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Commitaf7004e

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Avoid allocations in critical sections.
If a palloc in a critical section fails, it becomes a PANIC.
1 parent0de9963 commitaf7004e

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3 files changed

+43
-43
lines changed

3 files changed

+43
-43
lines changed

‎src/backend/access/nbtree/nbtinsert.c

Lines changed: 29 additions & 26 deletions
Original file line numberDiff line numberDiff line change
@@ -1828,8 +1828,10 @@ _bt_newroot(Relation rel, Buffer lbuf, Buffer rbuf)
18281828
BTPageOpaquerootopaque;
18291829
ItemIditemid;
18301830
IndexTupleitem;
1831-
Sizeitemsz;
1832-
IndexTuplenew_item;
1831+
IndexTupleleft_item;
1832+
Sizeleft_item_sz;
1833+
IndexTupleright_item;
1834+
Sizeright_item_sz;
18331835
Buffermetabuf;
18341836
Pagemetapg;
18351837
BTMetaPageData*metad;
@@ -1848,6 +1850,26 @@ _bt_newroot(Relation rel, Buffer lbuf, Buffer rbuf)
18481850
metapg=BufferGetPage(metabuf);
18491851
metad=BTPageGetMeta(metapg);
18501852

1853+
/*
1854+
* Create downlink item for left page (old root). Since this will be the
1855+
* first item in a non-leaf page, it implicitly has minus-infinity key
1856+
* value, so we need not store any actual key in it.
1857+
*/
1858+
left_item_sz=sizeof(IndexTupleData);
1859+
left_item= (IndexTuple)palloc(left_item_sz);
1860+
left_item->t_info=left_item_sz;
1861+
ItemPointerSet(&(left_item->t_tid),lbkno,P_HIKEY);
1862+
1863+
/*
1864+
* Create downlink item for right page. The key for it is obtained from
1865+
* the "high key" position in the left page.
1866+
*/
1867+
itemid=PageGetItemId(lpage,P_HIKEY);
1868+
right_item_sz=ItemIdGetLength(itemid);
1869+
item= (IndexTuple)PageGetItem(lpage,itemid);
1870+
right_item=CopyIndexTuple(item);
1871+
ItemPointerSet(&(right_item->t_tid),rbkno,P_HIKEY);
1872+
18511873
/* NO EREPORT(ERROR) from here till newroot op is logged */
18521874
START_CRIT_SECTION();
18531875

@@ -1865,16 +1887,6 @@ _bt_newroot(Relation rel, Buffer lbuf, Buffer rbuf)
18651887
metad->btm_fastroot=rootblknum;
18661888
metad->btm_fastlevel=rootopaque->btpo.level;
18671889

1868-
/*
1869-
* Create downlink item for left page (old root). Since this will be the
1870-
* first item in a non-leaf page, it implicitly has minus-infinity key
1871-
* value, so we need not store any actual key in it.
1872-
*/
1873-
itemsz=sizeof(IndexTupleData);
1874-
new_item= (IndexTuple)palloc(itemsz);
1875-
new_item->t_info=itemsz;
1876-
ItemPointerSet(&(new_item->t_tid),lbkno,P_HIKEY);
1877-
18781890
/*
18791891
* Insert the left page pointer into the new root page. The root page is
18801892
* the rightmost page on its level so there is no "high key" in it; the
@@ -1883,32 +1895,20 @@ _bt_newroot(Relation rel, Buffer lbuf, Buffer rbuf)
18831895
* Note: we *must* insert the two items in item-number order, for the
18841896
* benefit of _bt_restore_page().
18851897
*/
1886-
if (PageAddItem(rootpage, (Item)new_item,itemsz,P_HIKEY,
1898+
if (PageAddItem(rootpage, (Item)left_item,left_item_sz,P_HIKEY,
18871899
false, false)==InvalidOffsetNumber)
18881900
elog(PANIC,"failed to add leftkey to new root page"
18891901
" while splitting block %u of index \"%s\"",
18901902
BufferGetBlockNumber(lbuf),RelationGetRelationName(rel));
1891-
pfree(new_item);
1892-
1893-
/*
1894-
* Create downlink item for right page. The key for it is obtained from
1895-
* the "high key" position in the left page.
1896-
*/
1897-
itemid=PageGetItemId(lpage,P_HIKEY);
1898-
itemsz=ItemIdGetLength(itemid);
1899-
item= (IndexTuple)PageGetItem(lpage,itemid);
1900-
new_item=CopyIndexTuple(item);
1901-
ItemPointerSet(&(new_item->t_tid),rbkno,P_HIKEY);
19021903

19031904
/*
19041905
* insert the right page pointer into the new root page.
19051906
*/
1906-
if (PageAddItem(rootpage, (Item)new_item,itemsz,P_FIRSTKEY,
1907+
if (PageAddItem(rootpage, (Item)right_item,right_item_sz,P_FIRSTKEY,
19071908
false, false)==InvalidOffsetNumber)
19081909
elog(PANIC,"failed to add rightkey to new root page"
19091910
" while splitting block %u of index \"%s\"",
19101911
BufferGetBlockNumber(lbuf),RelationGetRelationName(rel));
1911-
pfree(new_item);
19121912

19131913
MarkBufferDirty(rootbuf);
19141914
MarkBufferDirty(metabuf);
@@ -1956,6 +1956,9 @@ _bt_newroot(Relation rel, Buffer lbuf, Buffer rbuf)
19561956
/* done with metapage */
19571957
_bt_relbuf(rel,metabuf);
19581958

