From df0580b7413836285e001e8ef9c45855a503118e Mon Sep 17 00:00:00 2001 From: Muhammad Usama Date: Tue, 20 Dec 2022 17:29:15 +0500 Subject: [PATCH] PG-488: pg_stat_monitor: Overflow management. Reimplement the storage mechanism of buckets and query texts using Dynamic shared memory. Since the dynamic shared memory can grow into a swap area, so we get the overflow out of the box. oreover the new design saves the query pointer inside the bucket and eventually, the query text gets evicted with the bucket recycle. Finally, the dynamic shared memory hash has a built-in locking mechanism so we can revisit the whole locking in pg_stat_monitor has potential for lots of performance improvements --- hash_query.c | 225 ++++++++++++++------- pg_stat_monitor.c | 490 ++++++++-------------------------------------- pg_stat_monitor.h | 44 ++--- 3 files changed, 246 insertions(+), 513 deletions(-) diff --git a/hash_query.c b/hash_query.c index 3139716..48e9532 100644 --- a/hash_query.c +++ b/hash_query.c @@ -16,59 +16,93 @@ */ #include "postgres.h" #include "nodes/pg_list.h" - #include "pg_stat_monitor.h" +static pgsmLocalState pgsmStateLocal; -static pgssSharedState *pgss; -static HTAB *pgss_hash; -static HTAB *pgss_query_hash; +/* parameter for the shared hash */ + static dshash_parameters dsh_params = { + sizeof(pgssHashKey), + sizeof(pgssEntry), + dshash_memcmp, + dshash_memhash + }; +static void pgsm_proc_exit(int code, Datum arg); - -static HTAB * -hash_init(const char *hash_name, int key_size, int entry_size, int hash_size) +static Size +pgsm_query_area_size(void) { - HASHCTL info; - - memset(&info, 0, sizeof(info)); - info.keysize = key_size; - info.entrysize = entry_size; - return ShmemInitHash(hash_name, hash_size, hash_size, &info, HASH_ELEM | HASH_BLOBS); + Size sz = MAXALIGN(MAX_QUERY_BUF); + return MAXALIGN(sz); } +Size +pgsm_ShmemSize(void) + { + Size sz = MAXALIGN(sizeof(pgssSharedState)); + sz = add_size(sz, pgsm_query_area_size()); + sz = add_size(sz, hash_estimate_size(MAX_BUCKET_ENTRIES, sizeof(pgssEntry))); + return sz; + } + void pgss_startup(void) { bool found = false; - + pgssSharedState *pgss; /* reset in case this is a restart within the postmaster */ - - pgss = NULL; - pgss_hash = NULL; + pgsmStateLocal.dsa = NULL; + pgsmStateLocal.shared_hash = NULL; + pgsmStateLocal.shared_pgssState = NULL; /* * Create or attach to the shared memory state, including hash table */ LWLockAcquire(AddinShmemInitLock, LW_EXCLUSIVE); - pgss = ShmemInitStruct("pg_stat_monitor", sizeof(pgssSharedState), &found); + pgss = ShmemInitStruct("pg_stat_monitor", pgsm_ShmemSize(), &found); if (!found) { /* First time through ... */ + dsa_area *dsa; + dshash_table *dsh; + char *p = (char *) pgss; + pgss->lock = &(GetNamedLWLockTranche("pg_stat_monitor"))->lock; SpinLockInit(&pgss->mutex); ResetSharedState(pgss); + /* the allocation of pgssSharedState itself */ + p += MAXALIGN(sizeof(pgssSharedState)); + pgss->raw_dsa_area = p; + dsa = dsa_create_in_place(pgss->raw_dsa_area, + pgsm_query_area_size(), + LWLockNewTrancheId(), 0); + dsa_pin(dsa); + dsa_set_size_limit(dsa, pgsm_query_area_size()); + + pgss->hash_tranche_id = LWLockNewTrancheId(); + + dsh_params.tranche_id = pgss->hash_tranche_id; + dsh = dshash_create(dsa, &dsh_params, 0); + + pgss->hash_handle = dshash_get_hash_table_handle(dsh); + + if (PGSM_OVERFLOW_TARGET == OVERFLOW_TARGET_DISK) + dsa_set_size_limit(dsa, -1); + + pgsmStateLocal.shared_pgssState = pgss; + /* + * Postmaster will never access these again, thus free the local + * dsa/dshash references. + */ + dshash_detach(dsh); + dsa_detach(dsa); } #ifdef BENCHMARK init_hook_stats(); #endif - set_qbuf((unsigned char *) ShmemAlloc(MAX_QUERY_BUF)); - - pgss_hash = hash_init("pg_stat_monitor: bucket hashtable", sizeof(pgssHashKey), sizeof(pgssEntry), MAX_BUCKET_ENTRIES); - pgss_query_hash = hash_init("pg_stat_monitor: queryID hashtable", sizeof(uint64), sizeof(pgssQueryEntry), MAX_BUCKET_ENTRIES); - LWLockRelease(AddinShmemInitLock); /* @@ -78,23 +112,49 @@ pgss_startup(void) on_shmem_exit(pgss_shmem_shutdown, (Datum) 0); } +void +pgsm_attach_shmem(void) +{ + MemoryContext