From 976978687e56ecd56d1a52ec1a62f0fc07032a56 Mon Sep 17 00:00:00 2001 From: Alessandro Vetere Date: Tue, 14 Apr 2026 15:38:10 +0200 Subject: [PATCH] MDEV-37070 Expose AHI disable bug --- .../innodb_buffer_pool_resize_ahi_race.result | 27 ++++++++ .../t/innodb_buffer_pool_resize_ahi_race.opt | 1 + .../t/innodb_buffer_pool_resize_ahi_race.test | 63 +++++++++++++++++++ storage/innobase/buf/buf0buf.cc | 1 + 4 files changed, 92 insertions(+) create mode 100644 mysql-test/suite/innodb/r/innodb_buffer_pool_resize_ahi_race.result create mode 100644 mysql-test/suite/innodb/t/innodb_buffer_pool_resize_ahi_race.opt create mode 100644 mysql-test/suite/innodb/t/innodb_buffer_pool_resize_ahi_race.test diff --git a/mysql-test/suite/innodb/r/innodb_buffer_pool_resize_ahi_race.result b/mysql-test/suite/innodb/r/innodb_buffer_pool_resize_ahi_race.result new file mode 100644 index 00000000000..c06474d0049 --- /dev/null +++ b/mysql-test/suite/innodb/r/innodb_buffer_pool_resize_ahi_race.result @@ -0,0 +1,27 @@ +SET @save_size= @@GLOBAL.innodb_buffer_pool_size; +SET @save_ahi= @@GLOBAL.innodb_adaptive_hash_index; +SET GLOBAL innodb_adaptive_hash_index= ON; +SET GLOBAL innodb_buffer_pool_size= 16777216; +SET GLOBAL innodb_max_purge_lag_wait= 0; +SET @save_pct= @@GLOBAL.innodb_max_dirty_pages_pct; +SET @save_pct_lwm= @@GLOBAL.innodb_max_dirty_pages_pct_lwm; +SET GLOBAL innodb_max_dirty_pages_pct_lwm= 0.0; +SET GLOBAL innodb_max_dirty_pages_pct= 0.0; +connect con1,localhost,root; +SET DEBUG_SYNC='buf_pool_resize_before_ahi_reenable SIGNAL shrink_done WAIT_FOR continue_resize'; +SET GLOBAL innodb_buffer_pool_size= 8388608; +connection default; +SET DEBUG_SYNC= 'now WAIT_FOR shrink_done'; +SET GLOBAL innodb_adaptive_hash_index= OFF; +SET DEBUG_SYNC= 'now SIGNAL continue_resize'; +connection con1; +disconnect con1; +connection default; +SELECT @@GLOBAL.innodb_adaptive_hash_index; +@@GLOBAL.innodb_adaptive_hash_index +1 +SET DEBUG_SYNC= RESET; +SET GLOBAL innodb_max_dirty_pages_pct= @save_pct; +SET GLOBAL innodb_max_dirty_pages_pct_lwm= @save_pct_lwm; +SET GLOBAL innodb_adaptive_hash_index= @save_ahi; +SET GLOBAL innodb_buffer_pool_size= @save_size; diff --git a/mysql-test/suite/innodb/t/innodb_buffer_pool_resize_ahi_race.opt b/mysql-test/suite/innodb/t/innodb_buffer_pool_resize_ahi_race.opt new file mode 100644 index 00000000000..95f86e59920 --- /dev/null +++ b/mysql-test/suite/innodb/t/innodb_buffer_pool_resize_ahi_race.opt @@ -0,0 +1 @@ +--innodb-buffer-pool-size-max=16m diff --git a/mysql-test/suite/innodb/t/innodb_buffer_pool_resize_ahi_race.test b/mysql-test/suite/innodb/t/innodb_buffer_pool_resize_ahi_race.test new file mode 100644 index 00000000000..a137d60171c --- /dev/null +++ b/mysql-test/suite/innodb/t/innodb_buffer_pool_resize_ahi_race.test @@ -0,0 +1,63 @@ +--source include/have_innodb.inc +--source include/have_debug.inc +--source include/have_debug_sync.inc + +# +# Test race condition: user disabling AHI while buffer pool shrink is +# completing should be respected. +# +# Sequence: +# 1. Thread 1 (resize): disables AHI, shrinks buffer pool successfully +# 2. Thread 2 (user): SET GLOBAL innodb_adaptive_hash_index = OFF +# 3. Thread 1 (resize): re-enables AHI unconditionally (ignoring user) +# +# Bug: resize captures ahi_disabled=true before the shrink and calls +# btr_search.enable(true) after it completes. If the user concurrently +# sets AHI=OFF, btr_search.disable() is a no-op (already disabled by +# resize), but enable(true) still fires, overriding the user's choice. +# + +SET @save_size= @@GLOBAL.innodb_buffer_pool_size; +SET @save_ahi= @@GLOBAL.innodb_adaptive_hash_index; + +SET GLOBAL innodb_adaptive_hash_index= ON; +SET GLOBAL innodb_buffer_pool_size= 16777216; + +# Flush dirty pages so the shrink can succeed +SET GLOBAL innodb_max_purge_lag_wait= 0; +SET @save_pct= @@GLOBAL.innodb_max_dirty_pages_pct; +SET @save_pct_lwm= @@GLOBAL.innodb_max_dirty_pages_pct_lwm; +SET GLOBAL innodb_max_dirty_pages_pct_lwm= 0.0; +SET GLOBAL innodb_max_dirty_pages_pct= 0.0; + +# Thread 1: begin buffer pool shrink; pause just before AHI re-enable +connect con1,localhost,root; +SET DEBUG_SYNC='buf_pool_resize_before_ahi_reenable SIGNAL shrink_done WAIT_FOR continue_resize'; +send SET GLOBAL innodb_buffer_pool_size= 8388608; + +connection default; +SET DEBUG_SYNC= 'now WAIT_FOR shrink_done'; + +# Thread 2: user explicitly disables AHI while resize is in progress. +# At this point AHI is already internally disabled by the resize thread, +# so btr_search.disable() is a no-op — but the user's intent is OFF. +SET GLOBAL innodb_adaptive_hash_index= OFF; + +# Let resize thread continue — it will call btr_search.enable(true) +SET DEBUG_SYNC= 'now SIGNAL continue_resize'; + +connection con1; +reap; +disconnect con1; + +connection default; +# Bug: the user set AHI to OFF, but resize re-enabled it. +# Expected (after fix): 0 (OFF) +# Current (bug): 1 (ON) +SELECT @@GLOBAL.innodb_adaptive_hash_index; + +SET DEBUG_SYNC= RESET; +SET GLOBAL innodb_max_dirty_pages_pct= @save_pct; +SET GLOBAL innodb_max_dirty_pages_pct_lwm= @save_pct_lwm; +SET GLOBAL innodb_adaptive_hash_index= @save_ahi; +SET GLOBAL innodb_buffer_pool_size= @save_size; diff --git a/storage/innobase/buf/buf0buf.cc b/storage/innobase/buf/buf0buf.cc index ed078d91bed..83c367c4c3d 100644 --- a/storage/innobase/buf/buf0buf.cc +++ b/storage/innobase/buf/buf0buf.cc @@ -2068,6 +2068,7 @@ ATTRIBUTE_COLD void buf_pool_t::resize(size_t size, THD *thd) noexcept } #ifdef BTR_CUR_HASH_ADAPT + DEBUG_SYNC_C("buf_pool_resize_before_ahi_reenable"); if (ahi_disabled) btr_search.enable(true); #endif -- 2.53.0