| Bug #79784 | update setup_instruments do not affect the global mutex/rwlock/cond | ||
|---|---|---|---|
| Submitted: | 28 Dec 2015 6:50 | Modified: | 21 Jan 2016 15:06 |
| Reporter: | zhang yingqiang (OCA) | Email Updates: | |
| Status: | Closed | Impact on me: | |
| Category: | MySQL Server: Performance Schema | Severity: | S3 (Non-critical) |
| Version: | 5.6.24 5.7.10 | OS: | Any |
| Assigned to: | Marc ALFF | CPU Architecture: | Any |
| Tags: | Performance Schema; global mutex; | ||
[8 Jan 2016 12:36]
MySQL Verification Team
Hello zhang yingqiang, Thank you for the report and contribution. Thanks, Umesh
[8 Jan 2016 12:36]
MySQL Verification Team
-- 5.7.10 src build -- [umshastr@hod03]/export/umesh/server/source/bugs/79784/mysql-5.7.10/mysql-test: ./mtr ps_global Logging: ./mtr ps_global MySQL Version 5.7.10 Checking supported features... - SSL connections supported - binaries are debug compiled Collecting tests... Removing old var directory... Creating var directory '/export/umesh/server/source/bugs/79784/mysql-5.7.10/mysql-test/var'... Installing system database... ============================================================================== TEST RESULT TIME (ms) or COMMENT -------------------------------------------------------------------------- worker[1] Using MTR_BUILD_THREAD 300, with reserved ports 13000..13009 update performance_schema.setup_instruments set ENABLED='yes', TIMED='yes'; set DEBUG_SYNC='after_LOCK_uuid_generator WAIT_FOR continue'; select uuid();; select uuid();; show processlist; Id User Host db Command Time State Info 3 root localhost test Query 0 starting show processlist 4 root localhost test Query 1 debug sync point: after_LOCK_uuid_generator select uuid() 5 root localhost test Query 1 executing select uuid() select * from performance_schema.events_waits_current order by THREAD_ID desc limit 1; THREAD_ID EVENT_ID END_EVENT_ID EVENT_NAME SOURCE TIMER_START TIMER_END TIMER_WAIT SPINS OBJECT_SCHEMA OBJECT_NAME INDEX_NAME OBJECT_TYPE OBJECT_INSTANCE_BEGIN NESTING_EVENT_ID NESTING_EVENT_TYPE OPERATION NUMBER_OF_BYTES FLAGS 26 23 23 wait/synch/mutex/sql/THD::LOCK_query_plan sql_class.h:1636 660349105508 660349290788 185280 NULL NULL NULL NULL NULL 139879367317872 22STAGE lock NULL NULL set DEBUG_SYNC='now signal continue'; update performance_schema.setup_instruments set ENABLED='no', TIMED='no'; uuid() 1c77f3e1-b601-11e5-9b4d-0010e05f3e06 uuid() 1c77f370-b601-11e5-9b4d-0010e05f3e06 main.ps_global [ pass ] 1019 -------------------------------------------------------------------------- The servers were restarted 0 times Spent 1.019 of 7 seconds executing testcases Completed: All 1 tests were successful. -- with suggested patch [umshastr@hod03]/export/umesh/server/source/bugs/79784/mysql-5.7.10/mysql-test: ./mtr ps_global Logging: ./mtr ps_global MySQL Version 5.7.10 Checking supported features... - SSL connections supported - binaries are debug compiled Collecting tests... Checking leftover processes... Removing old var directory... Creating var directory '/export/umesh/server/source/bugs/79784/mysql-5.7.10/mysql-test/var'... Installing system database... ============================================================================== TEST RESULT TIME (ms) or COMMENT -------------------------------------------------------------------------- worker[1] Using MTR_BUILD_THREAD 300, with reserved ports 13000..13009 update performance_schema.setup_instruments set ENABLED='yes', TIMED='yes'; set DEBUG_SYNC='after_LOCK_uuid_generator WAIT_FOR continue'; select uuid();; select uuid();; show processlist; Id User Host db Command Time State Info 3 root localhost test Query 0 starting show processlist 4 root localhost test Query 1 debug sync point: after_LOCK_uuid_generator select uuid() 5 root localhost test Query 1 executing select uuid() select * from performance_schema.events_waits_current order by THREAD_ID desc limit 1; THREAD_ID EVENT_ID END_EVENT_ID EVENT_NAME SOURCE TIMER_START TIMER_END TIMER_WAIT SPINS OBJECT_SCHEMA OBJECT_NAME INDEX_NAME OBJECT_TYPE OBJECT_INSTANCE_BEGIN NESTING_EVENT_ID NESTING_EVENT_TYPE OPERATION NUMBER_OF_BYTES FLAGS 26 42 NULL wait/synch/mutex/sql/LOCK_uuid_generator item_strfunc.cc:5089 683659714216 1686893934440 1003234220224 NULL NULL NULL NULL NULL 46456480 41 STAGE lock NULL NULL set DEBUG_SYNC='now signal continue'; update performance_schema.setup_instruments set ENABLED='no', TIMED='no'; uuid() cf009d16-b603-11e5-97ba-0010e05f3e06 uuid() cf009c73-b603-11e5-97ba-0010e05f3e06 main.ps_global [ pass ] 1023 -------------------------------------------------------------------------- The servers were restarted 0 times Spent 1.023 of 8 seconds executing testcases Completed: All 1 tests were successful.