oldcontext; + if (pgsmStateLocal.dsa) + return; + + oldcontext = MemoryContextSwitchTo(TopMemoryContext); + + pgsmStateLocal.dsa = dsa_attach_in_place(pgsmStateLocal.shared_pgssState->raw_dsa_area, + NULL); + dsa_pin_mapping(pgsmStateLocal.dsa); + + dsh_params.tranche_id = pgsmStateLocal.shared_pgssState->hash_tranche_id; + pgsmStateLocal.shared_hash = dshash_attach(pgsmStateLocal.dsa, &dsh_params, + pgsmStateLocal.shared_pgssState->hash_handle, 0); + + on_proc_exit(pgsm_proc_exit, 0); + + MemoryContextSwitchTo(oldcontext); +} + +dsa_area* +get_dsa_area_for_query_text(void) +{ + pgsm_attach_shmem(); + return pgsmStateLocal.dsa; +} + +dshash_table* +get_pgssHash(void) +{ + pgsm_attach_shmem(); + return pgsmStateLocal.shared_hash; +} + pgssSharedState * pgsm_get_ss(void) { - return pgss; + pgsm_attach_shmem(); + return pgsmStateLocal.shared_pgssState; } -HTAB * -pgsm_get_hash(void) -{ - return pgss_hash; -} - -HTAB * -pgsm_get_query_hash(void) -{ - return pgss_query_hash; -} /* * shmem_shutdown hook: Dump statistics into file. @@ -106,26 +166,24 @@ void pgss_shmem_shutdown(int code, Datum arg) { /* Don't try to dump during a crash. */ + elog(LOG,"pgss_shmem_shutdown"); if (code) return; - pgss = NULL; + pgsmStateLocal.shared_pgssState = NULL; /* Safety check ... shouldn't get here unless shmem is set up. */ if (!IsHashInitialize()) return; } -Size -hash_memsize(void) +static void +pgsm_proc_exit(int code, Datum arg) { - Size size; - - size = MAXALIGN(sizeof(pgssSharedState)); - size += MAXALIGN(MAX_QUERY_BUF); - size = add_size(size, hash_estimate_size(MAX_BUCKET_ENTRIES, sizeof(pgssEntry))); - size = add_size(size, hash_estimate_size(MAX_BUCKET_ENTRIES, sizeof(pgssQueryEntry))); - - return size; + Assert(pgsmStateLocal.dsa); + dshash_detach(pgsmStateLocal.shared_hash); + pgsmStateLocal.shared_hash = NULL; + dsa_detach(pgsmStateLocal.dsa); + pgsmStateLocal.dsa = NULL; } pgssEntry * @@ -134,13 +192,9 @@ hash_entry_alloc(pgssSharedState *pgss, pgssHashKey *key, int encoding) pgssEntry *entry = NULL; bool found = false; - if (hash_get_num_entries(pgss_hash) >= MAX_BUCKET_ENTRIES) - { - elog(DEBUG1, "pg_stat_monitor: out of memory"); - return NULL; - } /* Find or create an entry with desired hash code */ - entry = (pgssEntry *) hash_search(pgss_hash, key, HASH_ENTER_NULL, &found); + entry = (pgssEntry *) dshash_find_or_insert(pgsmStateLocal.shared_hash, key, &found); + // entry = (pgssEntry *) hash_search(pgss_hash, key, HASH_ENTER_NULL, &found); if (entry == NULL) elog(DEBUG1, "hash_entry_alloc: OUT OF MEMORY"); else if (!found) @@ -155,6 +209,7 @@ hash_entry_alloc(pgssSharedState *pgss, pgssHashKey *key, int encoding) /* ... and don't forget the query text metadata */ entry->encoding = encoding; } + dshash_release_lock(pgsmStateLocal.shared_hash, entry); return entry; } @@ -174,17 +229,22 @@ hash_entry_alloc(pgssSharedState *pgss, pgssHashKey *key, int encoding) void hash_entry_dealloc(int new_bucket_id, int old_bucket_id, unsigned char *query_buffer) { - HASH_SEQ_STATUS hash_seq; + dshash_seq_status hstat; pgssEntry *entry = NULL; - /* Store pending query ids from the previous bucket. */ List *pending_entries = NIL; ListCell *pending_entry; + if (!pgsmStateLocal.shared_hash) + return; + /* Iterate over the hash table. */ - hash_seq_init(&hash_seq, pgss_hash); - while ((entry = hash_seq_search(&hash_seq)) != NULL) + dshash_seq_init(&hstat, pgsmStateLocal.shared_hash, true); + + while ((entry = dshash_seq_next(&hstat)) != NULL) { + dsa_pointer pdsa; + /* * Remove all entries if new_bucket_id == -1. Otherwise remove entry * in new_bucket_id if it has finished already. @@ -193,16 +253,14 @@ hash_entry_dealloc(int new_bucket_id, int old_bucket_id, unsigned char *query_bu (entry->key.bucket_id == new_bucket_id && (entry->counters.state == PGSS_FINISHED || entry->counters.state == PGSS_ERROR))) { - if (new_bucket_id == -1) - { - /* - * pg_stat_monitor_reset(), remove entry from query hash table - * too. - */ - hash_search(pgss_query_hash, &(entry->key.queryid), HASH_REMOVE, NULL); - } + pdsa = entry->query_pos; + dsa_pointer parent_qdsa = entry->counters.info.parent_query; + dshash_delete_current(&hstat); + dsa_free(pgsmStateLocal.dsa, pdsa); + + if (DsaPointerIsValid(parent_qdsa)) + dsa_free(pgsmStateLocal.dsa, parent_qdsa); - entry = hash_search(pgss_hash, &entry->key, HASH_REMOVE, NULL); } /* @@ -238,7 +296,11 @@ hash_entry_dealloc(int new_bucket_id, int old_bucket_id, unsigned char *query_bu if (entry->counters.calls.calls > 1) entry->counters.state = PGSS_FINISHED; else - entry = hash_search(pgss_hash, &entry->key, HASH_REMOVE, NULL); + { + pdsa = entry->query_pos; + dshash_delete_current(&hstat); + dsa_free(pgsmStateLocal.dsa, pdsa); + } continue; } @@ -266,11 +328,15 @@ hash_entry_dealloc(int new_bucket_id, int old_bucket_id, unsigned char *query_bu if (entry->counters.calls.calls > 1) entry->counters.state = PGSS_FINISHED; else - entry = hash_search(pgss_hash, &entry->key, HASH_REMOVE, NULL); + { + pdsa = entry->query_pos; + dshash_delete_current(&hstat); + dsa_free(pgsmStateLocal.dsa, pdsa); + } } } } - + dshash_seq_term(&hstat); /* * Iterate over the list of pending queries in order to add them back to * the hash table with the updated bucket id. @@ -281,7 +347,8 @@ hash_entry_dealloc(int new_bucket_id, int old_bucket_id, unsigned char *query_bu pgssEntry *new_entry; pgssEntry *old_entry = (pgssEntry *) lfirst(pending_entry); - new_entry = (pgssEntry *) hash_search(pgss_hash, &old_entry->key, HASH_ENTER_NULL, &found); + + new_entry = (pgssEntry *) dshash_find_or_insert(pgsmStateLocal.shared_hash, &old_entry->key, &found); if (new_entry == NULL) elog(DEBUG1, "%s", "pg_stat_monitor: out of memory"); else if (!found) @@ -292,8 +359,9 @@ hash_entry_dealloc(int new_bucket_id, int old_bucket_id, unsigned char *query_bu new_entry->encoding = old_entry->encoding; new_entry->query_pos = old_entry->query_pos; } - free(old_entry); + dshash_release_lock(pgsmStateLocal.shared_hash, entry); + } list_free(pending_entries); @@ -306,16 +374,22 @@ void hash_entry_reset() { pgssSharedState *pgss = pgsm_get_ss(); - HASH_SEQ_STATUS hash_seq; + dshash_seq_status hstat; pgssEntry *entry; LWLockAcquire(pgss->lock, LW_EXCLUSIVE); - hash_seq_init(&hash_seq, pgss_hash); - while ((entry = hash_seq_search(&hash_seq)) != NULL) + dshash_seq_init(&hstat, pgsmStateLocal.shared_hash, true); + + while ((entry = dshash_seq_next(&hstat)) != NULL) { - hash_search(pgss_hash, &entry->key, HASH_REMOVE, NULL); + dsa_pointer pdsa = entry->query_pos; + dshash_delete_current(&hstat); + dsa_free(pgsmStateLocal.dsa, pdsa); } + + dshash_seq_term(&hstat); + pg_atomic_write_u64(&pgss->current_wbucket, 0); LWLockRelease(pgss->lock); } @@ -323,6 +397,5 @@ hash_entry_reset() bool IsHashInitialize(void) { - return (pgss != NULL && - pgss_hash != NULL); + return (pgsmStateLocal.shared_pgssState != NULL); } diff --git a/pg_stat_monitor.c b/pg_stat_monitor.c index ddf1765..bfb9619 100644 --- a/pg_stat_monitor.c +++ b/pg_stat_monitor.c @@ -32,7 +32,6 @@ PGSM_V2_0 } pgsmVersion; - PG_MODULE_MAGIC; #define BUILD_VERSION "2.0.0-dev" @@ -78,6 +77,7 @@ static int plan_nested_level = 0; /* The array to store outer layer query id*/ uint64 *nested_queryids; +char **nested_query_txts; /* Regex object used to extract query comments. */ static regex_t preg_query_comments; @@ -88,13 +88,11 @@ static struct rusage rusage_start; static struct rusage rusage_end; /* Query buffer, store queries' text. */ -static unsigned char *pgss_qbuf = NULL; static char *pgss_explain(QueryDesc *queryDesc); static void extract_query_comments(const char *query, char *comments, size_t max_len); static int get_histogram_bucket(double q_time); static bool IsSystemInitialized(void); -static bool dump_queries_buffer(int bucket_id, unsigned char *buf, int buf_len); static double time_diff(struct timeval end, struct timeval start); static void request_additional_shared_resources(void); @@ -230,7 +228,6 @@ static uint64 djb2_hash(unsigned char *str, size_t len); /* Same as above, but stores the calculated string length into *out_len (small optimization) */ static uint64 djb2_hash_str(unsigned char *str, int *out_len); - /* * Module load callback */ @@ -239,7 +236,6 @@ void _PG_init(void) { int