postgres.git / summary / log / commit / refs

commit    adf27de8eabbf43b049d1a1bb72780e53e8ea863
Author:   Tom Lane <tgl@sss.pgh.pa.us>
Date:     Mon Mar 18 21:54:24 2019 +0000
First released in: 12.0, 11.3

    Fix memory leak in printtup.c.
    
    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 | 12 ++++++++++--
 1 file changed, 10 insertions(+), 2 deletions(-)

diff --git a/src/backend/access/common/printtup.c b/src/backend/access/common/printtup.c
index a1d44157044..f42d1c7e78f 100644
--- 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;


[parent: fc8b39a46eb7]