diff --git a/contrib/pg_prewarm/Makefile b/contrib/pg_prewarm/Makefile index 7ad941e..88580d1 100644 --- a/contrib/pg_prewarm/Makefile +++ b/contrib/pg_prewarm/Makefile @@ -1,10 +1,10 @@ # contrib/pg_prewarm/Makefile MODULE_big = pg_prewarm -OBJS = pg_prewarm.o $(WIN32RES) +OBJS = pg_prewarm.o autoprewarm.o $(WIN32RES) EXTENSION = pg_prewarm -DATA = pg_prewarm--1.1.sql pg_prewarm--1.0--1.1.sql +DATA = pg_prewarm--1.1--1.2.sql pg_prewarm--1.1.sql pg_prewarm--1.0--1.1.sql PGFILEDESC = "pg_prewarm - preload relation data into system buffer cache" ifdef USE_PGXS diff --git a/contrib/pg_prewarm/autoprewarm.c b/contrib/pg_prewarm/autoprewarm.c new file mode 100644 index 0000000..eb99628 --- /dev/null +++ b/contrib/pg_prewarm/autoprewarm.c @@ -0,0 +1,1135 @@ +/*------------------------------------------------------------------------- + * + * autoprewarm.c + * Automatically prewarm the shared buffer pool when server restarts. + * + * Copyright (c) 2016-2017, PostgreSQL Global Development Group + * + * IDENTIFICATION + * contrib/autoprewarm.c + *------------------------------------------------------------------------- + */ + +#include "pg_prewarm.h" + +/* + * autoprewarm : + * + * What is it? + * =========== + * A bgworker which automatically records information about blocks which were + * present in buffer pool before server shutdown and then prewarm the buffer + * pool upon server restart with those blocks. + * + * How does it work? + * ================= + * When the shared library "pg_prewarm" is preloaded, a + * bgworker "autoprewarm" is launched immediately after the server has reached + * consistent state. The bgworker will start loading blocks recorded in the + * format BlockInfoRecord + * <> in + * $PGDATA/AUTOPREWARM_FILE, until there is no free buffer left in the buffer + * pool. This way we do not replace any new blocks which were loaded either by + * the recovery process or the querying clients. + * + * Once the "autoprewarm" bgworker has completed its prewarm task, it will + * start a new task to periodically dump the BlockInfoRecords related to blocks + * which are currently in shared buffer pool. Upon next server restart, the + * bgworker will prewarm the buffer pool by loading those blocks. The GUC + * pg_prewarm.dump_interval will control the dumping activity of the bgworker. + */ + +PG_FUNCTION_INFO_V1(launch_autoprewarm_dump); +PG_FUNCTION_INFO_V1(autoprewarm_dump_now); + +#define AT_PWARM_OFF -1 +#define AT_PWARM_DUMP_AT_SHUTDOWN_ONLY 0 +#define AT_PWARM_DEFAULT_DUMP_INTERVAL 300 + +#define AUTOPREWARM_FILE "autoprewarm.blocks" + +/* Primary functions */ +void _PG_init(void); +void autoprewarm_main(Datum main_arg); +static void dump_block_info_periodically(void); +static pid_t autoprewarm_dump_launcher(void); +static void setup_autoprewarm(BackgroundWorker *autoprewarm, + const char *worker_name, + const char *worker_function, + Datum main_arg, int restart_time, + int extra_flags); +void load_one_database(Datum main_arg); + +/* + * Signal Handlers. + */ + +static void SigtermHandler(SIGNAL_ARGS); +static void SighupHandler(SIGNAL_ARGS); +static void Sigusr1Handler(SIGNAL_ARGS); + +/* flags set by signal handlers */ +static volatile sig_atomic_t got_sigterm = false; +static volatile sig_atomic_t got_sighup = false; + +/* + * Signal handler for SIGTERM + * Set a flag to let the main loop to terminate, and set our latch to wake it + * up. + */ +static void +SigtermHandler(SIGNAL_ARGS) +{ + int save_errno = errno; + + got_sigterm = true; + + if (MyProc) + SetLatch(&MyProc->procLatch); + + errno = save_errno; +} + +/* + * Signal handler for SIGHUP + * Set a flag to tell the process to reread the config file, and set our + * latch to wake it up. + */ +static void +SighupHandler(SIGNAL_ARGS) +{ + int save_errno = errno; + + got_sighup = true; + + if (MyProc) + SetLatch(&MyProc->procLatch); + + errno = save_errno; +} + +/* + * Signal handler for SIGUSR1. + * The prewarm sub-workers will notify with SIGUSR1 on their startup/shutdown. + */ +static void +Sigusr1Handler(SIGNAL_ARGS) +{ + int save_errno = errno; + + if (MyProc) + SetLatch(&MyProc->procLatch); + + errno = save_errno; +} + +/* ============================================================================ + * ============== types and variables used by autoprewam ============= + * ============================================================================ + */ + +/* + * Meta-data of each persistent block which is dumped and used to load. + */ +typedef struct BlockInfoRecord +{ + Oid database; /* database */ + Oid spcNode; /* tablespace */ + Oid filenode; /* relation's filenode. */ + ForkNumber forknum; /* fork number */ + BlockNumber blocknum; /* block number */ +} BlockInfoRecord; + +/* + * Tasks performed by autoprewarm workers. + */ +typedef enum +{ + TASK_PREWARM_BUFFERPOOL, /* prewarm the buffer pool. */ + TASK_DUMP_BUFFERPOOL_INFO, /* dump the buffer pool block info. */ + TASK_DUMP_IMMEDIATE_ONCE, /* dump the buffer pool block info immediately + * once. */ + TASK_END /* no more tasks to do. */ +} AutoPrewarmTask; + +/* + * Shared state information about the running autoprewarm bgworker. + */ +typedef struct AutoPrewarmSharedState +{ + LWLock *lock; /* protects SharedState */ + AutoPrewarmTask current_task; /* current tasks performed by + * autoprewarm workers. */ + bool is_bgworker_running; /* if set can't start another worker. */ + bool can_do_prewarm; /* if set can't do prewarm task. */ + + /* dsa used to distribute block_infos among subworkers of prewarm task. */ + dsa_handle apw_dsa_handle; + uint32 apw_num_block_infos; /* total number of sorted block_infos + * in dsa. */ + dsa_pointer apw_block_infos;/* dsa memory where above block_infos are + * stored. */ +} AutoPrewarmSharedState; + +static dsa_area *AutoPrewarmDSA = NULL; + +static AutoPrewarmSharedState *state = NULL; + +/* + * Kind of BlockInfoRecord in AUTOPREWARM_FILE file. + */ +typedef enum +{ + BLKTYPE_NEW_DATABASE, /* first BlockInfoRecord of new database. */ + BLKTYPE_NEW_RELATION, /* first BlockInfoRecord of new relation. */ + BLKTYPE_NEW_FORK, /* first BlockInfoRecord of new fork file. */ + BLKTYPE_NEW_BLOCK, /* any next BlockInfoRecord. */ + BLKTYPE_END /* No More BlockInfoRecords available in dump + * file. */ +} BlkType; + +/* GUC variable which control the dump activity of autoprewarm. */ +static int dump_interval = 0; + +/* + * GUC variable which says to which database we have to connect when + * BlockInfoRecord belongs to global objects. + */ +static char *default_database; + +/* compare member elements to check if they are not equal. */ +#define cmp_member_elem(fld) \ +do { \ + if (a->fld < b->fld) \ + return -1; \ + else if (a->fld > b->fld) \ + return 1; \ +} while(0); + +/* + * blockinfo_cmp - compare function used for qsort(). + */ +static int +blockinfo_cmp(const void *p, const void *q) +{ + BlockInfoRecord *a = (BlockInfoRecord *) p; + BlockInfoRecord *b = (BlockInfoRecord *) q; + + cmp_member_elem(database); + cmp_member_elem(spcNode); + cmp_member_elem(filenode); + cmp_member_elem(forknum); + cmp_member_elem(blocknum); + return 0; +} + +/* ============================================================================ + * ===================== prewarm part of autoprewarm ======================= + * ============================================================================ + */ + +/* + * reset_shm_state - on_shm_exit reset the prewarm state. + */ + +static void +reset_shm_state(int code, Datum arg) +{ + state->is_bgworker_running = false; + state->current_task = TASK_END; + if (AutoPrewarmDSA) + { + if (state->apw_block_infos != InvalidDsaPointer) + { + dsa_free(AutoPrewarmDSA, state->apw_block_infos); + state->apw_block_infos = InvalidDsaPointer; + state->apw_num_block_infos = 0; + } + + dsa_detach(AutoPrewarmDSA); + AutoPrewarmDSA = NULL; + } +} + +/* + * get_autoprewarm_task - get next task allowed and to be performed by the + * autoprewarm worker. + */ +static AutoPrewarmTask +get_autoprewarm_task(AutoPrewarmTask todo_task) +{ + bool found = false; + + LWLockAcquire(AddinShmemInitLock, LW_EXCLUSIVE); + state = ShmemInitStruct("autoprewarm", + sizeof(AutoPrewarmSharedState), + &found); + if (!found) + { + /* First time through ... */ + state->lock = &(GetNamedLWLockTranche("pg_autoprewarm"))->lock; + state->current_task = TASK_END; + state->is_bgworker_running = false; + state->can_do_prewarm = true; + } + + LWLockRelease(AddinShmemInitLock); + LWLockAcquire(state->lock, LW_EXCLUSIVE); + + /* + * If already a bgworker is running we cannot run another. But if task is + * to just dump immediate and there is no prewarm happening we can go + * further. + */ + if (state->is_bgworker_running && + (todo_task != TASK_DUMP_IMMEDIATE_ONCE || + state->current_task != TASK_PREWARM_BUFFERPOOL)) + { + LWLockRelease(state->lock); + return TASK_END; + } + + /* + * If asked to do prewarm check can we do so. We avoid prewarm if its + * already done on startup. + */ + if (todo_task == TASK_PREWARM_BUFFERPOOL && !state->can_do_prewarm) + todo_task = TASK_DUMP_BUFFERPOOL_INFO; + + /* + * For now if there was a previous attempt to prewarm or dump any further + * request to prewarm will not be entertained. + */ + state->can_do_prewarm = false; + + if (todo_task != TASK_DUMP_IMMEDIATE_ONCE) + { + state->is_bgworker_running = true; + state->current_task = todo_task; + on_shmem_exit(reset_shm_state, 