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2019年3月18日 21:54:24 +0000 (17:54 -0400)

2019年3月18日 21:54:41 +0000 (17:54 -0400)

Commit f2dec34e1 changed things so that printtup's output stringinfo
buffer was allocated outside the per-row temporary context, not inside
it. This creates a need to free that buffer explicitly when the temp
context is freed, but that was overlooked. In most cases, this is all
happening inside a portal or executor context that will go away shortly
anyhow, but that's not always true. Notably, the stringinfo ends up
getting leaked when JDBC uses row-at-a-time fetches. For a query
that returns wide rows, that adds up after awhile.

Per bug #15700 from Matthias Otterbach. Back-patch to v11 where the
faulty code was added.

Discussion: https://postgr.es/m/15700-8c408321a87d56bb@postgresql.org

src/backend/access/common/printtup.c patch | blob | blame | history

diff --git a/src/backend/access/common/printtup.c b/src/backend/access/common/printtup.c

index e4ee5c9d3450cf3afe24a8c71812f24ec6f5a4fb..44add482d3ec1ec6b9ab924217f1146db30b7426 100644 (file)

--- a/src/backend/access/common/printtup.c

+++ b/src/backend/access/common/printtup.c

@@ -61,12 +61,12 @@ typedef struct

typedef struct

{

DestReceiver pub; /* publicly-known function pointers */

- StringInfoData buf; /* output buffer */

Portal portal; /* the Portal we are printing from */

bool sendDescrip; /* send RowDescription at startup? */

TupleDesc attrinfo; /* The attr info we are set up for */

int nattrs;

PrinttupAttrInfo *myinfo; /* Cached info about each attr */

+ StringInfoData buf; /* output buffer (*not* in tmpcontext) */

MemoryContext tmpcontext; /* Memory context for per-row workspace */

} DR_printtup;

@@ -94,6 +94,7 @@ printtup_create_DR(CommandDest dest)

self->attrinfo = NULL;

self->nattrs = 0;

self->myinfo = NULL;

+ self->buf.data = NULL;

self->tmpcontext = NULL;

return (DestReceiver *) self;

@@ -132,7 +133,10 @@ printtup_startup(DestReceiver *self, int operation, TupleDesc typeinfo)

DR_printtup *myState = (DR_printtup *) self;

Portal portal = myState->portal;

- /* create buffer to be used for all messages */

+ /*

+ * Create I/O buffer to be used for all messages. This cannot be inside

+ * tmpcontext, since we want to re-use it across rows.

+ */

initStringInfo(&myState->buf);

@@ -544,6 +548,10 @@ printtup_shutdown(DestReceiver *self)

myState->attrinfo = NULL;

+ if (myState->buf.data)

+ pfree(myState->buf.data);

+ myState->buf.data = NULL;

if (myState->tmpcontext)

MemoryContextDelete(myState->tmpcontext);

myState->tmpcontext = NULL;

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