing so will immediately set state_ to cancelled, and as a result, the loadOrFuture function will not perform any actual waiting.

}

private:
const std::shared_ptr<IoStatistics> ioStats_;
const std::shared_ptr<filesystems::File::IoStats> fsStats_;
Expand Down Expand Up @@ -243,21 +254,11 @@ class DirectBufferedInput : public BufferedInput {
bool prefetch,
const std::vector<int32_t>& groupEnds);

// Holds the reference on the memory pool for async load in case of early task
// terminate.
struct AsyncLoadHolder {
std::shared_ptr<cache::CoalescedLoad> load;
std::shared_ptr<memory::MemoryPool> pool;

~AsyncLoadHolder() {
// Release the load reference before the memory pool reference.
// This is to make sure the memory pool is not destroyed before we free up
// the allocated buffers.
// This is to handle the case that the associated task has already
// destroyed before the async load is done. The async load holds
// the last reference to the memory pool in that case.
load.reset();
pool.reset();
}
};

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