[CBRD-26615] Reduce I/O bottleneck when parallel heap scan by xmilex-git · Pull Request #6911 · CUBRID/cubrid

xmilex-git · 2026-03-17T06:37:25Z

http://jira.cubrid.org/browse/CBRD-26615

Purpose

Parallel Heap Scan 수행 시 발생하는 I/O 병목 현상을 해소하기 위해 스캔 분배 방식을 최적화합니다.

기존 방식은 전역 Mutex를 사용하여 page_next 로직을 통해 페이지를 하나씩 순차적으로 할당받는 구조였습니다. 이로 인해 스레드가 페이지를 할당받고 I/O를 수행하는 과정에서 동기화 호출이 잦아지고, 사실상 I/O를 기다리는 시점이 직렬화되어 다중 스레드의 이점을 충분히 활용하지 못하는 병목이 존재했습니다.

이를 개선하기 위해, 스캔 시작 단계에서 Heap File의 헤더를 한 번만 읽어 전체 데이터가 포함된 Partial Sector (64페이지 단위) 정보를 미리 수집(Fetch)합니다. 수집된 섹션 정보들을 워커 스레드들에게 미리 나누어 할당함으로써, 각 스레드가 자신에게 할당된 섹터 범위를 독립적으로 순회(Iteration)하며 별도의 락 없이 병렬적으로 I/O를 발생시키고 데이터를 처리할 수 있도록 구조를 개선합니다.

Implementation

Storage - File Manager (src/storage/)

file_manager.c: file_get_all_data_sectors 함수를 추가하여 힙 파일의 PART_FTAB(일부 사용 중인 섹터)과 FULL_FTAB(꽉 찬 섹터) 정보를 모두 순회하며 실제 데이터가 포함된 섹터 정보를 FILE_FTAB_COLLECTOR로 수집하도록 구현했습니다.
file_manager.h: 섹터 수집을 위한 구조체 및 비트맵 매크로(FILE_FULL_PAGE_BITMAP 등)와 외부 인터페이스를 선언했습니다.

px_heap_scan_input_handler_ftabs.cpp:
init_on_main: 메인 스레드에서 file_get_all_data_sectors를 호출하여 전체 섹션 위치를 파악하고 병렬도에 맞춰 분할합니다.
get_next_vpid_with_fix: 할당된 섹터 내의 비트맵을 로컬 스레드에서 직접 확인하며 페이지를 pgbuf_fix 하도록 수정하여, 전역 Mutex 없이도 독립적인 I/O 발생이 가능하도록 로직을 변경했습니다.

github-actions · 2026-03-17T06:38:40Z

🧪 TC Test Environment Ready

CircleCI Testing:

CircleCI will automatically test using the branches below.

TC Repositories & Branches:

cubrid-testcases Draft PR (Branch: tc/pr-6911)
cubrid-testcases-private-ex Draft PR (Branch: tc/pr-6911)

Next Steps:

Wait for CircleCI tests to complete
If CircleCI tests failed, please check the test results and fix the issues.
When ready to merge this PR, please merge the TC PR first, then merge this PR.

xmilex-git · 2026-03-17T07:13:50Z

/run all

xmilex-git · 2026-03-17T09:53:32Z

/run all

greptile-apps · 2026-03-17T10:53:48Z

_{Last reviewed commit: f9d0b43}

greptile-apps · 2026-03-18T04:04:54Z

_{Last reviewed commit: "greptile review appl..."}

greptile-apps · 2026-03-18T04:22:29Z

_{Last reviewed commit: "greptile review appl..."}

greptile-apps · 2026-03-18T05:48:21Z

_{Last reviewed commit: "allow not-ordered pa..."}

This reverts commit f35d2ab.

xmilex-git · 2026-03-24T08:57:30Z

/run all

greptile-apps · 2026-03-24T09:02:39Z

_{Reviews (14): Last reviewed commit: "Revert "remove old page watcher"" | Re-trigger Greptile}

greptile-apps · 2026-03-25T02:01:41Z

_{Reviews (15): Last reviewed commit: "there are no miss without error code" | Re-trigger Greptile}

greptile-apps · 2026-03-25T02:13:04Z

_{Reviews (16): Last reviewed commit: "remove redundant header" | Re-trigger Greptile}

greptile-apps · 2026-03-25T04:12:27Z

_{Reviews (17): Last reviewed commit: "remove pb modification" | Re-trigger Greptile}

greptile-apps · 2026-03-26T10:24:53Z

_{Reviews (18): Last reviewed commit: "review apply" | Re-trigger Greptile}

xmilex-git · 2026-03-27T04:20:11Z

/run all

greptile-apps · 2026-03-27T05:09:02Z

_{Reviews (19): Last reviewed commit: "review apply : ykham" | Re-trigger Greptile}

xmilex-git · 2026-03-27T06:40:56Z

/run all

github-actions · 2026-03-27T07:46:42Z

✅ TC Branch Finalized for cubrid-testcases-private-ex

Engine PR was merged.

Cleanup Results:

Draft PR #3050: [CBRD-26615] Draft: TC changes for PR CUBRID/cubrid#6911: Closed
Branch tc/pr-6911: Deleted

TC base branch is ready for the next PR.

github-actions · 2026-03-27T07:46:43Z

✅ TC Branch Finalized for cubrid-testcases

Engine PR was merged.

