From 884a60840cd684dd7925e7a4f9bf10288c37694d Mon Sep 17 00:00:00 2001 From: Robert Haas Date: Wed, 13 Dec 2017 16:09:00 -0500 Subject: [PATCH] Fix parallel index scan hang with deleted or half-dead pages. The previous coding forgot to release the scan before seizing it again, leading to a lockup. Report by Patrick Hemmer. Diagnosis by Thomas Munro. Patch by Amit Kapila. Discussion: http://postgr.es/m/CAEepm=2xZUcOGP9V0O_G0=2P2wwXwPrkF=upWTCJSisUxMnuSg@mail.gmail.com --- src/backend/access/nbtree/nbtsearch.c | 10 ++++++++++ 1 file changed, 10 insertions(+) diff --git a/src/backend/access/nbtree/nbtsearch.c b/src/backend/access/nbtree/nbtsearch.c index 558113bd13..12d3f081b6 100644 --- a/src/backend/access/nbtree/nbtsearch.c +++ b/src/backend/access/nbtree/nbtsearch.c @@ -1486,6 +1486,11 @@ _bt_readnextpage(IndexScanDesc scan, BlockNumber blkno, ScanDirection dir) if (_bt_readpage(scan, dir, P_FIRSTDATAKEY(opaque))) break; } + else if (scan->parallel_scan != NULL) + { + /* allow next page be processed by parallel worker */ + _bt_parallel_release(scan, opaque->btpo_next); + } /* nope, keep going */ if (scan->parallel_scan != NULL) @@ -1581,6 +1586,11 @@ _bt_readnextpage(IndexScanDesc scan, BlockNumber blkno, ScanDirection dir) if (_bt_readpage(scan, dir, PageGetMaxOffsetNumber(page))) break; } + else if (scan->parallel_scan != NULL) + { + /* allow next page be processed by parallel worker */ + _bt_parallel_release(scan, BufferGetBlockNumber(so->currPos.buf)); + } /* * For parallel scans, get the last page scanned as it is quite