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

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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 00:43:00 +00:00
parent bca03b12c1
commit 7be8946c78
1 changed files with 25 additions and 3 deletions
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28
src/backend/access/transam/xact.c
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@ -10,7 +10,7 @@
* *
* *
* IDENTIFICATION * IDENTIFICATION
* $PostgreSQL: pgsql/src/backend/access/transam/xact.c,v 1.293 2010/07/06 19:18:55 momjian Exp $ * $PostgreSQL: pgsql/src/backend/access/transam/xact.c,v 1.294 2010/07/23 00:43:00 rhaas Exp $
* *
*------------------------------------------------------------------------- *-------------------------------------------------------------------------
*/ */
@ -408,10 +408,32 @@ AssignTransactionId(TransactionState s)
/* /*
* Ensure parent(s) have XIDs, so that a child always has an XID later * Ensure parent(s) have XIDs, so that a child always has an XID later
* than its parent. * 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 (isSubXact && !TransactionIdIsValid(s->parent->transactionId)) if (isSubXact && !TransactionIdIsValid(s->parent->transactionId))
AssignTransactionId(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)
AssignTransactionId(parents[--parentOffset]);
pfree(parents);
}
/* /*
* Generate a new Xid and record it in PG_PROC and pg_subtrans. * Generate a new Xid and record it in PG_PROC and pg_subtrans.