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PG-624: pg_stat_monitor: Possible server crash when running pgbench with pg_stat_monitor loaded (#396) 

PG-624: pg_stat_monitor: Possible server crash when running pgbench
with pg_stat_monitor loaded

It appears that this issue was being caused by improper handling of
dynamic number of buckets. This commit resolves the issue.

Also, as part of a larger cleanup, memory context has been moved to
local space from shared storage. Also, some unwanted
and no-longer-needed variables are removed.

Co-authored-by: Muhammad Usama <muhammad.usama@percona.com>
pull/399/head
Hamid Akhtar 2023-05-12 21:51:55 +05:00 committed by Muhammad Usama
parent 2ceb47e3cd
commit 39d9419bd0
3 changed files with 22 additions and 21 deletions
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21
hash_query.c
View File

@ -23,6 +23,9 @@ static PGSM_HASH_TABLE_HANDLE pgsm_create_bucket_hash(pgsmSharedState * pgsm, ds
static Size pgsm_get_shared_area_size(void);
static void InitializeSharedState(pgsmSharedState * pgsm);
#define PGSM_BUCKET_INFO_SIZE (sizeof(TimestampTz) * pgsm_max_buckets)
#define PGSM_SHARED_STATE_SIZE (sizeof(pgsmSharedState) + PGSM_BUCKET_INFO_SIZE)
#if USE_DYNAMIC_HASH
/* parameter for the shared hash */
static dshash_parameters dsh_params = {
@ -56,7 +59,7 @@ pgsm_query_area_size(void)
Size
pgsm_ShmemSize(void)
{
Size sz = MAXALIGN(sizeof(pgsmSharedState));
Size sz = MAXALIGN(PGSM_SHARED_STATE_SIZE);
sz = add_size(sz, MAX_QUERY_BUF);
#if USE_DYNAMIC_HASH
@ -114,7 +117,7 @@ pgsm_startup(void)
SpinLockInit(&pgsm->mutex);
InitializeSharedState(pgsm);
/* the allocation of pgsmSharedState itself */
p += MAXALIGN(sizeof(pgsmSharedState));
p += MAXALIGN(PGSM_SHARED_STATE_SIZE);
pgsm->raw_dsa_area = p;
dsa = dsa_create_in_place(pgsm->raw_dsa_area,
pgsm_query_area_size(),
@ -138,6 +141,10 @@ pgsm_startup(void)
* references.
*/
dsa_detach(dsa);
pgsmStateLocal.pgsm_mem_cxt = AllocSetContextCreate(TopMemoryContext,
"pg_stat_monitor local store",
ALLOCSET_DEFAULT_SIZES);
}
#ifdef BENCHMARK
@ -158,10 +165,6 @@ InitializeSharedState(pgsmSharedState * pgsm)
{
pg_atomic_init_u64(&pgsm->current_wbucket, 0);
pg_atomic_init_u64(&pgsm->prev_bucket_sec, 0);
memset(&pgsm->bucket_entry, 0, MAX_BUCKETS * sizeof(uint64));
pgsm->pgsm_mem_cxt = AllocSetContextCreate(TopMemoryContext,
"pg_stat_monitor local store",
ALLOCSET_DEFAULT_SIZES);
}
@ -235,6 +238,11 @@ pgsm_attach_shmem(void)
MemoryContextSwitchTo(oldcontext);
}
MemoryContext GetPgsmMemoryContext(void)
{
return pgsmStateLocal.pgsm_mem_cxt;
}
dsa_area *
get_dsa_area_for_query_text(void)
{
@ -290,7 +298,6 @@ hash_entry_alloc(pgsmSharedState * pgsm, pgsmHashKey * key, int encoding)
elog(DEBUG1, "[pg_stat_monitor] hash_entry_alloc: OUT OF MEMORY.");
else if (!found)
{
pgsm->bucket_entry[pg_atomic_read_u64(&pgsm->current_wbucket)]++;
/* New entry, initialize it */
/* reset the statistics */
memset(&entry->counters, 0, sizeof(Counters));

7
pg_stat_monitor.c
View File

@ -1590,7 +1590,7 @@ static void
pgsm_add_to_list(pgsmEntry * entry, char *query_text, int query_len)
{
/* Switch to pgsm memory context */
MemoryContext oldctx = MemoryContextSwitchTo(pgsm_get_ss()->pgsm_mem_cxt);
MemoryContext oldctx = MemoryContextSwitchTo(GetPgsmMemoryContext());
entry->query_text.query_pointer = pnstrdup(query_text, query_len);
lentries = lappend(lentries, entry);
@ -1645,7 +1645,8 @@ static void
pgsm_cleanup_callback(void *arg)
{
/* Reset the memory context holding the list */
MemoryContextReset(pgsm_get_ss()->pgsm_mem_cxt);
MemoryContextReset(GetPgsmMemoryContext());
lentries = NIL;
callback_setup = false;
}
@ -1666,7 +1667,7 @@ pgsm_create_hash_entry(uint64 bucket_id, uint64 queryid, PlanInfo * plan_info)
char *username = NULL;
/* Create an entry in the pgsm memory context */
oldctx = MemoryContextSwitchTo(pgsm_get_ss()->pgsm_mem_cxt);
oldctx = MemoryContextSwitchTo(GetPgsmMemoryContext());
entry = palloc0(sizeof(pgsmEntry));
/*

15
pg_stat_monitor.h
View File

@ -77,7 +77,6 @@
#define HISTOGRAM_MAX_TIME 50000000
#define MAX_RESPONSE_BUCKET 50
#define INVALID_BUCKET_ID -1
#define MAX_BUCKETS 10
#define TEXT_LEN 255
#define ERROR_MESSAGE_LEN 100
#define REL_TYPENAME_LEN 64
@ -388,8 +387,6 @@ typedef struct pgsmSharedState
slock_t mutex; /* protects following fields only: */
pg_atomic_uint64 current_wbucket;
pg_atomic_uint64 prev_bucket_sec;
uint64 bucket_entry[MAX_BUCKETS];
TimestampTz bucket_start_time[MAX_BUCKETS]; /* start time of the bucket */
int hash_tranche_id;
void *raw_dsa_area; /* DSA area pointer to store query texts.
* dshash also lives in this memory when
@ -400,16 +397,9 @@ typedef struct pgsmSharedState
* hash table handle. can be either classic shared memory hash or dshash
* (if we are using USE_DYNAMIC_HASH)
*/
MemoryContext pgsm_mem_cxt;
/*
* context to store stats in local memory until they are pushed to shared
* hash
*/
int resp_calls[MAX_RESPONSE_BUCKET + 2]; /* execution time's in
* msec; including 2
* outlier buckets */
bool pgsm_oom;
TimestampTz bucket_start_time[]; /* start time of the bucket */
} pgsmSharedState;
typedef struct pgsmLocalState
@ -418,6 +408,8 @@ typedef struct pgsmLocalState
dsa_area *dsa; /* local dsa area for backend attached to the
* dsa area created by postmaster at startup. */
PGSM_HASH_TABLE *shared_hash;
MemoryContext pgsm_mem_cxt;
} pgsmLocalState;
#if PG_VERSION_NUM < 140000
@ -479,6 +471,7 @@ void pgsm_startup(void);
/* hash_query.c */
void pgsm_startup(void);
MemoryContext GetPgsmMemoryContext(void);
/* guc.c */
void init_guc(void);