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Add temporary debug logging, in 9.4 branch only.

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Commit 5ee940e1c served its purpose by demonstrating that buildfarm
member okapi is seeing some sort of locally-visible state mismanagement,
not a cross-process data visibility problem as I'd first theorized.
Put in some elog(LOG) messages in hopes of gathering more info about
exactly what's happening there.  Again, this is temporary code to be
reverted once we have buildfarm results.

Discussion: https://postgr.es/m/6744.1523833660@sss.pgh.pa.us
This commit is contained in:
Tom Lane 2018-04-16 13:44:39 -04:00
parent fea5bfde16
commit e55380f3b6
3 changed files with 22 additions and 0 deletions
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6
src/backend/commands/indexcmds.c
View File

@ -758,6 +758,8 @@ DefineIndex(Oid relationId,
*/
validate_index(relationId, indexRelationId, snapshot);
PrintSnapMgrStatus("concurrent index build, before snapshot release");
/*
* Drop the reference snapshot. We must do this before waiting out other
* snapshot holders, else we will deadlock against other processes also
@ -770,9 +772,13 @@ DefineIndex(Oid relationId,
limitXmin = snapshot->xmin;
PopActiveSnapshot();
PrintSnapMgrStatus("concurrent index build, after PopActiveSnapshot");
UnregisterSnapshot(snapshot);
PrintSnapMgrStatus("concurrent index build, after UnregisterSnapshot");
InvalidateCatalogSnapshot();
PrintSnapMgrStatus("concurrent index build, after InvalidateCatalogSnapshot");
/*
* The index is now valid in the sense that it contains all currently
* interesting tuples. But since it might not contain tuples deleted just

14
src/backend/utils/time/snapmgr.c
View File

@ -1401,3 +1401,17 @@ HistoricSnapshotGetTupleCids(void)
Assert(HistoricSnapshotActive());
return tuplecid_data;
}
void
PrintSnapMgrStatus(const char *context)
{
int asdepth = 0;
ActiveSnapshotElt *active;
for (active = ActiveSnapshot; active != NULL; active = active->as_next)
asdepth++;
elog(LOG, "%s: %d reg snaps, %d active snaps, cat snap %p, xmin %u",
context, RegisteredSnapshots, asdepth,
CatalogSnapshot, MyPgXact->xmin);
}

2
src/include/utils/snapmgr.h
View File

@ -65,4 +65,6 @@ extern void SetupHistoricSnapshot(Snapshot snapshot_now, struct HTAB *tuplecids)
extern void TeardownHistoricSnapshot(bool is_error);
extern bool HistoricSnapshotActive(void);
extern void PrintSnapMgrStatus(const char *context);
#endif /* SNAPMGR_H */