0); + } + + LWLockRelease(state->lock); + return todo_task; +} + +/* + * getnextblockinfo -- given a BlkType get its next BlockInfoRecord. + */ +static BlkType +getnextblockinfo(BlockInfoRecord *toload_block, uint32 curr_blockinfo_pos, + BlkType reqblock, uint32 *next_blockinfo_pos) +{ + BlkType nextblk; + + while (true) + { + /* get next block. */ + if (curr_blockinfo_pos >= state->apw_num_block_infos) + return BLKTYPE_END; /* No more valid entry hence stop processing. */ + + if (toload_block[curr_blockinfo_pos].database != + toload_block[curr_blockinfo_pos + 1].database) + nextblk = BLKTYPE_NEW_DATABASE; + else if (toload_block[curr_blockinfo_pos].filenode != + toload_block[curr_blockinfo_pos + 1].filenode) + nextblk = BLKTYPE_NEW_RELATION; + else if (toload_block[curr_blockinfo_pos].forknum != + toload_block[curr_blockinfo_pos + 1].forknum) + nextblk = BLKTYPE_NEW_FORK; + else + nextblk = BLKTYPE_NEW_BLOCK; + + if (nextblk <= reqblock) + { + *next_blockinfo_pos = curr_blockinfo_pos + 1; + return nextblk; + } + + curr_blockinfo_pos++; + } +} + +/* + * connect_to_db -- connect to the given dbid. + * + * For global objects the dbid will be InvalidOid, connect to user given + * default_database and try to load those blocks. + */ +static void +connect_to_db(Oid dbid) +{ + if (!OidIsValid(dbid)) + BackgroundWorkerInitializeConnection(default_database, NULL); + else + BackgroundWorkerInitializeConnectionByOid(dbid, InvalidOid); + SetCurrentStatementStartTimestamp(); + StartTransactionCommand(); + SPI_connect(); + PushActiveSnapshot(GetTransactionSnapshot()); +} + +/* + * load_one_database -- start of prewarm sub-worker, this will try to load + * blocks of one database starting from block info position passed by main + * prewarm worker. + */ +void +load_one_database(Datum main_arg) +{ + uint32 curr_pos, + next_pos; + BlockInfoRecord *toload_block; + Relation rel = NULL; + bool have_dbconnection = false; + BlkType loadblocktype; + BlockNumber nblocks = 0; + bool found; + + /* Establish signal handlers before unblocking signals. */ + pqsignal(SIGTERM, SigtermHandler); + pqsignal(SIGHUP, SighupHandler); + + /* + * We're now ready to receive signals + */ + BackgroundWorkerUnblockSignals(); + + curr_pos = DatumGetInt64(main_arg); + + LWLockAcquire(AddinShmemInitLock, LW_EXCLUSIVE); + state = ShmemInitStruct("autoprewarm", + sizeof(AutoPrewarmSharedState), + &found); + LWLockRelease(AddinShmemInitLock); + + Assert(found); + Assert(state->apw_dsa_handle); + + AutoPrewarmDSA = dsa_attach(state->apw_dsa_handle); + toload_block = (BlockInfoRecord *) + dsa_get_address(AutoPrewarmDSA, state->apw_block_infos); + + loadblocktype = BLKTYPE_NEW_DATABASE; + next_pos = curr_pos; + + while (loadblocktype != BLKTYPE_END) + { + Buffer buf; + Oid reloid; + + /* + * Load the block only if there exist a free buffer. We do not want to + * replace a block already in buffer pool. + */ + if (!have_free_buffer()) + goto end_load; + + if (got_sigterm) + goto end_load; + + switch (loadblocktype) + { + case BLKTYPE_NEW_DATABASE: + + if (have_dbconnection) + goto end_load; /* blocks belong to a new database, + * lets end the loading process. */ + + /* + * connect to the database. + */ + connect_to_db(toload_block[next_pos].database); + have_dbconnection = true; + + case BLKTYPE_NEW_RELATION: + + /* + * release lock on previous relation. + */ + if (rel) + { + relation_close(rel, AccessShareLock); + rel = NULL; + } + + loadblocktype = BLKTYPE_NEW_RELATION; + + /* + * lock new relation. + */ + reloid = + RelidByRelfilenode(toload_block[next_pos].spcNode, + toload_block[next_pos].filenode); + + if (!OidIsValid(reloid)) + break; + + rel = try_relation_open(reloid, AccessShareLock); + if (!rel) + break; + RelationOpenSmgr(rel); + + case BLKTYPE_NEW_FORK: + + /* + * check if fork exists and if block is within the range + */ + loadblocktype = BLKTYPE_NEW_FORK; + if (toload_block[next_pos].forknum > InvalidForkNumber && + toload_block[next_pos].forknum <= MAX_FORKNUM && + !smgrexists(rel->rd_smgr, toload_block[next_pos].forknum)) + break; + nblocks = RelationGetNumberOfBlocksInFork(rel, + toload_block[next_pos].forknum); + case BLKTYPE_NEW_BLOCK: + + /* check if blocknum is valid and with in fork file size. */ + if (toload_block[next_pos].blocknum >= nblocks) + { + /* move to next forknum. */ + loadblocktype = BLKTYPE_NEW_FORK; + break; + } + + buf = ReadBufferExtended(rel, toload_block[next_pos].forknum, + toload_block[next_pos].blocknum, RBM_NORMAL, + NULL); + if (BufferIsValid(buf)) + { + ReleaseBuffer(buf); + } + + loadblocktype = BLKTYPE_NEW_BLOCK; + break; + + case BLKTYPE_END: + Assert(0); /* Should not be here! */ + } + + curr_pos = next_pos; + loadblocktype = getnextblockinfo(toload_block, curr_pos, loadblocktype, + &next_pos); + } + +end_load: + + dsa_detach(AutoPrewarmDSA); + /* release lock on previous relation. */ + if (rel) + { + relation_close(rel, AccessShareLock); + rel = NULL; + } + + if (have_dbconnection) + { + SPI_finish(); + PopActiveSnapshot(); + CommitTransactionCommand(); + } + return; +} + +/* + * launch_prewarm_subworker -- register a dynamic worker to load the blocks + * starting from next_db_pos. We wait until the worker has stopped. + */ +static void +launch_prewarm_subworker(uint32 next_db_pos) +{ + BackgroundWorker worker; + BackgroundWorkerHandle *handle = NULL; + BgwHandleStatus status; + + setup_autoprewarm(&worker, "autoprewarm", "load_one_database", + Int64GetDatum(next_db_pos), BGW_NEVER_RESTART, + BGWORKER_BACKEND_DATABASE_CONNECTION); + /* set bgw_notify_pid so that we can use WaitForBackgroundWorkerShutdown */ + worker.bgw_notify_pid = MyProcPid; + + if (!RegisterDynamicBackgroundWorker(&worker, &handle)) + { + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_RESOURCES), + errmsg("registering dynamic bgworker autoprewarm failed"), + errhint("Consider increasing configuration parameter " + "\"max_worker_processes\"."))); + } + + status = WaitForBackgroundWorkerShutdown(handle); + if (status == BGWH_STOPPED) + return; + + if (status == BGWH_POSTMASTER_DIED) + { + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_RESOURCES), + errmsg("cannot start bgworker autoprewarm without postmaster"), + errhint("Kill all remaining database processes and restart" + " the database."))); + } + + Assert(0); +} + +/* + * prewarm_buffer_pool - the main routine which prewarm the buffer pool. + * + * The prewarm bgworker will first load all of the BlockInfoRecord's in + * $PGDATA/AUTOPREWARM_FILE to a dsa. And those BlockInfoRecords are further + * separated based on their database. And for each group of BlockInfoRecords a + * sub-workers will be launched to load corresponding blocks. Each sub-worker + * will be launched in sequential order only after the previous sub-worker has + * finished its job. + */ +static void +prewarm_buffer_pool(void) +{ + static char dump_file_path[MAXPGPATH]; + FILE *file = NULL; + uint32 *next_db_pos; + size_t next_db_pos_size; + uint32 this_dbs_elements = 0, + num_elements, + num_db = 0, + i; + Oid prev_database; + BlockInfoRecord *blkinfo; + + snprintf(dump_file_path, sizeof(dump_file_path), "%s", + AUTOPREWARM_FILE); + + file = fopen(dump_file_path, PG_BINARY_R); + if (!file) + return; /* No file to load. */ + + if (!state->apw_dsa_handle) + { + AutoPrewarmDSA = dsa_create(state->lock->tranche); + state->apw_dsa_handle = dsa_get_handle(AutoPrewarmDSA); + } + else + AutoPrewarmDSA = dsa_attach(state->apw_dsa_handle); + + if (fscanf(file, "<<%u>>", &num_elements) != 1) + { + fclose(file); + ereport(ERROR, + (errcode_for_file_access(), + errmsg("Error reading num of elements in \"%s\" for" + " autoprewarm : %m", dump_file_path))); + } + + state->apw_block_infos = + dsa_allocate_extended(AutoPrewarmDSA, + sizeof(BlockInfoRecord) * num_elements, + DSA_ALLOC_NO_OOM); + if (state->apw_block_infos == InvalidDsaPointer) + { + fclose(file); + dsa_detach(AutoPrewarmDSA); + AutoPrewarmDSA = NULL; + return; + } + + state->apw_num_block_infos = num_elements; + + blkinfo = (BlockInfoRecord *) + dsa_get_address(AutoPrewarmDSA, state->apw_block_infos); + + next_db_pos_size = 64; + next_db_pos = (uint32 *) palloc(sizeof(uint32) * next_db_pos_size); + + /* read and fill block infos */ + for (i = 0; i < num_elements; i++, blkinfo++) + { + /* get next block. */ + if (5 != fscanf(file, "%u,%u,%u,%u,%u\n", &blkinfo->database, + &blkinfo->spcNode, &blkinfo->filenode, + (uint32 *) &blkinfo->forknum, + &blkinfo->blocknum)) + break; /* no more records found. */ + if (i == 0) + { + next_db_pos[num_db++] = 0; + prev_database = blkinfo->database; + } + else if (prev_database != blkinfo->database) + { + if (num_db >= next_db_pos_size) + { + next_db_pos_size *= 2; + next_db_pos = (uint32 *) repalloc(next_db_pos, + sizeof(uint32) * next_db_pos_size); + } + + next_db_pos[num_db++] = this_dbs_elements; + this_dbs_elements = 0; + prev_database = blkinfo->database; + } + + this_dbs_elements++; + } + + fclose(file); + i = 0; + + /* get next database's first block info's position. */ + while (!got_sigterm && i < num_db) + { + /* + * Register a sub-worker to load new database's block. Wait until the + * sub-worker finish its job before launching next subworker. + */ + launch_prewarm_subworker(next_db_pos[i++]); + } + + pfree(next_db_pos); + + if (AutoPrewarmDSA) + { + if (state->apw_block_infos != InvalidDsaPointer) + { + dsa_free(AutoPrewarmDSA, state->apw_block_infos); + state->apw_block_infos = InvalidDsaPointer; + state->apw_num_block_infos = 0; + } + + dsa_detach(AutoPrewarmDSA); + AutoPrewarmDSA = NULL; + } + + ereport(LOG, (errmsg("autoprewarm load task ended"))); + return; +} + +/* ============================================================================ + * ============= buffer pool info dump part of autoprewarm =============== + * ============================================================================ + */ + +/* This sub-module is for periodically dumping buffer pool's block info into + * a dump file AUTOPREWARM_FILE. + * Each entry of block info looks like this: + * and we shall call it + * as BlockInfoRecord. Note we write in the text form so that the dump + * information is readable and if necessary can be carefully edited. + * + * The prewarm task will read these blockInfoRecord one by one in sequence and + * distribute it among its sub workers to load corresponding blocks. + */ + +/* + * dump_now - the main routine which goes through each buffer header of buffer + * pool and dumps their meta data. We Sort these data and then dump them. + * Sorting is necessary as it facilitates sequential read during load. + */ +static uint32 +dump_now(void) +{ + static char dump_file_path[MAXPGPATH], + transient_dump_file_path[MAXPGPATH]; + uint32 i; + int ret, + buflen; + uint32 num_blocks; + BlockInfoRecord *block_info_array; + BufferDesc *bufHdr; + int fd; + char buf[1024]; + + block_info_array = + (BlockInfoRecord *) palloc(sizeof(BlockInfoRecord) * NBuffers); + + for (num_blocks = 0, i = 0; i < NBuffers; i++) + { + uint32 buf_state; + + /* + * In case of a SIGHUP, just reload the configuration. + */ + if (got_sighup) + { + got_sighup = false; + ProcessConfigFile(PGC_SIGHUP); + } + + /* Have we been asked to stop dump? */ + if (dump_interval == AT_PWARM_OFF) + { + free(block_info_array); + return 0; + } + + bufHdr = GetBufferDescriptor(i); + + /* lock each buffer header before inspecting. */ + buf_state = LockBufHdr(bufHdr); + + if (buf_state & BM_TAG_VALID) + { + block_info_array[num_blocks].database = bufHdr->tag.rnode.dbNode; + block_info_array[num_blocks].spcNode = bufHdr->tag.rnode.spcNode; + block_info_array[num_blocks].filenode = bufHdr->tag.rnode.relNode; + block_info_array[num_blocks].forknum = bufHdr->tag.forkNum; + block_info_array[num_blocks].blocknum = bufHdr->tag.blockNum; + ++num_blocks; + } + + UnlockBufHdr(bufHdr, buf_state); + } + + /* + * sort the block number to increase chance of sequential reads during + * load. + */ + pg_qsort(block_info_array, num_blocks, sizeof(BlockInfoRecord), + blockinfo_cmp); + + snprintf(transient_dump_file_path, sizeof(dump_file_path), + "%s.%d", AUTOPREWARM_FILE, MyProcPid); + + fd = OpenTransientFile(transient_dump_file_path, + O_CREAT | O_WRONLY | O_TRUNC, 0666); + if (fd < 0) + ereport(ERROR, + (errcode_for_file_access(), + errmsg("autoprewarm: could not open \"%s\": %m", + dump_file_path))); + + snprintf(dump_file_path, sizeof(dump_file_path), + "%s", AUTOPREWARM_FILE); + buflen = sprintf(buf, "<<%u>>\n", num_blocks); + if (write(fd, buf, buflen) < buflen) + ereport(ERROR, + (errcode_for_file_access(), + errmsg("autoprewarm: error writing to \"%s\" : %m", + dump_file_path))); + + for (i = 0; i < num_blocks; i++) + { + /* + * In case of a SIGHUP, just reload the configuration. + */ + if (got_sighup) + { + got_sighup = false; + ProcessConfigFile(PGC_SIGHUP); + } + + /* Have we been asked to stop dump? */ + if (dump_interval == AT_PWARM_OFF) + { + free(block_info_array); + CloseTransientFile(fd); + unlink(transient_dump_file_path); + return 0; + } + + buflen = sprintf(buf, "%u,%u,%u,%u,%u\n", + block_info_array[i].database, + block_info_array[i].spcNode, + block_info_array[i].filenode, + (uint32) block_info_array[i].forknum, + block_info_array[i].blocknum); + + if (write(fd, buf, buflen) < buflen) + { + CloseTransientFile(fd); + ereport(ERROR, + (errcode_for_file_access(), + errmsg("autoprewarm: error writing to \"%s\" : %m", + dump_file_path))); + } + } + + pfree(block_info_array); + + /* + * rename transient_dump_file_path to dump_file_path to make things + * permanent. + */ + ret = CloseTransientFile(fd); + if (ret != 0) + ereport(ERROR, + (errcode_for_file_access(), + errmsg("autoprewarm: error closing \"%s\" : %m", + transient_dump_file_path))); + (void) durable_rename(transient_dump_file_path, dump_file_path, LOG); + + ereport(LOG, (errmsg("autoprewarm: saved metadata info of %d blocks", + num_blocks))); + return num_blocks; +} + +/* + * dump_block_info_periodically - at regular intervals, which is defined by GUC + * dump_interval, dump the info of blocks which are present in buffer pool. + */ +void +dump_block_info_periodically(void) +{ + TimestampTz last_dump_time = GetCurrentTimestamp(); + + while (!got_sigterm) + { + int rc; + struct timeval nap; + + nap.tv_sec = AT_PWARM_DEFAULT_DUMP_INTERVAL; + nap.tv_usec = 0; + + /* Has been set not to dump. Nothing more to do. */ + if (dump_interval == AT_PWARM_OFF) + return; + + if (dump_interval > AT_PWARM_DUMP_AT_SHUTDOWN_ONLY) + { + TimestampTz current_time = GetCurrentTimestamp(); + + if (TimestampDifferenceExceeds(last_dump_time, + current_time, + (dump_interval * 1000))) + { + dump_now(); + if (got_sigterm) + return; /* got shutdown signal just after a dump. And, + * I think better to return now. */ + last_dump_time = GetCurrentTimestamp(); + nap.tv_sec = dump_interval; + nap.tv_usec = 0; + } + else + { + long secs; + int usecs; + + TimestampDifference(last_dump_time, current_time, + &secs, &usecs); + nap.tv_sec = dump_interval - secs; + nap.tv_usec = 0; + } + } + + ResetLatch(&MyProc->procLatch); + rc = WaitLatch(&MyProc->procLatch, + WL_LATCH_SET | WL_TIMEOUT | WL_POSTMASTER_DEATH, + (nap.tv_sec * 1000L) + (nap.tv_usec / 1000L), + PG_WAIT_EXTENSION); + + if (rc & WL_POSTMASTER_DEATH) + proc_exit(1); + + /* + * In case of a SIGHUP, just reload the configuration. + */ + if (got_sighup) + { + got_sighup = false; + ProcessConfigFile(PGC_SIGHUP); + } + } + + /* One last block meta info dump while postmaster shutdown. */ + if (dump_interval != AT_PWARM_OFF) + dump_now(); +} + +/* + * autoprewarm_main -- the main entry point of autoprewarm bgworker process. + */ +void +autoprewarm_main(Datum main_arg) +{ + AutoPrewarmTask next_task; + + /* Establish signal handlers before unblocking signals. */ + pqsignal(SIGTERM, SigtermHandler); + pqsignal(SIGHUP, SighupHandler); + pqsignal(SIGUSR1, Sigusr1Handler); + + + /* We're now ready to receive signals */ + BackgroundWorkerUnblockSignals(); + + next_task = get_autoprewarm_task(DatumGetInt32(main_arg)); + + ereport(LOG, (errmsg("autoprewarm has started"))); + + /* + * **** perform autoprewarm's next task **** + */ + if (next_task == TASK_PREWARM_BUFFERPOOL) + { + prewarm_buffer_pool(); + /* prewarm is done lets move to TASK_DUMP_BUFFERPOOL_INFO. */ + state->current_task = TASK_DUMP_BUFFERPOOL_INFO; + next_task = TASK_DUMP_BUFFERPOOL_INFO; + } + + if (next_task == TASK_DUMP_BUFFERPOOL_INFO) + { + dump_block_info_periodically(); + + /* + * down grade to TASK_DUMP_IMMEDIATE_ONCE so others can start + * TASK_DUMP_BUFFERPOOL_INFO + */ + state->current_task = TASK_DUMP_IMMEDIATE_ONCE; + } + + ereport(LOG, (errmsg("autoprewarm shutting down"))); +} + +/* ============================================================================ + * ============= extension's entry functions/utilities =================== + * ============================================================================ + */ + +/* Register autoprewarm load bgworker. */ +static void +setup_autoprewarm(BackgroundWorker *autoprewarm, const char *worker_name, + const char *worker_function, Datum main_arg, int restart_time, + int extra_flags) +{ + MemSet(autoprewarm, 0, sizeof(BackgroundWorker)); + autoprewarm->bgw_flags = BGWORKER_SHMEM_ACCESS | extra_flags; + + /* Register the autoprewarm background worker */ + autoprewarm->bgw_start_time = BgWorkerStart_ConsistentState; + autoprewarm->bgw_restart_time = restart_time; + strcpy(autoprewarm->bgw_library_name, "pg_prewarm"); + strcpy(autoprewarm->bgw_function_name, worker_function); + strncpy(autoprewarm->bgw_name, worker_name, BGW_MAXLEN); + autoprewarm->bgw_main_arg = main_arg; +} + +/* Extension's entry point. */ +void +_PG_init(void) +{ + BackgroundWorker autoprewarm; + + /* Define custom GUC variables. */ + DefineCustomIntVariable("pg_prewarm.dump_interval", + "Sets the maximum time between two buffer pool dumps", + "If set to Zero, timer based dumping is disabled." + " If set to -1, stops the running autoprewarm.", + &dump_interval, + AT_PWARM_DEFAULT_DUMP_INTERVAL, + AT_PWARM_OFF, INT_MAX / 1000, + PGC_SIGHUP, + GUC_UNIT_S, + NULL, + NULL, + NULL); + + DefineCustomStringVariable("pg_prewarm.default_database", + "default database to connect if dump has not recorded same.", + NULL, + &default_database, + "postgres", + PGC_POSTMASTER, + 0, + NULL, + NULL, + NULL); + EmitWarningsOnPlaceholders("pg_prewarm"); + + /* if not run as a preloaded library, nothing more to do here! */ + if (!process_shared_preload_libraries_in_progress) + return; + + /* Request additional shared resources */ + RequestAddinShmemSpace(MAXALIGN(sizeof(AutoPrewarmSharedState))); + RequestNamedLWLockTranche("pg_autoprewarm", 1); + + /* Has been set not to prewarm/dump. Nothing more to do. */ + if (dump_interval == AT_PWARM_OFF) + return; + + /* Register autoprewarm