rc; - char file_name[1024]; elog(DEBUG2, "pg_stat_monitor: %s()", __FUNCTION__); @@ -266,8 +262,6 @@ _PG_init(void) EnableQueryId(); #endif - snprintf(file_name, 1024, "%s", PGSM_TEXT_FILE); - unlink(file_name); EmitWarningsOnPlaceholders("pg_stat_monitor"); @@ -313,6 +307,7 @@ _PG_init(void) ExecutorCheckPerms_hook = HOOK(pgss_ExecutorCheckPerms); nested_queryids = (uint64 *) malloc(sizeof(uint64) * max_stack_depth); + nested_query_txts = (char **) malloc(sizeof(char*) * max_stack_depth); system_init = true; } @@ -335,6 +330,7 @@ _PG_fini(void) emit_log_hook = prev_emit_log_hook; free(nested_queryids); + free(nested_query_txts); regfree(&preg_query_comments); hash_entry_reset(); @@ -363,7 +359,7 @@ request_additional_shared_resources(void) * the postmaster process.) We'll allocate or attach to the shared * resources in pgss_shmem_startup(). */ - RequestAddinShmemSpace(hash_memsize() + HOOK_STATS_SIZE); + RequestAddinShmemSpace(pgsm_ShmemSize() + HOOK_STATS_SIZE); RequestNamedLWLockTranche("pg_stat_monitor", 1); } /* @@ -554,7 +550,11 @@ pgss_ExecutorRun(QueryDesc *queryDesc, ScanDirection direction, uint64 count, bool execute_once) { if (exec_nested_level >= 0 && exec_nested_level < max_stack_depth) + { nested_queryids[exec_nested_level] = queryDesc->plannedstmt->queryId; + nested_query_txts[exec_nested_level] = strdup(queryDesc->sourceText); + } + exec_nested_level++; PG_TRY(); { @@ -564,13 +564,23 @@ pgss_ExecutorRun(QueryDesc *queryDesc, ScanDirection direction, uint64 count, standard_ExecutorRun(queryDesc, direction, count, execute_once); exec_nested_level--; if (exec_nested_level >= 0 && exec_nested_level < max_stack_depth) + { nested_queryids[exec_nested_level] = UINT64CONST(0); + if(nested_query_txts[exec_nested_level]) + free(nested_query_txts[exec_nested_level]); + nested_query_txts[exec_nested_level] = NULL; + } } PG_CATCH(); { exec_nested_level--; if (exec_nested_level >= 0 && exec_nested_level < max_stack_depth) + { nested_queryids[exec_nested_level] = UINT64CONST(0); + if(nested_query_txts[exec_nested_level]) + free(nested_query_txts[exec_nested_level]); + nested_query_txts[exec_nested_level] = NULL; + } PG_RE_THROW(); } PG_END_TRY(); @@ -1260,11 +1270,29 @@ pgss_update_entry(pgssEntry *entry, if (exec_nested_level > 0) { if (exec_nested_level >= 0 && exec_nested_level < max_stack_depth) + { + int parent_query_len = nested_query_txts[exec_nested_level - 1]? + strlen(nested_query_txts[exec_nested_level - 1]): 0; e->counters.info.parentid = nested_queryids[exec_nested_level - 1]; + if (parent_query_len > 0) + { + char *qry_buff; + dsa_area *query_dsa_area = get_dsa_area_for_query_text(); + dsa_pointer qry = dsa_allocate(query_dsa_area, parent_query_len+1); + qry_buff = dsa_get_address(query_dsa_area, qry); + memcpy(qry_buff, nested_query_txts[exec_nested_level - 1], parent_query_len); + qry_buff[parent_query_len] = 0; + e->counters.info.parent_query = qry; + } + else + e->counters.info.parent_query = InvalidDsaPointer; + + } } else { e->counters.info.parentid = UINT64CONST(0); + e->counters.info.parent_query = InvalidDsaPointer; } if (error_info) @@ -1381,7 +1409,6 @@ pgss_store(uint64 queryid, JumbleState *jstate, pgssStoreKind kind) { - HTAB *pgss_hash; pgssHashKey key; pgssEntry *entry; pgssSharedState *pgss = pgsm_get_ss(); @@ -1486,19 +1513,15 @@ pgss_store(uint64 queryid, #else key.toplevel = ((exec_nested_level + plan_nested_level) == 0); #endif - pgss_hash = pgsm_get_hash(); LWLockAcquire(pgss->lock, LW_SHARED); - entry = (pgssEntry *) hash_search(pgss_hash, &key, HASH_FIND, NULL); + entry = (pgssEntry *) dshash_find(get_pgssHash(), &key, false); if (!entry) { - pgssQueryEntry *query_entry; - bool query_found = false; - uint64 prev_qbuf_len = 0; - HTAB *pgss_query_hash; + dsa_pointer dsa_query_pointer; + char* query_buff; - pgss_query_hash = pgsm_get_query_hash(); /* * Create a new, normalized query string if caller asked. We don't @@ -1509,74 +1532,41 @@ pgss_store(uint64 queryid, */ if (jstate && PGSM_NORMALIZED_QUERY) { - LWLockRelease(pgss->lock); norm_query = generate_normalized_query(jstate, query, query_location, &query_len, GetDatabaseEncoding()); - LWLockAcquire(pgss->lock, LW_SHARED); } - query_entry = hash_search(pgss_query_hash, &queryid, HASH_ENTER_NULL, &query_found); - if (query_entry == NULL) - { - LWLockRelease(pgss->lock); - if (norm_query) - pfree(norm_query); - elog(DEBUG1, "pgss_store: out of memory (pgss_query_hash)."); - return; - } - else if (!query_found) - { - /* New query, truncate length if necessary. */ - if (query_len > PGSM_QUERY_MAX_LEN) - query_len = PGSM_QUERY_MAX_LEN; - } + /* New query, truncate length if necessary. */ + if (query_len > PGSM_QUERY_MAX_LEN) + query_len = PGSM_QUERY_MAX_LEN; /* Need exclusive lock to make a new hashtable entry - promote */ LWLockRelease(pgss->lock); LWLockAcquire(pgss->lock, LW_EXCLUSIVE); - if (!query_found) - { - if (!SaveQueryText(bucketid, - queryid, - pgss_qbuf, - norm_query ? norm_query : query, - query_len, - &query_entry->query_pos)) - { - LWLockRelease(pgss->lock); - if (norm_query) - pfree(norm_query); - elog(DEBUG1, "pgss_store: insufficient shared space for query."); - return; - } - - /* - * Save current query buffer length, if we fail to add a new new - * entry to the hash table then we must restore the original - * length. - */ - memcpy(&prev_qbuf_len, pgss_qbuf, sizeof(prev_qbuf_len)); - } + /* Save the query text in raw dsa area */ + dsa_area* query_dsa_area = get_dsa_area_for_query_text(); + dsa_query_pointer = dsa_allocate(query_dsa_area, query_len+1); + query_buff = dsa_get_address(query_dsa_area, dsa_query_pointer); + memcpy(query_buff, norm_query ? norm_query : query, query_len); + query_buff[query_len] = 0; /* OK to create a new hashtable entry */ entry = hash_entry_alloc(pgss, &key, GetDatabaseEncoding()); if (entry == NULL) { - if (!query_found) - { - /* Restore previous query buffer length. */ - memcpy(pgss_qbuf, &prev_qbuf_len, sizeof(prev_qbuf_len)); - } LWLockRelease(pgss->lock); if (norm_query) pfree(norm_query); return; } - entry->query_pos = query_entry->query_pos; + entry->query_pos = dsa_query_pointer; } + else + dshash_release_lock(get_pgssHash(), entry); + if (jstate == NULL) pgss_update_entry(entry, /* entry */ @@ -1619,9 +1609,6 @@ pg_stat_monitor_reset(PG_FUNCTION_ARGS) LWLockAcquire(pgss->lock, LW_EXCLUSIVE); hash_entry_dealloc(-1, -1, NULL); - /* Reset query buffer. */ - *(uint64 *) pgss_qbuf = 0; - LWLockRelease(pgss->lock); PG_RETURN_VOID(); } @@ -1678,13 +1665,12 @@ pg_stat_monitor_internal(FunctionCallInfo fcinfo, Tuplestorestate *tupstore; MemoryContext per_query_ctx; MemoryContext oldcontext; - HASH_SEQ_STATUS hash_seq; + dshash_seq_status hstat; pgssEntry *entry; char parentid_txt[32]; pgssSharedState *pgss = pgsm_get_ss(); - HTAB *pgss_hash = pgsm_get_hash(); - char *query_txt = (char *) palloc0(PGSM_QUERY_MAX_LEN + 1); - char *parent_query_txt = (char *) palloc0(PGSM_QUERY_MAX_LEN + 1); + char *query_txt = NULL; + char *parent_query_txt = NULL; int expected_columns = (api_version >= PGSM_V2_0)?PG_STAT_MONITOR_COLS_V2_0:PG_STAT_MONITOR_COLS_V1_0; /* Safety check... */ @@ -1722,10 +1708,11 @@ pg_stat_monitor_internal(FunctionCallInfo fcinfo, MemoryContextSwitchTo(oldcontext); - LWLockAcquire(pgss->lock, LW_SHARED); + // LWLockAcquire(pgss->lock, LW_SHARED); - hash_seq_init(&hash_seq, pgss_hash); - while ((entry = hash_seq_search(&hash_seq)) != NULL) + dshash_seq_init(&hstat, get_pgssHash(), false); + + while ((entry = dshash_seq_next(&hstat)) != NULL) { Datum values[PG_STAT_MONITOR_COLS] = {0}; bool nulls[PG_STAT_MONITOR_COLS] = {0}; @@ -1740,6 +1727,8 @@ pg_stat_monitor_internal(FunctionCallInfo fcinfo, uint64 userid = entry->key.userid; int64 ip = entry->key.ip; uint64 planid = entry->key.planid; + dsa_area *query_dsa_area; + char *query_ptr; #if PG_VERSION_NUM < 140000 bool toplevel = 1; bool is_allowed_role = is_member_of_role(GetUserId(), DEFAULT_ROLE_READ_ALL_STATS); @@ -1747,15 +1736,10 @@ pg_stat_monitor_internal(FunctionCallInfo fcinfo, bool is_allowed_role = is_member_of_role(GetUserId(), ROLE_PG_READ_ALL_STATS); bool toplevel = entry->key.toplevel; #endif - - if (read_query(pgss_qbuf, queryid, query_txt, entry->query_pos) == 0) - { - int rc; - - rc = read_query_buffer(bucketid, queryid, query_txt, entry->query_pos); - if (rc != 1) - snprintf(query_txt, 32, "%s", ""); - } + /* Load the query text from dsa area */ + query_dsa_area = get_dsa_area_for_query_text(); + query_ptr = dsa_get_address(query_dsa_area, entry->query_pos); + query_txt = pstrdup(query_ptr); /* copy counters to a local variable to keep locking time short */ { @@ -1783,15 +1767,17 @@ pg_stat_monitor_internal(FunctionCallInfo fcinfo, if (tmp.state == PGSS_PARSE || tmp.state == PGSS_PLAN) continue; + /* read the parent query text if any */ if (tmp.info.parentid != UINT64CONST(0)) { - if (read_query(pgss_qbuf, tmp.info.parentid, parent_query_txt, 0) == 0) + if (DsaPointerIsValid(tmp.info.parent_query)) { - int rc = read_query_buffer(bucketid, tmp.info.parentid, parent_query_txt, 0); - - if (rc != 1) - snprintf(parent_query_txt, 32, "%s", ""); + query_dsa_area = get_dsa_area_for_query_text(); + query_ptr = dsa_get_address(query_dsa_area, tmp.info.parent_query); + parent_query_txt = pstrdup(query_ptr); } + else + parent_query_txt = pstrdup("parent query text not available"); } /* bucketid at column number 0 */ values[i++] = Int64GetDatumFast(bucketid); @@ -2071,10 +2057,12 @@ pg_stat_monitor_internal(FunctionCallInfo fcinfo, tuplestore_putvalues(tupstore, tupdesc, values, nulls); } /* clean up and return the tuplestore */ - LWLockRelease(pgss->lock); + dshash_seq_term(&hstat); - pfree(query_txt); - pfree(parent_query_txt); + if(query_txt) + pfree(query_txt); + if(parent_query_txt) + pfree(parent_query_txt); tuplestore_donestoring(tupstore); } @@ -2120,7 +2108,6 @@ get_next_wbucket(pgssSharedState *pgss) if (update_bucket) { - char file_name[1024]; new_bucket_id = (tv.tv_sec / PGSM_BUCKET_TIME) % PGSM_MAX_BUCKETS; @@ -2128,24 +2115,7 @@ get_next_wbucket(pgssSharedState *pgss) prev_bucket_id = pg_atomic_exchange_u64(&pgss->current_wbucket, new_bucket_id); LWLockAcquire(pgss->lock, LW_EXCLUSIVE); - hash_entry_dealloc(new_bucket_id, prev_bucket_id, pgss_qbuf); - - if (pgss->overflow) - { - pgss->n_bucket_cycles += 1; - if (pgss->n_bucket_cycles >= PGSM_MAX_BUCKETS) - { - /* - * A full rotation of PGSM_MAX_BUCKETS buckets happened since - * we detected a query buffer overflow. - * Reset overflow state and remove the dump file. - */ - pgss->overflow = false; - pgss->n_bucket_cycles = 0; - snprintf(file_name, 1024, "%s", PGSM_TEXT_FILE); - unlink(file_name); - } - } + hash_entry_dealloc(new_bucket_id, prev_bucket_id, NULL); LWLockRelease(pgss->lock); @@ -3144,165 +3114,6 @@ intarray_get_datum(int32 arr[], int len) } -uint64 -read_query(unsigned char *buf, uint64 queryid, char *query, size_t pos) -{ - bool found = false; - uint64 query_id = 0; - uint64 query_len = 0; - uint64 rlen = 0; - uint64 buf_len = 0; - - memcpy(&buf_len, buf, sizeof(uint64)); - if (buf_len <= 0) - goto exit; - - /* If a position hint is given, try to locate the query directly. */ - if (pos != 0 && (pos + sizeof(uint64) + sizeof(uint64)) < buf_len) - { - memcpy(&query_id, &buf[pos], sizeof(uint64)); - if (query_id != queryid) - return 0; - - pos += sizeof(uint64); - - memcpy(&query_len, &buf[pos], sizeof(uint64)); /* query len */ - pos += sizeof(uint64); - - if (pos + query_len > buf_len) /* avoid reading past buffer's length. */ - return 0; - - memcpy(query, &buf[pos], query_len); /* Actual query */ - query[query_len] = '\0'; - - return queryid; - } - - rlen = sizeof(uint64); /* Move forwad to skip length bytes */ - for (;;) - { - if (rlen >= buf_len) - goto exit; - - memcpy(&query_id, &buf[rlen], sizeof(uint64)); /* query id */ - if (query_id == queryid) - found = true; - - rlen += sizeof(uint64); - if (buf_len <= rlen) - continue; - - memcpy(&query_len, &buf[rlen], sizeof(uint64)); /* query len */ - rlen += sizeof(uint64); - if (buf_len < rlen + query_len) - goto exit; - if (found) - { - if (query != NULL) - { - memcpy(query, &buf[rlen], query_len); /* Actual query */ - query[query_len] = 0; - } - return query_id; - } - rlen += query_len; - } -exit: - if (PGSM_OVERFLOW_TARGET == OVERFLOW_TARGET_NONE) - { - sprintf(query, "%s", ""); - return -1; - } - return 0; -} - -bool -SaveQueryText(uint64 