From d9c7911e1a5f354b7c34b7f53a52e0a690e7ebc9 Mon Sep 17 00:00:00 2001 From: Melanie Plageman Date: Fri, 4 Apr 2025 15:25:45 -0400 Subject: [PATCH] Use streaming read I/O in autoprewarm Make a read stream for each valid fork of each valid relation represented in the autoprewarm dump file and prewarm those blocks through the read stream API instead of by directly invoking ReadBuffer(). Co-authored-by: Nazir Bilal Yavuz Co-authored-by: Melanie Plageman Reviewed-by: Heikki Linnakangas Reviewed-by: Daniel Gustafsson Reviewed-by: Andrey M. Borodin (earlier versions) Reviewed-by: Kirill Reshke (earlier versions) Reviewed-by: Matheus Alcantara (earlier versions) Discussion: https://postgr.es/m/flat/CAN55FZ3n8Gd%2BhajbL%3D5UkGzu_aHGRqnn%2BxktXq2fuds%3D1AOR6Q%40mail.gmail.com --- contrib/pg_prewarm/autoprewarm.c | 126 +++++++++++++++++++++++++------ src/tools/pgindent/typedefs.list | 1 + 2 files changed, 104 insertions(+), 23 deletions(-) diff --git a/contrib/pg_prewarm/autoprewarm.c b/contrib/pg_prewarm/autoprewarm.c index 761f6a77926..bde0523f082 100644 --- a/contrib/pg_prewarm/autoprewarm.c +++ b/contrib/pg_prewarm/autoprewarm.c @@ -41,6 +41,7 @@ #include "storage/latch.h" #include "storage/lwlock.h" #include "storage/procsignal.h" +#include "storage/read_stream.h" #include "storage/smgr.h" #include "tcop/tcopprot.h" #include "utils/guc.h" @@ -75,6 +76,28 @@ typedef struct AutoPrewarmSharedState int prewarmed_blocks; } AutoPrewarmSharedState; +/* + * Private data passed through the read stream API for our use in the + * callback. + */ +typedef struct AutoPrewarmReadStreamData +{ + /* The array of records containing the blocks we should prewarm. */ + BlockInfoRecord *block_info; + + /* + * pos is the read stream callback's index into block_info. Because the + * read stream may read ahead, pos is likely to be ahead of the index in + * the main loop in autoprewarm_database_main(). + */ + int pos; + Oid tablespace; + RelFileNumber filenumber; + ForkNumber forknum; + BlockNumber nblocks; +} AutoPrewarmReadStreamData; + + PGDLLEXPORT void autoprewarm_main(Datum main_arg); PGDLLEXPORT void autoprewarm_database_main(Datum main_arg); @@ -422,6 +445,54 @@ apw_load_buffers(void) apw_state->prewarmed_blocks, num_elements))); } +/* + * Return the next block number of a specific relation and fork to read + * according to the array of BlockInfoRecord. + */ +static BlockNumber +apw_read_stream_next_block(ReadStream *stream, + void *callback_private_data, + void *per_buffer_data) +{ + AutoPrewarmReadStreamData *p = callback_private_data; + + CHECK_FOR_INTERRUPTS(); + + while (p->pos < apw_state->prewarm_stop_idx) + { + BlockInfoRecord blk = p->block_info[p->pos]; + + if (!have_free_buffer()) + { + p->pos = apw_state->prewarm_stop_idx; + return InvalidBlockNumber; + } + + if (blk.tablespace != p->tablespace) + return InvalidBlockNumber; + + if (blk.filenumber != p->filenumber) + return InvalidBlockNumber; + + if (blk.forknum != p->forknum) + return InvalidBlockNumber; + + p->pos++; + + /* + * Check whether blocknum is valid and within fork file size. + * Fast-forward through any invalid blocks. We want p->pos to reflect + * the location of the next relation or fork before ending the stream. + */ + if (blk.blocknum >= p->nblocks) + continue; + + return blk.blocknum; + } + + return InvalidBlockNumber; +} + /* * Prewarm all blocks for one database (and possibly also global objects, if * those got grouped with this database). @@ -462,8 +533,6 @@ autoprewarm_database_main(Datum main_arg) Oid reloid; Relation rel; - CHECK_FOR_INTERRUPTS(); - /* * All blocks between prewarm_start_idx and prewarm_stop_idx should * belong either to global objects or the same database. @@ -510,6 +579,8 @@ autoprewarm_database_main(Datum main_arg) { ForkNumber forknum = blk.forknum; BlockNumber nblocks; + struct AutoPrewarmReadStreamData p; + ReadStream *stream; Buffer buf; /* @@ -540,32 +611,41 @@ autoprewarm_database_main(Datum main_arg) nblocks = RelationGetNumberOfBlocksInFork(rel, blk.forknum); - /* Prewarm buffers. */ - while (i < apw_state->prewarm_stop_idx && - blk.tablespace == tablespace && - blk.filenumber == filenumber && - blk.forknum == forknum && - have_free_buffer()) + p = (struct AutoPrewarmReadStreamData) { - CHECK_FOR_INTERRUPTS(); - - /* Check whether blocknum is valid and within fork file size. */ - if (blk.blocknum >= nblocks) - { - blk = block_info[++i]; - continue; - } - - buf = ReadBufferExtended(rel, blk.forknum, blk.blocknum, RBM_NORMAL, - NULL); - - blk = block_info[++i]; - if (!BufferIsValid(buf)) - break; + .block_info = block_info, + .pos = i, + .tablespace = tablespace, + .filenumber = filenumber, + .forknum = forknum, + .nblocks = nblocks, + }; + + stream = read_stream_begin_relation(READ_STREAM_DEFAULT | + READ_STREAM_USE_BATCHING, + NULL, + rel, + p.forknum, + apw_read_stream_next_block, + &p, + 0); + /* + * Loop until we've prewarmed all the blocks from this fork. The + * read stream callback will check that we still have free buffers + * before requesting each block from the read stream API. + */ + while ((buf = read_stream_next_buffer(stream, NULL)) != InvalidBuffer) + { apw_state->prewarmed_blocks++; ReleaseBuffer(buf); } + + read_stream_end(stream); + + /* Advance i past all the blocks just prewarmed. */ + i = p.pos; + blk = block_info[i]; } relation_close(rel, AccessShareLock); diff --git a/src/tools/pgindent/typedefs.list b/src/tools/pgindent/typedefs.list index 229fbff47ae..b69b3b1520c 100644 --- a/src/tools/pgindent/typedefs.list +++ b/src/tools/pgindent/typedefs.list @@ -175,6 +175,7 @@ AttributeOpts AuthRequest AuthToken AutoPrewarmSharedState +AutoPrewarmReadStreamData AutoVacOpts AutoVacuumShmemStruct AutoVacuumWorkItem -- 2.30.2