Movatterモバイル変換

[0]ホーム
URL:

Skip to content

Navigation Menu

Sign in
Appearance settings

Search code, repositories, users, issues, pull requests...

Provide feedback

We read every piece of feedback, and take your input very seriously.

Saved searches

Use saved searches to filter your results more quickly

 Sign up
Appearance settings

Commit8c37e44

Browse files
committed
Allocate freechunks bitmap as part of SlabContext
The bitmap used by SlabCheck to cross-check free chunks in a block usedto be allocated for each SlabCheck call, and was never freed. The memoryleak could be fixed by simply adding a pfree call, but it's actually abad idea to do any allocations in SlabCheck at all as it assumes thestate of the memory management as a whole is sane.So instead we allocate the bitmap as part of SlabContext, which meanswe don't need to do any allocations in SlabCheck and the bitmap goesaway together with the SlabContext.Backpatch to 10, where the Slab context was introduced.Author: Tomas VondraReported-by: Andres FreundReviewed-by: Tom LaneBackpatch-through: 10Discussion:https://www.postgresql.org/message-id/20200116044119.g45f7pmgz4jmodxj%40alap3.anarazel.de
1 parent5ec7bd8 commit8c37e44

File tree

1 file changed

+21
-7
lines changed

1 file changed

+21
-7
lines changed

‎src/backend/utils/mmgr/slab.c

Lines changed: 21 additions & 7 deletions
Original file line numberDiff line numberDiff line change
@@ -71,6 +71,9 @@ typedef struct SlabContext
7171
intchunksPerBlock;/* number of chunks per block */
7272
intminFreeChunks;/* min number of free chunks in any block */
7373
intnblocks;/* number of blocks allocated */
74+
#ifdefMEMORY_CONTEXT_CHECKING
75+
bool*freechunks;/* bitmap of free chunks in a block */
76+
#endif
7477
/* blocks with free space, grouped by number of free chunks: */
7578
dlist_headfreelist[FLEXIBLE_ARRAY_MEMBER];
7679
}SlabContext;
@@ -230,6 +233,15 @@ SlabContextCreate(MemoryContext parent,
230233
/* Size of the memory context header */
231234
headerSize= offsetof(SlabContext,freelist)+freelistSize;
232235

236+
#ifdefMEMORY_CONTEXT_CHECKING
237+
/*
238+
* With memory checking, we need to allocate extra space for the bitmap
239+
* of free chunks. The bitmap is an array of bools, so we don't need to
240+
* worry about alignment.
241+
*/
242+
headerSize+=chunksPerBlock*sizeof(bool);
243+
#endif
244+
233245
slab= (SlabContext*)malloc(headerSize);
234246
if (slab==NULL)
235247
{
@@ -259,6 +271,12 @@ SlabContextCreate(MemoryContext parent,
259271
for (i=0;i< (slab->chunksPerBlock+1);i++)
260272
dlist_init(&slab->freelist[i]);
261273

274+
#ifdefMEMORY_CONTEXT_CHECKING
275+
/* set the freechunks pointer right after the freelists array */
276+
slab->freechunks
277+
= (bool*)slab+ offsetof(SlabContext,freelist)+freelistSize;
278+
#endif
279+
262280
/* Finally, do the type-independent part of context creation */
263281
MemoryContextCreate((MemoryContext)slab,
264282
T_SlabContext,
@@ -694,14 +712,10 @@ SlabCheck(MemoryContext context)
694712
inti;
695713
SlabContext*slab=castNode(SlabContext,context);
696714
constchar*name=slab->header.name;
697-
char*freechunks;
698715

699716
Assert(slab);
700717
Assert(slab->chunksPerBlock>0);
701718

702-
/* bitmap of free chunks on a block */
703-
freechunks=palloc(slab->chunksPerBlock*sizeof(bool));
704-
705719
/* walk all the freelists */
706720
for (i=0;i <=slab->chunksPerBlock;i++)
707721
{
@@ -724,7 +738,7 @@ SlabCheck(MemoryContext context)
724738
name,block->nfree,block,i);
725739

726740
/* reset the bitmap of free chunks for this block */
727-
memset(freechunks,0, (slab->chunksPerBlock*sizeof(bool)));
741+
memset(slab->freechunks,0, (slab->chunksPerBlock*sizeof(bool)));
728742
idx=block->firstFreeChunk;
729743

730744
/*
@@ -741,7 +755,7 @@ SlabCheck(MemoryContext context)
741755

742756
/* count the chunk as free, add it to the bitmap */
743757
nfree++;
744-
freechunks[idx]= true;
758+
slab->freechunks[idx]= true;
745759

746760
/* read index of the next free chunk */
747761
chunk=SlabBlockGetChunk(slab,block,idx);
@@ -752,7 +766,7 @@ SlabCheck(MemoryContext context)
752766
for (j=0;j<slab->chunksPerBlock;j++)
753767
{
754768
/* non-zero bit in the bitmap means chunk the chunk is used */
755-
if (!freechunks[j])
769+
if (!slab->freechunks[j])
756770
{
757771
SlabChunk*chunk=SlabBlockGetChunk(slab,block,j);
758772

0 commit comments

Comments
 (0)
[8]ページ先頭
©2009-2025 Movatter.jp