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PG-286: Reduce calls to pgstat_fetch_stat_numbackends(). 

After couple CPU profiling sessions with perf, it was detected that the
function pgstat_fetch_stat_numbackends() is very expensive, reading the
implementation on PostgreSQL's backend_status.c just confirmed that.

We use that function on pg_stat_monitor to retrieve the application name
and IP address of the client, we now cache the results in order to avoid
calling it for every query being processed.
pull/184/head
Diego Fronza 2021-12-03 14:14:31 -03:00 committed by Hamid Akhtar
parent 8c61e24f95
commit b798ffd461
1 changed files with 41 additions and 34 deletions
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75
pg_stat_monitor.c
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@ -104,12 +104,11 @@ PG_FUNCTION_INFO_V1(pg_stat_monitor_settings);
PG_FUNCTION_INFO_V1(get_histogram_timings);
PG_FUNCTION_INFO_V1(pg_stat_monitor_hook_stats);
static uint pg_get_client_addr(void);
static int pg_get_application_name(char* application_name);
static uint pg_get_client_addr(bool *ok);
static int pg_get_application_name(char *application_name, bool *ok);
static PgBackendStatus *pg_get_backend_status(void);
static Datum intarray_get_datum(int32 arr[], int len);
#if PG_VERSION_NUM < 140000
DECLARE_HOOK(void pgss_post_parse_analyze, ParseState *pstate, Query *query);
#else
@ -1112,8 +1111,8 @@ static PgBackendStatus*
pg_get_backend_status(void)
{
LocalPgBackendStatus *local_beentry;
int num_backends = pgstat_fetch_stat_numbackends();
int i;
int num_backends = pgstat_fetch_stat_numbackends();
int i;
for (i = 1; i <= num_backends; i++)
{
@ -1132,46 +1131,44 @@ pg_get_backend_status(void)
}
static int
pg_get_application_name(char *application_name)
pg_get_application_name(char *application_name, bool *ok)
{
PgBackendStatus *beentry = pg_get_backend_status();
if (!beentry)
return snprintf(application_name, APPLICATIONNAME_LEN, "%s", "postmaster");
return snprintf(application_name, APPLICATIONNAME_LEN, "%s", beentry->st_appname);
if (!beentry)
return snprintf(application_name, APPLICATIONNAME_LEN, "%s", "unknown");
*ok = true;
return snprintf(application_name, APPLICATIONNAME_LEN, "%s", beentry->st_appname);
}
static uint
pg_get_client_addr(void)
pg_get_client_addr(bool *ok)
{
PgBackendStatus *beentry = pg_get_backend_status();
char remote_host[NI_MAXHOST];
int ret;
static uint localhost = 0;
char remote_host[NI_MAXHOST];
int ret;
remote_host[0] = '\0';
if (!beentry)
return ntohl(inet_addr("127.0.0.1"));
*ok = true;
ret = pg_getnameinfo_all(&beentry->st_clientaddr.addr,
beentry->st_clientaddr.salen,
remote_host, sizeof(remote_host),
NULL, 0,
NI_NUMERICHOST | NI_NUMERICSERV);
if (ret != 0)
{
if (localhost == 0)
localhost = ntohl(inet_addr("127.0.0.1"));
return localhost;
}
return ntohl(inet_addr("127.0.0.1"));
if (strcmp(remote_host, "[local]") == 0)
{
if (localhost == 0)
localhost = ntohl(inet_addr("127.0.0.1"));
return localhost;
}
return ntohl(inet_addr("127.0.0.1"));
return ntohl(inet_addr(remote_host));
}
@ -1191,11 +1188,11 @@ pgss_update_entry(pgssEntry *entry,
BufferUsage *bufusage,
WalUsage *walusage,
bool reset,
pgssStoreKind kind)
pgssStoreKind kind,
const char *app_name,
size_t app_name_len)
{
int index;
char application_name[APPLICATIONNAME_LEN];
int application_name_len = pg_get_application_name(application_name);
double old_mean;
int message_len = error_info ? strlen (error_info->message) : 0;
int comments_len = comments ? strlen (comments) : 0;
@ -1264,11 +1261,11 @@ pgss_update_entry(pgssEntry *entry,
e->counters.resp_calls[index]++;
}
if (plan_text_len > 0)
if (plan_text_len > 0 && !e->counters.planinfo.plan_text[0])
_snprintf(e->counters.planinfo.plan_text, plan_info->plan_text, plan_text_len + 1, PLAN_TEXT_LEN);
if (application_name_len > 0)
_snprintf(e->counters.info.application_name, application_name, application_name_len + 1, APPLICATIONNAME_LEN);
if (app_name_len > 0 && !e->counters.info.application_name[0])
_snprintf(e->counters.info.application_name, app_name, app_name_len + 1, APPLICATIONNAME_LEN);
e->counters.info.num_relations = num_relations;
_snprintf2(e->counters.info.relations, relations, num_relations, REL_LEN);
@ -1465,8 +1462,8 @@ pgss_store(uint64 queryid,
pgssHashKey key;
pgssEntry *entry;
pgssSharedState *pgss = pgsm_get_ss();
char application_name[APPLICATIONNAME_LEN];
int application_name_len;
static char application_name[APPLICATIONNAME_LEN] = "";
static int application_name_len = 0;
bool reset = false;
uint64 bucketid;
uint64 prev_bucket_id;
@ -1474,6 +1471,9 @@ pgss_store(uint64 queryid,
uint64 planid;
uint64 appid;
char comments[512] = "";
static bool found_app_name = false;
static bool found_client_addr = false;
static uint client_addr = 0;
/* Monitoring is disabled */
if (!PGSM_ENABLED)
@ -1492,8 +1492,13 @@ pgss_store(uint64 queryid,
else
userid = GetUserId();
application_name_len = pg_get_application_name(application_name);
planid = plan_info ? plan_info->planid: 0;
if (!found_app_name)
application_name_len = pg_get_application_name(application_name, &found_app_name);
if (!found_client_addr)
client_addr = pg_get_client_addr(&found_client_addr);
planid = plan_info ? plan_info->planid : 0;
appid = djb2_hash((unsigned char *)application_name, application_name_len);
extract_query_comments(query, comments, sizeof(comments));
@ -1508,7 +1513,7 @@ pgss_store(uint64 queryid,
key.userid = userid;
key.dbid = MyDatabaseId;
key.queryid = queryid;
key.ip = pg_get_client_addr();
key.ip = client_addr;
key.planid = planid;
key.appid = appid;
#if PG_VERSION_NUM < 140000
@ -1597,7 +1602,9 @@ pgss_store(uint64 queryid,
bufusage, /* bufusage */
walusage, /* walusage */
reset, /* reset */
kind); /* kind */
kind, /* kind */
application_name,
application_name_len);
LWLockRelease(pgss->lock);
}