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| author | Tom Lane <tgl@sss.pgh.pa.us> | 2019-07-29 18:49:04 -0400 |
|---|---|---|
| committer | Tom Lane <tgl@sss.pgh.pa.us> | 2019-07-29 18:49:04 -0400 |
| commit | c3b613e1b0e5a83e36ffb14089bad1d4a5880208 (patch) | |
| tree | ccc97b9e57422b08b76219e45cbf51c8f33477f3 /src/backend/parser/parse_func.c | |
| parent | 484a4667bbed9c0c3ee47a41a75ea8d7c48444e5 (diff) | |
Fix busted logic for parallel lock grouping in TopoSort().
A "break" statement erroneously left behind by commit a1c1af2a1
caused TopoSort to do the wrong thing if a lock's wait list
contained multiple members of the same locking group.
Because parallel workers don't normally need any locks not already
taken by their leader, this is very hard --- maybe impossible ---
to hit in production. Still, if it did happen, the queries involved
in an otherwise-resolvable deadlock would block until canceled.
In addition to removing the bogus "break", add an Assert showing
that the conflicting uses of the beforeConstraints[] array (for both
counts and flags) don't overlap, and add some commentary explaining
why not; because it's not obvious without explanation, IMHO.
Original report and patch from Rui Hai Jiang; additional assert
and commentary by me. Back-patch to 9.6 where the bug came in.
Discussion: https://postgr.es/m/CAEri+mLd3bpHLyW+a9pSe1y=aEkeuJpwBSwvo-+m4n7-ceRmXw@mail.gmail.com
Diffstat (limited to 'src/backend/parser/parse_func.c')
0 files changed, 0 insertions, 0 deletions