bucketid, - uint64 queryid, - unsigned char *buf, - const char *query, - uint64 query_len, - size_t *query_pos) -{ - uint64 buf_len = 0; - - memcpy(&buf_len, buf, sizeof(uint64)); - if (buf_len == 0) - buf_len += sizeof(uint64); - - if (QUERY_BUFFER_OVERFLOW(buf_len, query_len)) - { - switch (PGSM_OVERFLOW_TARGET) - { - case OVERFLOW_TARGET_NONE: - return false; - case OVERFLOW_TARGET_DISK: - { - bool dump_ok; - pgssSharedState *pgss = pgsm_get_ss(); - - if (pgss->overflow) - { - elog(DEBUG1, "query buffer overflowed twice"); - return false; - } - - /* - * If the query buffer is empty, there is nothing to dump, - * this also means that the current query length exceeds - * MAX_QUERY_BUF. - */ - if (buf_len <= sizeof(uint64)) - return false; - - dump_ok = dump_queries_buffer(bucketid, buf, MAX_QUERY_BUF); - buf_len = sizeof(uint64); - - if (dump_ok) - { - pgss->overflow = true; - pgss->n_bucket_cycles = 0; - } - - /* - * We must check for overflow again, as the query length - * may exceed the total size allocated to the buffer - * (MAX_QUERY_BUF). - */ - if (QUERY_BUFFER_OVERFLOW(buf_len, query_len)) - { - /* - * If we successfully dumped the query buffer to disk, - * then reset the buffer, otherwise we could end up - * dumping the same buffer again. - */ - if (dump_ok) - *(uint64 *) buf = 0; - - return false; - } - - } - break; - default: - Assert(false); - break; - } - } - - *query_pos = buf_len; - - memcpy(&buf[buf_len], &queryid, sizeof(uint64)); /* query id */ - buf_len += sizeof(uint64); - - memcpy(&buf[buf_len], &query_len, sizeof(uint64)); /* query length */ - buf_len += sizeof(uint64); - - memcpy(&buf[buf_len], query, query_len); /* query */ - buf_len += query_len; - memcpy(buf, &buf_len, sizeof(uint64)); - return true; -} Datum pg_stat_monitor_settings(PG_FUNCTION_ARGS) @@ -3440,12 +3251,6 @@ pg_stat_monitor_hook_stats(PG_FUNCTION_ARGS) return (Datum) 0; } -void -set_qbuf(unsigned char *buf) -{ - pgss_qbuf = buf; - *(uint64 *) pgss_qbuf = 0; -} void pgsm_emit_log_hook(ErrorData *edata) @@ -3482,145 +3287,6 @@ IsSystemInitialized(void) return (system_init && IsHashInitialize()); } -static bool -dump_queries_buffer(int bucket_id, unsigned char *buf, int buf_len) -{ - int fd = 0; - char file_name[1024]; - bool success = true; - int off = 0; - int tries = 0; - - snprintf(file_name, 1024, "%s", PGSM_TEXT_FILE); - fd = OpenTransientFile(file_name, O_RDWR | O_CREAT | O_APPEND | PG_BINARY); - if (fd < 0) - { - ereport(LOG, - (errcode_for_file_access(), - errmsg("could not write file \"%s\": %m", - file_name))); - return false; - } - - /* Loop until write buf_len bytes to the file. */ - do - { - ssize_t nwrite = write(fd, buf + off, buf_len - off); - - if (nwrite == -1) - { - if (errno == EINTR && tries++ < 3) - continue; - - success = false; - break; - } - off += nwrite; - } while (off < buf_len); - - if (!success) - ereport(LOG, - (errcode_for_file_access(), - errmsg("could not write file \"%s\": %m", file_name))); - - if (fd > 0) - CloseTransientFile(fd); - - return success; -} - -/* - * Try to locate query text in a dumped file for bucket_id. - * - * Returns: - * 1 Query sucessfully read, query_text will contain the query text. - * 0 Query not found. - * -1 I/O Error. - */ -int -read_query_buffer(int bucket_id, uint64 queryid, char *query_txt, size_t pos) -{ - int fd = 0; - char file_name[1024]; - unsigned char *buf = NULL; - ssize_t nread = 0; - int off = 0; - int tries = 0; - bool done = false; - bool found = false; - - snprintf(file_name, 1024, "%s", PGSM_TEXT_FILE); - fd = OpenTransientFile(file_name, O_RDONLY | PG_BINARY); - if (fd < 0) - goto exit; - - buf = (unsigned char *) palloc(MAX_QUERY_BUF); - while (!done) - { - off = 0; - /* read a chunck of MAX_QUERY_BUF size. */ - do - { - nread = read(fd, buf + off, MAX_QUERY_BUF - off); - if (nread == -1) - { - if (errno == EINTR && tries++ < 3) /* read() was interrupted, - * attempt to read again - * (max attempts=3) */ - continue; - - goto exit; - } - else if (nread == 0) /* EOF */ - { - done = true; - break; - } - - off += nread; - } while (off < MAX_QUERY_BUF); - - if (off == MAX_QUERY_BUF) - { - /* we have a chunck, scan it looking for queryid. */ - if (read_query(buf, queryid, query_txt, pos) != 0) - { - - found = true; - /* query was found, don't need to read another chunck. */ - break; - } - } - else - - /* - * Either done=true or file has a size not multiple of - * MAX_QUERY_BUF. It is safe to assume that the file was truncated - * or corrupted. - */ - break; - } - -exit: - if (fd < 0 || nread == -1) - ereport(LOG, - (errcode_for_file_access(), - errmsg("could not read file \"%s\": %m", - file_name))); - - if (fd >= 0) - CloseTransientFile(fd); - - if (buf) - pfree(buf); - - if (found) - return 1; - else if (fd == -1 || nread == -1) - return -1; /* I/O error. */ - else - return 0; /* Not found. */ -} static double time_diff(struct timeval end, struct timeval start) diff --git a/pg_stat_monitor.h b/pg_stat_monitor.h index dd66c9d..78d8183 100644 --- a/pg_stat_monitor.h +++ b/pg_stat_monitor.h @@ -27,6 +27,9 @@ #include #include +#include "lib/dshash.h" +#include "utils/dsa.h" + #include "access/hash.h" #include "catalog/pg_authid.h" #include "executor/instrument.h" @@ -179,20 +182,6 @@ typedef struct CallTime double sum_var_time; /* sum of variances in execution time in msec */ } CallTime; -/* - * Entry type for queries hash table (query ID). - * - * We use a hash table to keep track of query IDs that have their - * corresponding query text added to the query buffer (pgsm_query_shared_buffer). - * - * This allow us to avoid adding duplicated queries to the buffer, therefore - * leaving more space for other queries and saving some CPU. - */ -typedef struct pgssQueryEntry -{ - uint64 queryid; /* query identifier, also the key. */ - size_t query_pos; /* query location within query buffer */ -} pgssQueryEntry; typedef struct PlanInfo { @@ -216,6 +205,7 @@ typedef struct pgssHashKey typedef struct QueryInfo { uint64 parentid; /* parent queryid of current query */ + dsa_pointer parent_query; int64 type; /* type of query, options are query, info, * warning, error, fatal */ char application_name[APPLICATIONNAME_LEN]; @@ -322,7 +312,7 @@ typedef struct pgssEntry Counters counters; /* the statistics for this query */ int encoding; /* query text encoding */ slock_t mutex; /* protects the counters only */ - size_t query_pos; /* query location within query buffer */ + dsa_pointer query_pos; /* query location within query buffer */ } pgssEntry; /* @@ -353,10 +343,19 @@ typedef struct pgssSharedState * This allows us to avoid having a large file on disk that would also * slowdown queries to the pg_stat_monitor view. */ - bool overflow; size_t n_bucket_cycles; + int hash_tranche_id; + void *raw_dsa_area; + dshash_table_handle hash_handle; } pgssSharedState; +typedef struct pgsmLocalState +{ + pgssSharedState *shared_pgssState; + dsa_area *dsa; + dshash_table *shared_hash; +}pgsmLocalState; + #define ResetSharedState(x) \ do { \ x->cur_median_usage = ASSUMED_MEDIAN_INIT; \ @@ -418,27 +417,22 @@ void init_guc(void); GucVariable *get_conf(int i); /* hash_create.c */ +dsa_area *get_dsa_area_for_query_text(void); +dshash_table *get_pgssHash(void); +void pgsm_attach_shmem(void); bool IsHashInitialize(void); void pgss_shmem_startup(void); void pgss_shmem_shutdown(int code, Datum arg); int pgsm_get_bucket_size(void); pgssSharedState *pgsm_get_ss(void); -HTAB *pgsm_get_plan_hash(void); -HTAB *pgsm_get_hash(void); -HTAB *pgsm_get_query_hash(void); -HTAB *pgsm_get_plan_hash(void); void hash_entry_reset(void); void hash_query_entryies_reset(void); void hash_query_entries(); void hash_query_entry_dealloc(int new_bucket_id, int old_bucket_id, unsigned char *query_buffer[]); void hash_entry_dealloc(int new_bucket_id, int old_bucket_id, unsigned char *query_buffer); pgssEntry *hash_entry_alloc(pgssSharedState *pgss, pgssHashKey *key, int encoding); -Size hash_memsize(void); - -int read_query_buffer(int bucket_id, uint64 queryid, char *query_txt, size_t pos); -uint64 read_query(unsigned char *buf, uint64 queryid, char *query, size_t pos); +Size pgsm_ShmemSize(void); void pgss_startup(void); -void set_qbuf(unsigned char *); /* hash_query.c */ void pgss_startup(void);