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1. Additional fix against ERROR: Child itemid marked as unused

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in CommitTransaction().
2. Changes in GetSnapshotData().
This commit is contained in:
Vadim B. Mikheev 1999-06-03 13:33:13 +00:00
parent f103501286
commit 5541abee0d
2 changed files with 49 additions and 25 deletions
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36
src/backend/access/transam/xact.c
View File

@ -7,7 +7,7 @@
*
*
* IDENTIFICATION
* $Header: /cvsroot/pgsql/src/backend/access/transam/xact.c,v 1.38 1999/06/03 04:41:41 vadim Exp $
* $Header: /cvsroot/pgsql/src/backend/access/transam/xact.c,v 1.39 1999/06/03 13:33:12 vadim Exp $
*
* NOTES
* Transaction aborts can now occur two ways:
@ -646,18 +646,6 @@ RecordTransactionCommit()
FlushBufferPool(!TransactionFlushEnabled());
if (leak)
ResetBufferPool();
/*
* Let others know about no transaction in progress.
* Note that this must be done _before_ releasing locks
* we hold or bad (too high) XmaxRecent value might be
* used by vacuum.
*/
if (MyProc != (PROC *) NULL)
{
MyProc->xid = InvalidTransactionId;
MyProc->xmin = InvalidTransactionId;
}
}
@ -950,6 +938,28 @@ CommitTransaction()
DestroyNoNameRels();
AtEOXact_portals();
RecordTransactionCommit();
/*
* Let others know about no transaction in progress by me.
* Note that this must be done _before_ releasing locks we hold
* and SpinAcquire(ShmemIndexLock) is required - or bad (too high)
* XmaxRecent value might be used by vacuum: UPDATE with xid 0 is
* blocked by xid 1' UPDATE, xid 1 is doing commit while xid 2
* gets snapshot - if xid 2' GetSnapshotData sees xid 1 as running
* then it must see xid 0 as running as well or XmaxRecent = 1
* might be used by concurrent vacuum causing
* ERROR: Child itemid marked as unused
* This bug was reported by Hiroshi Inoue and I was able to reproduce
* it with 3 sessions and gdb. - vadim 06/03/99
*/
if (MyProc != (PROC *) NULL)
{
SpinAcquire(ShmemIndexLock);
MyProc->xid = InvalidTransactionId;
MyProc->xmin = InvalidTransactionId;
SpinRelease(ShmemIndexLock);
}
RelationPurgeLocalRelation(true);
AtCommit_Cache();
AtCommit_Locks();

38
src/backend/storage/ipc/shmem.c
View File

@ -7,7 +7,7 @@
*
*
* IDENTIFICATION
* $Header: /cvsroot/pgsql/src/backend/storage/ipc/shmem.c,v 1.40 1999/05/25 16:11:11 momjian Exp $
* $Header: /cvsroot/pgsql/src/backend/storage/ipc/shmem.c,v 1.41 1999/06/03 13:33:13 vadim Exp $
*
*-------------------------------------------------------------------------
*/
@ -593,6 +593,10 @@ ShmemInitStruct(char *name, unsigned long size, bool *foundPtr)
*
* Strange place for this func, but we have to lookup process data structures
* for all running backends. - vadim 11/26/96
*
* We should keep all PROC structs not in ShmemIndex - this is too
* general hash table...
*
*/
bool
TransactionIdIsInProgress(TransactionId xid)
@ -648,10 +652,7 @@ GetSnapshotData(bool serializable)
snapshot->xip = (TransactionId *) malloc(have * sizeof(TransactionId));
snapshot->xmin = cid;
if (serializable)
snapshot->xmax = cid;
else
ReadNewTransactionId(&(snapshot->xmax));
ReadNewTransactionId(&(snapshot->xmax));
SpinAcquire(ShmemIndexLock);
@ -660,8 +661,10 @@ GetSnapshotData(bool serializable)
{
if (result == (ShmemIndexEnt *) TRUE)
{
if (MyProc->xmin == InvalidTransactionId)
if (serializable)
MyProc->xmin = snapshot->xmin;
/* Serializable snapshot must be computed before any other... */
Assert(MyProc->xmin != InvalidTransactionId);
SpinRelease(ShmemIndexLock);
snapshot->xcnt = count;
return snapshot;
@ -670,13 +673,24 @@ GetSnapshotData(bool serializable)
strncmp(result->key, "PID ", 4) != 0)
continue;
proc = (PROC *) MAKE_PTR(result->location);
xid = proc->xid; /* we don't use spin-locking in xact.c ! */
if (proc == MyProc || xid < FirstTransactionId)
/*
* We don't use spin-locking when changing proc->xid
* in GetNewTransactionId() and in AbortTransaction() !..
*/
xid = proc->xid;
if (proc == MyProc ||
xid < FirstTransactionId || xid >= snapshot->xmax)
{
/*
* Seems that there is no sense to store xid >= snapshot->xmax
* (what we got from ReadNewTransactionId above) in snapshot->xip
* - we just assume that all xacts with such xid-s are running
* and may be ignored.
*/
continue;
}
if (xid < snapshot->xmin)
snapshot->xmin = xid;
else if (xid > snapshot->xmax)
snapshot->xmax = xid;
if (have == 0)
{
snapshot->xip = (TransactionId *) realloc(snapshot->xip,
@ -712,7 +726,7 @@ GetXmaxRecent(TransactionId *XmaxRecent)
Assert(ShmemIndex);
ReadNewTransactionId(XmaxRecent);
*XmaxRecent = GetCurrentTransactionId();
SpinAcquire(ShmemIndexLock);
@ -728,7 +742,7 @@ GetXmaxRecent(TransactionId *XmaxRecent)
strncmp(result->key, "PID ", 4) != 0)
continue;
proc = (PROC *) MAKE_PTR(result->location);
xmin = proc->xmin; /* we don't use spin-locking in xact.c ! */
xmin = proc->xmin; /* we don't use spin-locking in AbortTransaction() ! */
if (proc == MyProc || xmin < FirstTransactionId)
continue;
if (xmin < *XmaxRecent)