From: Heikki Linnakangas Date: Fri, 4 Apr 2014 10:12:38 +0000 (+0300) Subject: Avoid allocations in critical sections. X-Git-Tag: REL8_4_22~51 X-Git-Url: http://git.ipfire.org/?a=commitdiff_plain;h=129b8adbc8cd7acd435904890a12888ead7a5ba4;p=thirdparty%2Fpostgresql.git Avoid allocations in critical sections. If a palloc in a critical section fails, it becomes a PANIC. --- diff --git a/src/backend/access/nbtree/nbtinsert.c b/src/backend/access/nbtree/nbtinsert.c index f866143e59b..e8cdadfebd5 100644 --- a/src/backend/access/nbtree/nbtinsert.c +++ b/src/backend/access/nbtree/nbtinsert.c @@ -1726,8 +1726,10 @@ _bt_newroot(Relation rel, Buffer lbuf, Buffer rbuf) BTPageOpaque rootopaque; ItemId itemid; IndexTuple item; - Size itemsz; - IndexTuple new_item; + IndexTuple left_item; + Size left_item_sz; + IndexTuple right_item; + Size right_item_sz; Buffer metabuf; Page metapg; BTMetaPageData *metad; @@ -1746,6 +1748,26 @@ _bt_newroot(Relation rel, Buffer lbuf, Buffer rbuf) metapg = BufferGetPage(metabuf); metad = BTPageGetMeta(metapg); + /* + * Create downlink item for left page (old root). Since this will be the + * first item in a non-leaf page, it implicitly has minus-infinity key + * value, so we need not store any actual key in it. + */ + left_item_sz = sizeof(IndexTupleData); + left_item = (IndexTuple) palloc(left_item_sz); + left_item->t_info = left_item_sz; + ItemPointerSet(&(left_item->t_tid), lbkno, P_HIKEY); + + /* + * Create downlink item for right page. The key for it is obtained from + * the "high key" position in the left page. + */ + itemid = PageGetItemId(lpage, P_HIKEY); + right_item_sz = ItemIdGetLength(itemid); + item = (IndexTuple) PageGetItem(lpage, itemid); + right_item = CopyIndexTuple(item); + ItemPointerSet(&(right_item->t_tid), rbkno, P_HIKEY); + /* NO EREPORT(ERROR) from here till newroot op is logged */ START_CRIT_SECTION(); @@ -1763,16 +1785,6 @@ _bt_newroot(Relation rel, Buffer lbuf, Buffer rbuf) metad->btm_fastroot = rootblknum; metad->btm_fastlevel = rootopaque->btpo.level; - /* - * Create downlink item for left page (old root). Since this will be the - * first item in a non-leaf page, it implicitly has minus-infinity key - * value, so we need not store any actual key in it. - */ - itemsz = sizeof(IndexTupleData); - new_item = (IndexTuple) palloc(itemsz); - new_item->t_info = itemsz; - ItemPointerSet(&(new_item->t_tid), lbkno, P_HIKEY); - /* * Insert the left page pointer into the new root page. The root page is * the rightmost page on its level so there is no "high key" in it; the @@ -1781,32 +1793,20 @@ _bt_newroot(Relation rel, Buffer lbuf, Buffer rbuf) * Note: we *must* insert the two items in item-number order, for the * benefit of _bt_restore_page(). */ - if (PageAddItem(rootpage, (Item) new_item, itemsz, P_HIKEY, + if (PageAddItem(rootpage, (Item) left_item, left_item_sz, P_HIKEY, false, false) == InvalidOffsetNumber) elog(PANIC, "failed to add leftkey to new root page" " while splitting block %u of index \"%s\"", BufferGetBlockNumber(lbuf), RelationGetRelationName(rel)); - pfree(new_item); - - /* - * Create downlink item for right page. The key for it is obtained from - * the "high key" position in the left page. - */ - itemid = PageGetItemId(lpage, P_HIKEY); - itemsz = ItemIdGetLength(itemid); - item = (IndexTuple) PageGetItem(lpage, itemid); - new_item = CopyIndexTuple(item); - ItemPointerSet(&(new_item->t_tid), rbkno, P_HIKEY); /* * insert the right page pointer into the new root page. */ - if (PageAddItem(rootpage, (Item) new_item, itemsz, P_FIRSTKEY, + if (PageAddItem(rootpage, (Item) right_item, right_item_sz, P_FIRSTKEY, false, false) == InvalidOffsetNumber) elog(PANIC, "failed to add rightkey to new root page" " while splitting block %u of index \"%s\"", BufferGetBlockNumber(lbuf), RelationGetRelationName(rel)); - pfree(new_item); MarkBufferDirty(rootbuf); MarkBufferDirty(metabuf); @@ -1854,6 +1854,9 @@ _bt_newroot(Relation rel, Buffer lbuf, Buffer rbuf) /* done with metapage */ _bt_relbuf(rel, metabuf); + pfree(left_item); + pfree(right_item); + return rootbuf; } diff --git a/src/backend/access/transam/xlog.c b/src/backend/access/transam/xlog.c index b8ca6857afb..35904f4b2c2 100644 --- a/src/backend/access/transam/xlog.c +++ b/src/backend/access/transam/xlog.c @@ -2167,6 +2167,7 @@ XLogFileInit(uint32 log, uint32 seg, { char path[MAXPGPATH]; char tmppath[MAXPGPATH]; + char zbuffer_raw[BLCKSZ + MAXIMUM_ALIGNOF]; char *zbuffer; uint32 installed_log; uint32 installed_seg; @@ -2224,11 +2225,11 @@ XLogFileInit(uint32 log, uint32 seg, * fdatasync(2) or O_DSYNC will be sufficient to sync future writes to the * log file. * - * Note: palloc zbuffer, instead of just using a local char array, to - * ensure it is reasonably well-aligned; this may save a few cycles - * transferring data to the kernel. + * Note: ensure the buffer is reasonably well-aligned; this may save a few + * cycles transferring data to the kernel. */ - zbuffer = (char *) palloc0(XLOG_BLCKSZ); + zbuffer = (char *) MAXALIGN(zbuffer_raw); + memset(zbuffer, 0, BLCKSZ); for (nbytes = 0; nbytes < XLogSegSize; nbytes += XLOG_BLCKSZ) { errno = 0; @@ -2248,7 +2249,6 @@ XLogFileInit(uint32 log, uint32 seg, errmsg("could not write to file \"%s\": %m", tmppath))); } } - pfree(zbuffer); if (pg_fsync(fd) != 0) ereport(ERROR, diff --git a/src/backend/storage/page/bufpage.c b/src/backend/storage/page/bufpage.c index b59602ec128..70784cf35a7 100644 --- a/src/backend/storage/page/bufpage.c +++ b/src/backend/storage/page/bufpage.c @@ -15,6 +15,7 @@ #include "postgres.h" #include "access/htup.h" +#include "access/itup.h" #include "storage/bufpage.h" @@ -363,8 +364,6 @@ PageRepairFragmentation(Page page) Offset pd_lower = ((PageHeader) page)->pd_lower; Offset pd_upper = ((PageHeader) page)->pd_upper; Offset pd_special = ((PageHeader) page)->pd_special; - itemIdSort itemidbase, - itemidptr; ItemId lp; int nline, nstorage, @@ -414,10 +413,11 @@ PageRepairFragmentation(Page page) ((PageHeader) page)->pd_upper = pd_special; } else - { /* nstorage != 0 */ + { /* Need to compact the page the hard way */ - itemidbase = (itemIdSort) palloc(sizeof(itemIdSortData) * nstorage); - itemidptr = itemidbase; + itemIdSortData itemidbase[MaxHeapTuplesPerPage]; + itemIdSort itemidptr = itemidbase; + totallen = 0; for (i = 0; i < nline; i++) { @@ -462,8 +462,6 @@ PageRepairFragmentation(Page page) } ((PageHeader) page)->pd_upper = upper; - - pfree(itemidbase); } /* Set hint bit for PageAddItem */ @@ -712,8 +710,8 @@ PageIndexMultiDelete(Page page, OffsetNumber *itemnos, int nitems) Offset pd_lower = phdr->pd_lower; Offset pd_upper = phdr->pd_upper; Offset pd_special = phdr->pd_special; - itemIdSort itemidbase, - itemidptr; + itemIdSortData itemidbase[MaxIndexTuplesPerPage]; + itemIdSort itemidptr; ItemId lp; int nline, nused; @@ -725,6 +723,8 @@ PageIndexMultiDelete(Page page, OffsetNumber *itemnos, int nitems) int nextitm; OffsetNumber offnum; + Assert(nitems < MaxIndexTuplesPerPage); + /* * If there aren't very many items to delete, then retail * PageIndexTupleDelete is the best way. Delete the items in reverse @@ -759,7 +759,6 @@ PageIndexMultiDelete(Page page, OffsetNumber *itemnos, int nitems) * still validity-checking. */ nline = PageGetMaxOffsetNumber(page); - itemidbase = (itemIdSort) palloc(sizeof(itemIdSortData) * nline); itemidptr = itemidbase; totallen = 0; nused = 0; @@ -825,6 +824,4 @@ PageIndexMultiDelete(Page page, OffsetNumber *itemnos, int nitems) phdr->pd_lower = SizeOfPageHeaderData + nused * sizeof(ItemIdData); phdr->pd_upper = upper; - - pfree(itemidbase); }