[Enhancement] use stream load async return to optimize the performance under high concurrency #53144
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added 3 commits
July 12, 2025 12:04
…e better http performance * fix some bug for partition * fix for thrift * fix the thrift exit bug * Revert "[feat](http): use async reply to provide better http performance * ensure free order * [Fix](stream-load) Fix stream load stuck under high concurrency (apache#36772) When the concurrency of streamload exceeds the number of threads in the remote scanner, streamload may get stuck. The reason is that the libevent thread blocks and waits for streamload to complete, and when there is no intersection between the tasks handled by the scanner thread and the libevent thread, it gets stuck. The solution is to convert the synchronous waiting tasks of libevent into asynchronous execution by using callbacks in the streamload executor thread. See merge request: !740" Revert commit d9e74efa762c8161a5ca3df4290bbd0ab896f1ef See merge request: !745" Revert commit 396cb2ec7e0b1a21bc0d7424c627f0d9321884bc
* fix missing ; * fix stream load block See merge request: !855
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gavinchou
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Jul 14, 2025
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| int StreamLoadAction::on_header(HttpRequest* req) { | ||
| req->mark_send_reply(); |
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只有 StreamLoad 请求，另外只是提交 reply 是 async 的，客户端感知仍然是同步的。
gavinchou
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Jul 14, 2025
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| SendReplyType _send_reply_type = REPLY_SYNC; |
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这个初始值是不是没啥用 因为 on_header 把它改写了
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还有其他 HttpAction 会用到，他们需要默认是 SYNC 的。
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added 4 commits
July 15, 2025 10:55
…e better http performance * fix some bug for partition * fix for thrift * fix the thrift exit bug * Revert "[feat](http): use async reply to provide better http performance * ensure free order * [Fix](stream-load) Fix stream load stuck under high concurrency (apache#36772) When the concurrency of streamload exceeds the number of threads in the remote scanner, streamload may get stuck. The reason is that the libevent thread blocks and waits for streamload to complete, and when there is no intersection between the tasks handled by the scanner thread and the libevent thread, it gets stuck. The solution is to convert the synchronous waiting tasks of libevent into asynchronous execution by using callbacks in the streamload executor thread. See merge request: !740" Revert commit d9e74efa762c8161a5ca3df4290bbd0ab896f1ef See merge request: !745" Revert commit 396cb2ec7e0b1a21bc0d7424c627f0d9321884bc
* fix missing ; * fix stream load block See merge request: !855
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TPC-H: Total hot run time: 32001 ms |
TPC-DS: Total hot run time: 173277 ms |
ClickBench: Total hot run time: 27.01 s |
BE UT Coverage ReportIncrement line coverage Increment coverage report
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dataroaring
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Jan 5, 2026
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Code Review: Stream Load Async Return Optimization
Thanks for this PR! The optimization concept is sound - making HTTP replies asynchronous should improve thread utilization under high concurrency. I've traced through the synchronization logic and verified it handles race conditions correctly.
Critical Issues (Please Fix Before Merge)
1. Typo in Variable Name (http_request.h:108)
std::future<bool> _http_reply_futrue = _http_reply_promise.get_future();
// ^^^^^^ should be "future"2. Hardcoded 3-Second Timeout (http_request.cpp:175)
auto status = _http_reply_futrue.wait_for(std::chrono::seconds(3));3 seconds is too aggressive for legitimate long-running loads. Consider:
- Making it configurable via
config::stream_load_async_reply_timeout_s - Default to something like 300 seconds
3. Debug Stack Trace Logging (http_request.cpp:159)
VLOG_NOTICE << "finish send reply, infos=" << infos
<< ", stack=" << get_stack_trace(); // temp locate problemget_stack_trace()is expensive even when VLOG is disabled (string is still constructed)- Comment says "temp locate problem" - should be removed before merge
Minor Issues
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Duplicate error logging - Same error logged in both
handle()(line 122) and_send_reply()(line 157) -
Missing
finish_send_reply()insend_error()-http_channel.cppcallsfinish_send_reply()insend_reply()andsend_file()but not insend_error(). Is this intentional? -
Suggestion for
is_prepare_success- Usingshared_ptr<bool>works butstd::atomic<bool>would make the intent clearer -
Consider adding comments - The synchronization state machine with
_can_send_reply,_finish_send_reply, and the CV is correct but complex. Comments explaining the wait conditions would help future maintainers.
Thread Safety Analysis ✅
I traced through these scenarios and verified the logic is correct:
| Scenario | Result |
|---|---|
| Normal success path | ✅ Reply sent via callback |
on_header failure |
✅ Reply sent immediately, handle() skipped |
| Fragment prepare failure | ✅ Callback not invoked, handle() sends reply |
| Request timeout | ✅ _finish_send_reply=true prevents use-after-free |
Overall
Concept: ✅ Sound optimization approach
Implementation:
Thread Safety: ✅ Correct
Recommend addressing the 3 critical issues before merge.
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Follow-up on After deeper investigation, this is NOT a bug. Here's why:
Therefore, |
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is_prepare_success must use std::shared_ptr |
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TPC-H: Total hot run time: 31474 ms |
TPC-DS: Total hot run time: 173067 ms |
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0AyanamiRei
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Jan 12, 2026
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Jan 14, 2026
…e under high concurrency (#53144) Issue Number: close #53139 Co-authored-by: 曹俊辉 <[email protected]> Co-authored-by: Yongqiang YANG <[email protected]>
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What problem does this PR solve?
Issue Number: close #53139
Problem Summary:
Release note
use stream load async return to optimize the performance under high concurrency, we treat
send_replyas callback of exec_plan_framgnet .is_prepare_successto ensure no dead lock aton_header.ctx-> _finish_send_replyensure send_reply only be invoke one time and request is valid. becuase we can't decide if callback will send_reply again when load fail or load timeout.ctx-> _can_send_replyensure send_reply only whenon_headerfail orhandlefinished, or sender will receive broken-pipe when meet data-quality errorCheck List (For Author)
Test
Behavior changed:
Does this need documentation?
Check List (For Reviewer who merge this PR)