[21 Jan 2016 15:06]
Paul DuBois
Noted in 5.7.12, 5.8.0 changelogs. Some Performance Schema global instruments, if not enabled at server startup, could be in a state where it was not possible to enable them at runtime. This restriction has been lifted. Affected instruments include mutex, rwlock, cond, and socket instances. Thanks to Zhang Yingqiang for the patch.
Description: Switch on instruments of performance schema dynamically by update table 'performance_schema.setup_instruments' without startup parameter '--performance-schema-instrument' or my.cnf, do not affect the global mutex/rwlock/cond. If we startup with "performance_schema=1 and performance_schema_instrument = '%=off' ", mysqld will set that->m_psi to NULL because klass->m_enabled is false in INIT_BODY_V1. The call stack is my_thread_global_reinit/init_thread_environment/... -> inline_mysql_mutex_init/inline_mysql_rwlock_init/...-> init_mutex_v1/init_rwlock_v1/... -> INIT_BODY_V1 . If we switch on instruments by update table 'performance_schema.setup_instruments' after that, the function table_setup_instruments::update_row_values do not create the m_psi for these global mutex/rwlock that already created, and we cannot monitor these waits in the consumer tables such as mutex_instances or events_waits_summary_by_thread_by_event_name etc. How to repeat: We take LOCK_uuid_generator as example. The debug sync patch: diff --git a/sql/item_strfunc.cc b/sql/item_strfunc.cc index 0e44416..9a810f3 100644 --- a/sql/item_strfunc.cc +++ b/sql/item_strfunc.cc @@ -4289,6 +4289,7 @@ String *Item_func_uuid::val_str(String *str) THD *thd= current_thd; mysql_mutex_lock(&LOCK_uuid_generator); + DEBUG_SYNC_C("after_LOCK_uuid_generator"); if (! uuid_time) /* first UUID() call. initializing data */ { ulong tmp=sql_rnd_with_mutex(); the mtr script ptach: diff --git a/mysql-test/t/ps_global-master.opt b/mysql-test/t/ps_global-master.opt new file mode 100644 index 0000000..b74e03b --- /dev/null +++ b/mysql-test/t/ps_global-master.opt @@ -0,0 +1 @@ +--performance-schema-instrument='%=off' diff --git a/mysql-test/t/ps_global.test b/mysql-test/t/ps_global.test new file mode 100644 index 0000000..e74cb3a --- /dev/null +++ b/mysql-test/t/ps_global.test @@ -0,0 +1,27 @@ +--source include/have_debug_sync.inc +update performance_schema.setup_instruments set ENABLED='yes', TIMED='yes'; +connect (con1,localhost,root,,); +connect (con2,localhost,root,,); + +connection con1; +set DEBUG_SYNC='after_LOCK_uuid_generator WAIT_FOR continue'; +--send select uuid(); + +connection con2; +--send select uuid(); + + +connection default; +--sleep 1 +show processlist; +# expect LOCK_uuid_generator +select * from performance_schema.events_waits_current order by THREAD_ID desc limit 1; +set DEBUG_SYNC='now signal continue'; + +update performance_schema.setup_instruments set ENABLED='no', TIMED='no'; + +connection con2; +--reap + +connection con1; +--reap Suggested fix: In my opinion, we should initialize the mysql_mutex_t::m_psi if performance_schema=1 (even if performance_schema_instrument = '%=off'). For performance reasons, we could do this to the global mutex/rwlock/cond. diff --git a/storage/perfschema/pfs.cc b/storage/perfschema/pfs.cc index 072bb9f..3ccea69 100644 --- a/storage/perfschema/pfs.cc +++ b/storage/perfschema/pfs.cc @@ -1477,7 +1477,7 @@ static void register_socket_v1(const char *category, klass= find_##T##_class(KEY); \ if (unlikely(klass == NULL)) \ return NULL; \ - if (! klass->m_enabled) \ + if (! pfs_param.m_enabled) \ return NULL; \ pfs= create_##T(klass, ID); \ return reinterpret_cast<PSI_##T *> (pfs) diff --git a/storage/perfschema/pfs_server.cc b/storage/perfschema/pfs_server.cc index 093f772..b5d9406 100644 --- a/storage/perfschema/pfs_server.cc +++ b/storage/perfschema/pfs_server.cc @@ -37,6 +37,7 @@ #include "pfs_account.h" #include "pfs_defaults.h" #include "pfs_digest.h" +#include "pfs_server.h" PFS_global_param pfs_param;