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| author | Marko Mäkelä <marko.makela@mariadb.com> | 2021-06-04 14:29:51 +0300 |
|---|---|---|
| committer | Marko Mäkelä <marko.makela@mariadb.com> | 2021-06-04 14:29:51 +0300 |
| commit | a775a3e2d83ae7d98cb0c3be48b80223437350ab (patch) | |
| tree | 6646c2cb4315b7f61687dc15adf94f2f3c6b5288 | |
| parent | 3c97097f11bf111b7b25378e0c05011849e57541 (diff) | |
| download | mariadb-git-bb-10.5-MDEV-25783.tar.gz | |
MDEV-25783: Change buffer records are lost under heavy loadbb-10.5-MDEV-25783
ibuf_read_merge_pages(): Disable some code that was added in MDEV-20394
in order to avoid a server hang if the change buffer is corrupted,
presumably due to the race condition in recovery that was later fixed in
MDEV-24449. The code will still be available in debug builds when
the command line option --debug=d,ibuf_merge_corruption is specified.
| -rw-r--r-- | storage/innobase/ibuf/ibuf0ibuf.cc | 28 |
1 files changed, 28 insertions, 0 deletions
diff --git a/storage/innobase/ibuf/ibuf0ibuf.cc b/storage/innobase/ibuf/ibuf0ibuf.cc index 3c7f2de2a67..dbe44e63522 100644 --- a/storage/innobase/ibuf/ibuf0ibuf.cc +++ b/storage/innobase/ibuf/ibuf0ibuf.cc @@ -2296,9 +2296,11 @@ bool ibuf_delete_rec(const page_id_t page_id, btr_pcur_t* pcur, static void ibuf_read_merge_pages(const uint32_t* space_ids, const uint32_t* page_nos, ulint n_stored) { +#ifndef DBUG_OFF mem_heap_t* heap = mem_heap_create(512); ulint dops[IBUF_OP_COUNT]; memset(dops, 0, sizeof(dops)); +#endif for (ulint i = 0; i < n_stored; i++) { const ulint space_id = space_ids[i]; @@ -2331,6 +2333,29 @@ tablespace_deleted: goto tablespace_deleted; } } +#ifndef DBUG_OFF + DBUG_EXECUTE_IF("ibuf_merge_corruption", goto work_around;); + continue; + + /* The following code works around a hang when the + change buffer is corrupted, likely due to the race + condition in crash recovery that was fixed in + MDEV-24449. But, it also introduces corruption by + itself in the following scenario: + + The following sequence of events is possible: + (1) We merged buffered changes in buf_page_get_gen() + (2) We committed the mini-transaction + (3) Redo log and the page with the merged changes is written + (4) A write completion callback thread evicts the page. + (5) Other threads buffer changes for that page. + (6) We will wrongly discard those newly buffered changes below. + + This code will be available in debug builds, so that + users may try to fix a shutdown hang that occurs due + to a corrupted change buffer. */ + +work_around: /* Prevent an infinite loop, by removing entries from the change buffer also in the case the bitmap bits were wrongly clear even though buffered changes exist. */ @@ -2377,10 +2402,13 @@ done: ibuf_mtr_commit(&mtr); btr_pcur_close(&pcur); mem_heap_empty(heap); +#endif } +#ifndef DBUG_OFF ibuf_add_ops(ibuf.n_discarded_ops, dops); mem_heap_free(heap); +#endif } /*********************************************************************//** |