From 603299167f4aaa857c0156b492ad51143e33fc2f Mon Sep 17 00:00:00 2001 From: Robert Haas Date: Thu, 5 Jan 2017 13:12:16 -0500 Subject: [PATCH] Fix possible leak of semaphore count. Commit 4aec49899e5782247e134f94ce1c6ee926f88e1c reorganized the order of operations here so that we no longer increment the number of "extra waits" before locking the semaphore, but it did not change the starting value of extraWaits from 0 to -1 to compensate. In the worst case, this could leak a semaphore count, but that seems to be unlikely in practice. Discussion: http://postgr.es/m/CAA4eK1JyVqXiMba+-a589Rk0pyHsyKkGxeumVKjU6Y74hdrVLQ@mail.gmail.com Amit Kapila, per an off-list report by Dilip Kumar. Reviewed by me. --- src/backend/storage/ipc/procarray.c | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-) diff --git a/src/backend/storage/ipc/procarray.c b/src/backend/storage/ipc/procarray.c index e5d487dbb7..4adb286d5b 100644 --- a/src/backend/storage/ipc/procarray.c +++ b/src/backend/storage/ipc/procarray.c @@ -491,7 +491,6 @@ ProcArrayGroupClearXid(PGPROC *proc, TransactionId latestXid) volatile PROC_HDR *procglobal = ProcGlobal; uint32 nextidx; uint32 wakeidx; - int extraWaits = -1; /* We should definitely have an XID to clear. */ Assert(TransactionIdIsValid(allPgXact[proc->pgprocno].xid)); @@ -518,6 +517,8 @@ ProcArrayGroupClearXid(PGPROC *proc, TransactionId latestXid) */ if (nextidx != INVALID_PGPROCNO) { + int extraWaits = 0; + /* Sleep until the leader clears our XID. */ for (;;) {