Cleanup Results:

Draft PR #2521: [CBRD-26615] Draft: TC changes for PR CUBRID/cubrid#6911: Closed
Branch tc/pr-6911: Deleted

TC base branch is ready for the next PR.

…eap scan (CUBRID#6911)

Purpose Optimize the scan distribution method to resolve I/O bottlenecks occurring during Parallel Heap Scans. The previous implementation relied on a structure where pages were allocated sequentially one by one through page_next logic using a global Mutex. This led to frequent synchronization calls as threads attempted to allocate pages and perform I/O. Consequently, the timing of I/O waits became effectively serialized, creating a bottleneck that prevented the system from fully utilizing the advantages of multi-threading. To improve this, the Heap File header is now read only once at the start of the scan to pre-fetch Partial Sector (64-page units) information containing all data. By pre-allocating these collected sector details to worker threads, the structure is enhanced so that each thread can independently iterate through its assigned sector range. This allows for parallel I/O and data processing without additional locking. Implementation Storage - File Manager (src/storage/) file_manager.c: Added the file_get_all_data_sectors function. It iterates through both PART_FTAB (partially used sectors) and FULL_FTAB (full sectors) of the heap file to collect information on sectors containing actual data into a FILE_FTAB_COLLECTOR. file_manager.h: Declared structures and bitmap macros (e.g., FILE_FULL_PAGE_BITMAP) for sector collection, along with external interfaces. px_heap_scan_input_handler_ftabs.cpp init_on_main: The main thread calls file_get_all_data_sectors to identify all sector locations and partition them according to the degree of parallelism. get_next_vpid_with_fix: Modified the logic to allow local threads to directly check the bitmap within their assigned sectors and perform pgbuf_fix. This enables independent I/O generation without relying on a global Mutex.

xmilex-git added 3 commits March 17, 2026 13:20

initial commit : ftabset

6b746ae

fix ftab bugs..?

149d53e

input handler

9ea637f

xmilex-git self-assigned this Mar 17, 2026

cubrid-tc-sync-bot bot mentioned this pull request Mar 17, 2026

[CBRD-26615] Draft: TC changes for PR CUBRID/cubrid#6911 CUBRID/cubrid-testcases#2521

Closed

xmilex-git added 2 commits March 17, 2026 15:41

필요없는 코드 제거

21790eb

convert to read latch

3d5c511

skip heap header page

f9d0b43

xmilex-git requested review from Hamkua, HyunukLee, sohee-dgist and youngjinj March 17, 2026 10:48

xmilex-git marked this pull request as ready for review March 17, 2026 10:48

xmilex-git requested review from hornetmj and shparkcubrid as code owners March 17, 2026 10:48

greptile-apps bot reviewed Mar 17, 2026

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greptile review apply

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greptile-apps bot reviewed Mar 18, 2026

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Comment thread src/query/parallel/px_heap_scan/px_heap_scan.cpp Outdated

Comment thread src/query/parallel/px_heap_scan/px_heap_scan_input_handler_ftabs.cpp

greptile review apply

4e42b57

greptile-apps bot reviewed Mar 18, 2026

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Comment thread src/query/parallel/px_heap_scan/px_heap_scan.cpp

Comment thread src/storage/file_manager.c

Comment thread src/query/parallel/px_heap_scan/px_heap_scan_input_handler_ftabs.cpp Outdated

Comment thread src/storage/file_manager.c

allow not-ordered page (e.g. PAGE_FTAB)

aa3f1f9

greptile-apps bot reviewed Mar 18, 2026

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Comment thread src/storage/page_buffer.c Outdated

greptile review apply3

0cc87db

Revert "remove old page watcher"

5220a99

This reverts commit f35d2ab.

xmilex-git added 2 commits March 25, 2026 10:51

replace page type check to assert

755f474

there are no miss without error code

5f2911e

remove redundant header

8cc13ab

remove pb modification

d41c868

shparkcubrid approved these changes Mar 25, 2026

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youngjinj reviewed Mar 26, 2026

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Comment thread src/storage/file_manager.c Outdated

youngjinj reviewed Mar 26, 2026

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Comment thread src/storage/file_manager.c

review apply

e03024c

sohee-dgist approved these changes Mar 27, 2026

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review apply : ykham

e75014a

Hamkua approved these changes Mar 27, 2026

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youngjinj approved these changes Mar 27, 2026

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HyunukLee approved these changes Mar 27, 2026

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xmilex-git merged commit 45730b9 into CUBRID:develop Mar 27, 2026
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hyunikn added a commit to hyunikn/cubrid that referenced this pull request Mar 27, 2026

for commit 45730b9 [CBRD-26615] Reduce I/O bottleneck when parallel h…

6721f27

…eap scan (CUBRID#6911)

hyunikn added a commit to hyunikn/cubrid that referenced this pull request Mar 27, 2026

for commit 45730b9 [CBRD-26615] Reduce I/O bottleneck when parallel h…

50fae3a

…eap scan (CUBRID#6911)

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xmilex-git commented Mar 17, 2026

Purpose

Implementation

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