Arrange for GetSnapshotData to copy live-subtransaction XIDs from the
Tom Lane <tgl@sss.pgh.pa.us>
Arrange for GetSnapshotData to copy live-subtransaction XIDs from the PGPROC array into snapshots, and use this information to avoid visits to pg_subtrans in HeapTupleSatisfiesSnapshot. This appears to solve the pg_subtrans-related context swap storm problem that's been reported by several people for 8.1. While at it, modify GetSnapshotData to not take an exclusive lock on ProcArrayLock, as closer analysis shows that shared lock is always sufficient. Itagaki Takahiro and Tom Lane
Files
| Path | Change | +/− |
|---|---|---|
| src/backend/access/transam/varsup.c | modified | +17 −6 |
| src/backend/storage/ipc/procarray.c | modified | +59 −10 |
| src/backend/utils/time/tqual.c | modified | +100 −66 |
| src/include/utils/tqual.h | modified | +7 −1 |