1959+
pfree(left_item);
1960+
pfree(right_item);
1961+
19591962
returnrootbuf;
19601963
}
19611964

‎src/backend/access/transam/xlog.c

Lines changed: 5 additions & 5 deletions
Original file line numberDiff line numberDiff line change
@@ -2289,6 +2289,7 @@ XLogFileInit(uint32 log, uint32 seg,
22892289
{
22902290
charpath[MAXPGPATH];
22912291
chartmppath[MAXPGPATH];
2292+
charzbuffer_raw[BLCKSZ+MAXIMUM_ALIGNOF];
22922293
char*zbuffer;
22932294
uint32installed_log;
22942295
uint32installed_seg;
@@ -2346,11 +2347,11 @@ XLogFileInit(uint32 log, uint32 seg,
23462347
* fdatasync(2) or O_DSYNC will be sufficient to sync future writes to the
23472348
* log file.
23482349
*
2349-
* Note: palloc zbuffer, instead of just using a local char array, to
2350-
* ensure it is reasonably well-aligned; this may save a few cycles
2351-
* transferring data to the kernel.
2350+
* Note: ensure the buffer is reasonably well-aligned; this may save a few
2351+
* cycles transferring data to the kernel.
23522352
*/
2353-
zbuffer= (char*)palloc0(XLOG_BLCKSZ);
2353+
zbuffer= (char*)MAXALIGN(zbuffer_raw);
2354+
memset(zbuffer,0,BLCKSZ);
23542355
for (nbytes=0;nbytes<XLogSegSize;nbytes+=XLOG_BLCKSZ)
23552356
{
23562357
errno=0;
@@ -2370,7 +2371,6 @@ XLogFileInit(uint32 log, uint32 seg,
23702371
errmsg("could not write to file \"%s\": %m",tmppath)));
23712372
}
23722373
}
2373-
pfree(zbuffer);
23742374

23752375
if (pg_fsync(fd)!=0)
23762376
ereport(ERROR,

‎src/backend/storage/page/bufpage.c

Lines changed: 9 additions & 12 deletions
Original file line numberDiff line numberDiff line change
@@ -15,6 +15,7 @@
1515
#include"postgres.h"
1616

1717
#include"access/htup.h"
18+
#include"access/itup.h"
1819
#include"storage/bufpage.h"
1920

2021

@@ -363,8 +364,6 @@ PageRepairFragmentation(Page page)
363364
Offsetpd_lower= ((PageHeader)page)->pd_lower;
364365
Offsetpd_upper= ((PageHeader)page)->pd_upper;
365366
Offsetpd_special= ((PageHeader)page)->pd_special;
366-
itemIdSortitemidbase,
367-
itemidptr;
368367
ItemIdlp;
369368
intnline,
370369
nstorage,
@@ -414,10 +413,11 @@ PageRepairFragmentation(Page page)
414413
((PageHeader)page)->pd_upper=pd_special;
415414
}
416415
else
417-
{/* nstorage != 0 */
416+
{
418417
/* Need to compact the page the hard way */
419-
itemidbase= (itemIdSort)palloc(sizeof(itemIdSortData)*nstorage);
420-
itemidptr=itemidbase;
418+
itemIdSortDataitemidbase[MaxHeapTuplesPerPage];
419+
itemIdSortitemidptr=itemidbase;
420+
421421
totallen=0;
422422
for (i=0;i<nline;i++)
423423
{
@@ -462,8 +462,6 @@ PageRepairFragmentation(Page page)
462462
}
463463

464464
((PageHeader)page)->pd_upper=upper;
465-
466-
pfree(itemidbase);
467465
}
468466

469467
/* Set hint bit for PageAddItem */
@@ -712,8 +710,8 @@ PageIndexMultiDelete(Page page, OffsetNumber *itemnos, int nitems)
712710
Offsetpd_lower=phdr->pd_lower;
713711
Offsetpd_upper=phdr->pd_upper;
714712
Offsetpd_special=phdr->pd_special;
715-
itemIdSortitemidbase,
716-
itemidptr;
713+
itemIdSortDataitemidbase[MaxIndexTuplesPerPage];
714+
itemIdSortitemidptr;
717715
ItemIdlp;
718716
intnline,
719717
nused;
@@ -725,6 +723,8 @@ PageIndexMultiDelete(Page page, OffsetNumber *itemnos, int nitems)
725723
intnextitm;
726724
OffsetNumberoffnum;
727725

726+
Assert(nitems<MaxIndexTuplesPerPage);
727+
728728
/*
729729
* If there aren't very many items to delete, then retail
730730
* PageIndexTupleDelete is the best way. Delete the items in reverse
@@ -759,7 +759,6 @@ PageIndexMultiDelete(Page page, OffsetNumber *itemnos, int nitems)
759759
* still validity-checking.
760760
*/
761761
nline=PageGetMaxOffsetNumber(page);
762-
itemidbase= (itemIdSort)palloc(sizeof(itemIdSortData)*nline);
763762
itemidptr=itemidbase;
764763
totallen=0;
765764
nused=0;
@@ -825,6 +824,4 @@ PageIndexMultiDelete(Page page, OffsetNumber *itemnos, int nitems)
825824

826825
phdr->pd_lower=SizeOfPageHeaderData+nused*sizeof(ItemIdData);
827826
phdr->pd_upper=upper;
828-
829-
pfree(itemidbase);
830827
}

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