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tc_active_instances: my_atomic to std::atomic

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This commit is contained in:
Sergey Vojtovich
2020-03-21 18:36:31 +04:00
parent 3b3f931570
commit 62687801ff
3 changed files with 24 additions and 15 deletions
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2
sql/mysqld.cc
View File

@ -7831,7 +7831,7 @@ SHOW_VAR status_vars[]= {
{"Subquery_cache_miss", (char*) &subquery_cache_miss, SHOW_LONG}, {"Subquery_cache_miss", (char*) &subquery_cache_miss, SHOW_LONG},
{"Table_locks_immediate", (char*) &locks_immediate, SHOW_LONG}, {"Table_locks_immediate", (char*) &locks_immediate, SHOW_LONG},
{"Table_locks_waited", (char*) &locks_waited, SHOW_LONG}, {"Table_locks_waited", (char*) &locks_waited, SHOW_LONG},
{"Table_open_cache_active_instances", (char*) &tc_active_instances, SHOW_UINT}, {"Table_open_cache_active_instances", (char*) &show_tc_active_instances, SHOW_SIMPLE_FUNC},
{"Table_open_cache_hits", (char*) offsetof(STATUS_VAR, table_open_cache_hits), SHOW_LONGLONG_STATUS}, {"Table_open_cache_hits", (char*) offsetof(STATUS_VAR, table_open_cache_hits), SHOW_LONGLONG_STATUS},
{"Table_open_cache_misses", (char*) offsetof(STATUS_VAR, table_open_cache_misses), SHOW_LONGLONG_STATUS}, {"Table_open_cache_misses", (char*) offsetof(STATUS_VAR, table_open_cache_misses), SHOW_LONGLONG_STATUS},
{"Table_open_cache_overflows", (char*) offsetof(STATUS_VAR, table_open_cache_overflows), SHOW_LONGLONG_STATUS}, {"Table_open_cache_overflows", (char*) offsetof(STATUS_VAR, table_open_cache_overflows), SHOW_LONGLONG_STATUS},

34
sql/table_cache.cc
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@ -56,7 +56,7 @@
ulong tdc_size; /**< Table definition cache threshold for LRU eviction. */ ulong tdc_size; /**< Table definition cache threshold for LRU eviction. */
ulong tc_size; /**< Table cache threshold for LRU eviction. */ ulong tc_size; /**< Table cache threshold for LRU eviction. */
uint32 tc_instances; uint32 tc_instances;
uint32 tc_active_instances= 1; static std::atomic<uint32_t> tc_active_instances(1);
static std::atomic<bool> tc_contention_warning_reported; static std::atomic<bool> tc_contention_warning_reported;
/** Data collections. */ /** Data collections. */
@ -163,7 +163,7 @@ struct Table_cache_instance
overhead on TABLE object release. All other table cache mutex acquistions overhead on TABLE object release. All other table cache mutex acquistions
are considered out of hot path and are not instrumented either. are considered out of hot path and are not instrumented either.
*/ */
void lock_and_check_contention(uint32 n_instances, uint32 instance) void lock_and_check_contention(uint32_t n_instances, uint32_t instance)
{ {
if (mysql_mutex_trylock(&LOCK_table_cache)) if (mysql_mutex_trylock(&LOCK_table_cache))
{ {
@ -172,11 +172,10 @@ struct Table_cache_instance
{ {
if (n_instances < tc_instances) if (n_instances < tc_instances)
{ {
if (my_atomic_cas32_weak_explicit((int32*) &tc_active_instances, if (tc_active_instances.
(int32*) &n_instances, compare_exchange_weak(n_instances, n_instances + 1,
(int32) n_instances + 1, std::memory_order_relaxed,
MY_MEMORY_ORDER_RELAXED, std::memory_order_relaxed))
MY_MEMORY_ORDER_RELAXED))
{ {
sql_print_information("Detected table cache mutex contention at instance %d: " sql_print_information("Detected table cache mutex contention at instance %d: "
"%d%% waits. Additional table cache instance " "%d%% waits. Additional table cache instance "
@ -354,8 +353,8 @@ void tc_purge(bool mark_flushed)
void tc_add_table(THD *thd, TABLE *table) void tc_add_table(THD *thd, TABLE *table)
{ {
uint32 i= thd->thread_id % my_atomic_load32_explicit((int32*) &tc_active_instances, uint32_t i=
MY_MEMORY_ORDER_RELAXED); thd->thread_id % tc_active_instances.load(std::memory_order_relaxed);
TABLE *LRU_table= 0; TABLE *LRU_table= 0;
TDC_element *element= table->s->tdc; TDC_element *element= table->s->tdc;
@ -408,10 +407,8 @@ void tc_add_table(THD *thd, TABLE *table)
TABLE *tc_acquire_table(THD *thd, TDC_element *element) TABLE *tc_acquire_table(THD *thd, TDC_element *element)
{ {
uint32 n_instances= uint32_t n_instances= tc_active_instances.load(std::memory_order_relaxed);
my_atomic_load32_explicit((int32*) &tc_active_instances, uint32_t i= thd->thread_id % n_instances;
MY_MEMORY_ORDER_RELAXED);
uint32 i= thd->thread_id % n_instances;
TABLE *table; TABLE *table;
tc[i].lock_and_check_contention(n_instances, i); tc[i].lock_and_check_contention(n_instances, i);
@ -1342,3 +1339,14 @@ int tdc_iterate(THD *thd, my_hash_walk_action action, void *argument,
} }
return res; return res;
} }
int show_tc_active_instances(THD *thd, SHOW_VAR *var, char *buff,
enum enum_var_type scope)
{
var->type= SHOW_UINT;
var->value= buff;
*(reinterpret_cast<uint32_t*>(buff))=
tc_active_instances.load(std::memory_order_relaxed);
return 0;
}

3
sql/table_cache.h
View File

@ -71,7 +71,6 @@ enum enum_tdc_remove_table_type
extern ulong tdc_size; extern ulong tdc_size;
extern ulong tc_size; extern ulong tc_size;
extern uint32 tc_instances; extern uint32 tc_instances;
extern uint32 tc_active_instances;
extern bool tdc_init(void); extern bool tdc_init(void);
extern void tdc_start_shutdown(void); extern void tdc_start_shutdown(void);
@ -98,6 +97,8 @@ extern int tdc_iterate(THD *thd, my_hash_walk_action action, void *argument,
bool no_dups= false); bool no_dups= false);
extern uint tc_records(void); extern uint tc_records(void);
int show_tc_active_instances(THD *thd, SHOW_VAR *var, char *buff,
enum enum_var_type scope);
extern void tc_purge(bool mark_flushed= false); extern void tc_purge(bool mark_flushed= false);
extern void tc_add_table(THD *thd, TABLE *table); extern void tc_add_table(THD *thd, TABLE *table);
extern void tc_release_table(TABLE *table); extern void tc_release_table(TABLE *table);