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Avoid allocations in critical sections. 

If a palloc in a critical section fails, it becomes a PANIC.
This commit is contained in:
Heikki Linnakangas 2014-04-04 13:12:38 +03:00
parent c7b3539599
commit 877b088785
4 changed files with 49 additions and 57 deletions
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55
src/backend/access/nbtree/nbtinsert.c
View File

@ -1995,8 +1995,10 @@ _bt_newroot(Relation rel, Buffer lbuf, Buffer rbuf)
BTPageOpaque lopaque;
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;
@ -2016,6 +2018,26 @@ _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();
@ -2033,16 +2055,6 @@ _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
@ -2051,32 +2063,20 @@ _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);
/* Clear the incomplete-split flag in the left child */
Assert(P_INCOMPLETE_SPLIT(lopaque));
@ -2129,6 +2129,9 @@ _bt_newroot(Relation rel, Buffer lbuf, Buffer rbuf)
/* done with metapage */
_bt_relbuf(rel, metabuf);
pfree(left_item);
pfree(right_item);
return rootbuf;
}

8
src/backend/access/spgist/spgdoinsert.c
View File

@ -122,7 +122,8 @@ cmpOffsetNumbers(const void *a, const void *b)
*
* NB: this is used during WAL replay, so beware of trying to make it too
* smart. In particular, it shouldn't use "state" except for calling
* spgFormDeadTuple().
* spgFormDeadTuple(). This is also used in a critical section, so no
* pallocs either!
*/
void
spgPageIndexMultiDelete(SpGistState *state, Page page,
@ -131,7 +132,7 @@ spgPageIndexMultiDelete(SpGistState *state, Page page,
BlockNumber blkno, OffsetNumber offnum)
{
OffsetNumber firstItem;
OffsetNumber *sortednos;
OffsetNumber sortednos[MaxIndexTuplesPerPage];
SpGistDeadTuple tuple = NULL;
int i;
@ -145,7 +146,6 @@ spgPageIndexMultiDelete(SpGistState *state, Page page,
* replacement tuples.) However, we must not scribble on the caller's
* array, so we have to make a copy.
*/
sortednos = (OffsetNumber *) palloc(sizeof(OffsetNumber) * nitems);
memcpy(sortednos, itemnos, sizeof(OffsetNumber) * nitems);
if (nitems > 1)
qsort(sortednos, nitems, sizeof(OffsetNumber), cmpOffsetNumbers);
@ -173,8 +173,6 @@ spgPageIndexMultiDelete(SpGistState *state, Page page,
else if (tupstate == SPGIST_PLACEHOLDER)
SpGistPageGetOpaque(page)->nPlaceholder++;
}
pfree(sortednos);
}
/*

22
src/backend/access/transam/xlog.c
View File

@ -859,9 +859,8 @@ XLogInsert(RmgrId rmid, uint8 info, XLogRecData *rdata)
if (rechdr == NULL)
{
rechdr = malloc(SizeOfXLogRecord);
if (rechdr == NULL)
elog(ERROR, "out of memory");
static char rechdrbuf[SizeOfXLogRecord + MAXIMUM_ALIGNOF];
rechdr = (XLogRecord *) MAXALIGN(&rechdrbuf);
MemSet(rechdr, 0, SizeOfXLogRecord);
}
@ -3080,6 +3079,7 @@ XLogFileInit(XLogSegNo logsegno, bool *use_existent, bool use_lock)
{
char path[MAXPGPATH];
char tmppath[MAXPGPATH];
char zbuffer_raw[BLCKSZ + MAXIMUM_ALIGNOF];
char *zbuffer;
XLogSegNo installed_segno;
int max_advance;
@ -3118,16 +3118,6 @@ XLogFileInit(XLogSegNo logsegno, bool *use_existent, bool use_lock)
unlink(tmppath);
/*
* Allocate a buffer full of zeros. This is done before opening the file
* so that we don't leak the file descriptor if palloc fails.
*
* 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.
*/
zbuffer = (char *) palloc0(XLOG_BLCKSZ);
/* do not use get_sync_bit() here --- want to fsync only at end of fill */
fd = BasicOpenFile(tmppath, O_RDWR | O_CREAT | O_EXCL | PG_BINARY,
S_IRUSR | S_IWUSR);
@ -3144,7 +3134,12 @@ XLogFileInit(XLogSegNo logsegno, bool *use_existent, bool use_lock)
* fsync below) that all the indirect blocks are down on disk. Therefore,
* fdatasync(2) or O_DSYNC will be sufficient to sync future writes to the
* log file.
*
* Note: ensure the buffer is reasonably well-aligned; this may save a few
* cycles transferring data to the kernel.
*/
zbuffer = (char *) MAXALIGN(zbuffer_raw);
memset(zbuffer, 0, BLCKSZ);
for (nbytes = 0; nbytes < XLogSegSize; nbytes += XLOG_BLCKSZ)
{
errno = 0;
@ -3167,7 +3162,6 @@ XLogFileInit(XLogSegNo logsegno, bool *use_existent, bool use_lock)
errmsg("could not write to file \"%s\": %m", tmppath)));
}
}
pfree(zbuffer);
if (pg_fsync(fd) != 0)
{

21
src/backend/storage/page/bufpage.c
View File

@ -15,6 +15,7 @@
#include "postgres.h"
#include "access/htup_details.h"
#include "access/itup.h"
#include "access/xlog.h"
#include "storage/checksum.h"
#include "utils/memdebug.h"
@ -433,8 +434,6 @@ 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,
@ -484,10 +483,11 @@ 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++)
{
@ -532,8 +532,6 @@ PageRepairFragmentation(Page page)
}
((PageHeader) page)->pd_upper = upper;
pfree(itemidbase);
}
/* Set hint bit for PageAddItem */
@ -782,8 +780,8 @@ 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;
@ -795,6 +793,8 @@ 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
@ -829,7 +829,6 @@ 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;
@ -895,8 +894,6 @@ PageIndexMultiDelete(Page page, OffsetNumber *itemnos, int nitems)
phdr->pd_lower = SizeOfPageHeaderData + nused * sizeof(ItemIdData);
phdr->pd_upper = upper;
pfree(itemidbase);
}