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Avoid deep recursion when assigning XIDs to multiple levels of subxacts. 

Backpatch to 8.0.

Andres Freund, with cleanup and adjustment for older branches by me.
This commit is contained in:
Robert Haas 2010-07-23 00:43:52 +00:00
parent b239670173
commit b26ed3584a
1 changed files with 29 additions and 2 deletions
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31
src/backend/access/transam/xact.c
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@ -10,7 +10,7 @@
*
*
* IDENTIFICATION
* $PostgreSQL: pgsql/src/backend/access/transam/xact.c,v 1.195.4.6 2010/01/24 21:50:06 tgl Exp $
* $PostgreSQL: pgsql/src/backend/access/transam/xact.c,v 1.195.4.7 2010/07/23 00:43:52 rhaas Exp $
*
*-------------------------------------------------------------------------
*/
@ -339,8 +339,35 @@ AssignSubTransactionId(TransactionState s)
Assert(s->parent != NULL);
Assert(s->state == TRANS_INPROGRESS);
/*
* Ensure parent(s) have XIDs, so that a child always has an XID later
* than its parent. Musn't recurse here, or we might get a stack overflow
* if we're at the bottom of a huge stack of subtransactions none of which
* have XIDs yet.
*/
if (!TransactionIdIsValid(s->parent->transactionId))
AssignSubTransactionId(s->parent);
{
TransactionState p = s->parent;
TransactionState *parents;
size_t parentOffset = 0;
parents = palloc(sizeof(TransactionState) * s->nestingLevel);
while (p != NULL && !TransactionIdIsValid(p->transactionId))
{
parents[parentOffset++] = p;
p = p->parent;
}
/*
* This is technically a recursive call, but the recursion will
* never be more than one layer deep.
*/
while (parentOffset != 0)
AssignSubTransactionId(parents[--parentOffset]);
pfree(parents);
}
/*
* Generate a new Xid and record it in PG_PROC and pg_subtrans.