From 92f678b6cef5a6b5a8fbd7d05b201987d52a8060 Mon Sep 17 00:00:00 2001 From: Thomas Munro Date: Thu, 29 Nov 2018 12:24:07 +1300 Subject: [PATCH] Detach from DSM segments last in resowner.c. It turns out that Windows' FILE_SHARE_DELETE mode doesn't quite give POSIX semantics for unlink(). While it lets you unlink a file or a directory that has an open handle, it doesn't let you unlink a directory that previously contained a file that has an open handle. This has the consequence that an error raised while a SharedFileSet exists can cause us to fail to unlink a temporary directory, even though all the files within it have been unlinked. We log a WARNING and leak the empty directory until the next restart eventually cleans it up. Fix, by detaching from DSM segments only after we have closed all file handles. Since SharedFileSet uses a DSM detach hook to unlink files only when the last backend detaches, it's only our own file handles that we have to worry about. This was a secondary issue discovered while investigating bug #15460. Author: Thomas Munro Discussion: https://postgr.es/m/15460-b6db80de822fa0ad@postgresql.org Discussion: https://postgr.es/m/CAEepm=1Ugp7mNFX-YpSfWr0F_6QA4jzjtavauBcoAAZGd7_tPA@mail.gmail.com --- src/backend/utils/resowner/resowner.c | 20 ++++++++++---------- 1 file changed, 10 insertions(+), 10 deletions(-) diff --git a/src/backend/utils/resowner/resowner.c b/src/backend/utils/resowner/resowner.c index 211833da02c..004693234ea 100644 --- a/src/backend/utils/resowner/resowner.c +++ b/src/backend/utils/resowner/resowner.c @@ -535,16 +535,6 @@ ResourceOwnerReleaseInternal(ResourceOwner owner, RelationClose(res); } - /* Ditto for dynamic shared memory segments */ - while (ResourceArrayGetAny(&(owner->dsmarr), &foundres)) - { - dsm_segment *res = (dsm_segment *) DatumGetPointer(foundres); - - if (isCommit) - PrintDSMLeakWarning(res); - dsm_detach(res); - } - /* Ditto for JIT contexts */ while (ResourceArrayGetAny(&(owner->jitarr), &foundres)) { @@ -668,6 +658,16 @@ ResourceOwnerReleaseInternal(ResourceOwner owner, PrintFileLeakWarning(res); FileClose(res); } + + /* Ditto for dynamic shared memory segments */ + while (ResourceArrayGetAny(&(owner->dsmarr), &foundres)) + { + dsm_segment *res = (dsm_segment *) DatumGetPointer(foundres); + + if (isCommit) + PrintDSMLeakWarning(res); + dsm_detach(res); + } } /* Let add-on modules get a chance too */ -- 2.19.1