load. */ + setup_autoprewarm(&autoprewarm, "autoprewarm", "autoprewarm_main", + Int32GetDatum(TASK_PREWARM_BUFFERPOOL), 0, 0); + RegisterBackgroundWorker(&autoprewarm); +} + +/* + * Dynamically launch an autoprewarm dump worker. + */ +static pid_t +autoprewarm_dump_launcher(void) +{ + BackgroundWorker worker; + BackgroundWorkerHandle *handle; + BgwHandleStatus status; + pid_t pid; + + setup_autoprewarm(&worker, "autoprewarm", "autoprewarm_main", + Int32GetDatum(TASK_DUMP_BUFFERPOOL_INFO), 0, 0); + + /* set bgw_notify_pid so that we can use WaitForBackgroundWorkerStartup */ + worker.bgw_notify_pid = MyProcPid; + + if (!RegisterDynamicBackgroundWorker(&worker, &handle)) + { + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_RESOURCES), + errmsg("registering dynamic bgworker \"autoprewarm\" failed"), + errhint("Consider increasing configuration parameter " + "\"max_worker_processes\"."))); + } + + status = WaitForBackgroundWorkerStartup(handle, &pid); + if (status == BGWH_STOPPED) + { + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_RESOURCES), + errmsg("could not start autoprewarm dump bgworker"), + errhint("More details may be available in the server log."))); + } + + if (status == BGWH_POSTMASTER_DIED) + { + ereport(ERROR, + (errcode(ERRCODE_INSUFFICIENT_RESOURCES), + errmsg("cannot start bgworker autoprewarm without postmaster"), + errhint("Kill all remaining database processes and restart" + " the database."))); + } + + Assert(status == BGWH_STARTED); + return pid; +} + +/* + * The C-Language entry function to launch autoprewarm dump bgworker. + */ +Datum +launch_autoprewarm_dump(PG_FUNCTION_ARGS) +{ + pid_t pid; + + /* Has been set not to prewarm/dump. Nothing more to do. */ + if (dump_interval == AT_PWARM_OFF) + PG_RETURN_NULL(); + + pid = autoprewarm_dump_launcher(); + PG_RETURN_INT32(pid); +} + +/* + * The C-Language entry function to dump immediately. + */ +Datum +autoprewarm_dump_now(PG_FUNCTION_ARGS) +{ + AutoPrewarmTask next_task; + + /* dump only if prewarm is not in progress. */ + next_task = get_autoprewarm_task(TASK_DUMP_IMMEDIATE_ONCE); + if (next_task == TASK_DUMP_IMMEDIATE_ONCE) + PG_RETURN_INT64(dump_now()); + PG_RETURN_NULL(); +} diff --git a/contrib/pg_prewarm/pg_prewarm--1.1--1.2.sql b/contrib/pg_prewarm/pg_prewarm--1.1--1.2.sql new file mode 100644 index 0000000..6c35fb7 --- /dev/null +++ b/contrib/pg_prewarm/pg_prewarm--1.1--1.2.sql @@ -0,0 +1,14 @@ +/* contrib/pg_prewarm/pg_prewarm--1.0--1.1.sql */ + +-- complain if script is sourced in psql, rather than via ALTER EXTENSION +\echo Use "ALTER EXTENSION pg_prewarm UPDATE TO '1.2'" to load this file. \quit + +CREATE FUNCTION launch_autoprewarm_dump() +RETURNS pg_catalog.int4 STRICT +AS 'MODULE_PATHNAME', 'launch_autoprewarm_dump' +LANGUAGE C; + +CREATE FUNCTION autoprewarm_dump_now() +RETURNS pg_catalog.int8 STRICT +AS 'MODULE_PATHNAME', 'autoprewarm_dump_now' +LANGUAGE C; diff --git a/contrib/pg_prewarm/pg_prewarm.control b/contrib/pg_prewarm/pg_prewarm.control index cf2fb92..40e3add 100644 --- a/contrib/pg_prewarm/pg_prewarm.control +++ b/contrib/pg_prewarm/pg_prewarm.control @@ -1,5 +1,5 @@ # pg_prewarm extension comment = 'prewarm relation data' -default_version = '1.1' +default_version = '1.2' module_pathname = '$libdir/pg_prewarm' relocatable = true diff --git a/contrib/pg_prewarm/pg_prewarm.h b/contrib/pg_prewarm/pg_prewarm.h new file mode 100644 index 0000000..9e2a6e6 --- /dev/null +++ b/contrib/pg_prewarm/pg_prewarm.h @@ -0,0 +1,43 @@ +/* + * contrib/pg_prewarm/pg_prewarm.h + */ +#ifndef __PG_PREWARM_H__ +#define __PG_PREWARM_H__ +#include "postgres.h" + +#include +#include + +/* These are always necessary for a bgworker. */ +#include "miscadmin.h" +#include "postmaster/bgworker.h" +#include "storage/ipc.h" +#include "storage/latch.h" +#include "storage/lwlock.h" +#include "storage/proc.h" +#include "storage/shmem.h" + +/* These are necessary for prewarm utilities. */ +#include "access/heapam.h" +#include "access/xact.h" +#include "catalog/catalog.h" +#include "catalog/pg_class.h" +#include "catalog/pg_type.h" +#include "executor/spi.h" +#include "fmgr.h" +#include "miscadmin.h" +#include "port/atomics.h" +#include "pgstat.h" +#include "storage/bufmgr.h" +#include "storage/buf_internals.h" +#include "storage/smgr.h" +#include "utils/acl.h" +#include "utils/builtins.h" +#include "utils/guc.h" +#include "utils/lsyscache.h" +#include "utils/memutils.h" +#include "utils/rel.h" +#include "utils/relfilenodemap.h" +#include "utils/resowner.h" + +#endif /* __PG_PREWARM_H__ */ diff --git a/doc/src/sgml/pgprewarm.sgml b/doc/src/sgml/pgprewarm.sgml index c090401..1538446 100644 --- a/doc/src/sgml/pgprewarm.sgml +++ b/doc/src/sgml/pgprewarm.sgml @@ -10,7 +10,9 @@ The pg_prewarm module provides a convenient way to load relation data into either the operating system buffer cache - or the PostgreSQL buffer cache. + or the PostgreSQL buffer cache. Additionally, an + automatic prewarming of the server buffers is supported whenever the server + restarts. @@ -55,6 +57,102 @@ pg_prewarm(regclass, mode text default 'buffer', fork text default 'main', cache. For these reasons, prewarming is typically most useful at startup, when caches are largely empty. + + +launch_autoprewarm_dump() RETURNS int4 + + + + This is a SQL callable function to launch the autoprewarm + worker to dump the buffer pool information at regular interval. In a server, + we can only run one autoprewarm worker so if worker sees + another existing worker it will exit immediately. The return value is pid of + the worker which has been launched. + + + +autoprewarm_dump_now() RETURNS int8 + + + + This is a SQL callable function to dump buffer pool information immediately + once by a backend. This can work in parallel + with the autoprewarm worker while it is dumping. + The return value is the number of blocks info dumped. + + + + + autoprewarm + + + A bgworker which automatically records information about blocks which were + present in buffer pool before server shutdown and then prewarm the buffer + pool upon server restart with those blocks. + + + + When the shared library pg_prewarm is preloaded via + in postgresql.conf, + a bgworker autoprewarm is launched immediately after the + server has reached a consistent state. The bgworker will start loading blocks + recorded in $PGDATA/autoprewarm.blocks until there is a + free buffer left in the buffer pool. This way we do not replace any new + blocks which were loaded either by the recovery process or the querying + clients. + + + + Once the autoprewarm bgworker has completed its prewarm + task, it will start a new task to periodically dump the information about + blocks which are currently in shared buffer pool. Upon next server restart, + the bgworker will prewarm the buffer pool by loading those blocks. The GUC + pg_prewarm.dump_interval will control the dumping activity + of the bgworker. + + + + + Configuration Parameters + + + + + pg_prewarm.dump_interval (int) + + pg_prewarm.dump_interval configuration parameter + + + + + This is valid only for autoprewarm. The minimum number + of seconds between two buffer pool's block information dump. The default + is 300 seconds. It also takes special values. If set to 0 then timer + based dump is disabled, it dumps only while the server is shutting down. + If set to -1, the running autoprewarm will be stopped. + + + + + + + + + pg_prewarm.default_database (string) + + pg_prewarm.default_database configuration parameter + + + + + This is valid only for autoprewarm. The blocks of + global objects will not have a database associated with them. The + default_database will be used to connect and preload + such blocks. + + + + diff --git a/src/backend/storage/buffer/freelist.c b/src/backend/storage/buffer/freelist.c index 5d0a636..06a34a7 100644 --- a/src/backend/storage/buffer/freelist.c +++ b/src/backend/storage/buffer/freelist.c @@ -169,6 +169,23 @@ ClockSweepTick(void) } /* + * have_free_buffer -- a lockless check to see if there is a free buffer in + * buffer pool. + * + * If the result is true that will become stale once free buffers are moved out + * by other operations, so the caller who strictly want to use a free buffer + * should not call this. + */ +bool +have_free_buffer() +{ + if (StrategyControl->firstFreeBuffer >= 0) + return true; + else + return false; +} + +/* * StrategyGetBuffer * * Called by the bufmgr to get the next candidate buffer to use in diff --git a/src/include/storage/buf_internals.h b/src/include/storage/buf_internals.h index ff99f6b..ab04bd9 100644 --- a/src/include/storage/buf_internals.h +++ b/src/include/storage/buf_internals.h @@ -317,6 +317,7 @@ extern void StrategyNotifyBgWriter(int bgwprocno); extern Size StrategyShmemSize(void); extern void StrategyInitialize(bool init); +extern bool have_free_buffer(void); /* buf_table.c */ extern Size BufTableShmemSize(int size); diff --git a/src/tools/pgindent/typedefs.list b/src/tools/pgindent/typedefs.list index 15c72f5..ad6fb9d 100644 --- a/src/tools/pgindent/typedefs.list +++ b/src/tools/pgindent/typedefs.list @@ -133,6 +133,8 @@ AttrDefault AttrNumber AttributeOpts AuthRequest +AutoPrewarmSharedState +AutoPrewarmTask AutoVacOpts AutoVacuumShmemStruct AuxProcType @@ -206,10 +208,12 @@ BitmapOr BitmapOrPath BitmapOrState Bitmapset +BlkType BlobInfo Block BlockId BlockIdData +BlockInfoRecord BlockNumber BlockSampler BlockSamplerData