On 11/1/2026 2:12 PM, Bryan Green wrote:
> On 11/1/2026 2:03 PM, Bryan Green wrote:
>> On 11/6/2025 7:59 PM, Thomas Munro wrote:
>>> On Fri, Nov 7, 2025 at 2:35 PM Bryan Green <dbryan(dot)green(at)gmail(dot)com> wrote:
>>>> If you agree, and I think you do, I will implement the SOCK_CLOEXEC
>>>> abstraction and the socket_set_cloexec helper for this. My bug fix will
>>>> be the first user.
>>>
>>> +1
>>>
>>> Thanks for working on all this stuff.
>>>
>>>> I also need to handle the handles for shared memory and pipes. I will
>>>> probably just write those up tonight and share for review and discussion.
>>>
>>> Cool.
>>
>> After a long wait... here's v2! It's two patches now. 0002 is the
>> shared memory fix I said would follow back in November.
>>
>> 0001 does sockets the way Thomas suggested. Backend code on Windows
>> now gets a SOCK_CLOEXEC, which pgwin32_socket() maps to
>> WSA_FLAG_NO_HANDLE_INHERIT, so you ask for a non-inheritable socket
>> the same way you do on Unix instead of v1's blanket change. The listen
>> sockets ask for it.
>>
>> The macro is backend-only, since libpq passes SOCK_CLOEXEC whenever
>> it's defined and Winsock would reject it. I left accept4() out. It
>> only matters once we have threads.
>>
>> Regarding 0002, the postmaster made its shared memory handle
>> inheritable on purpose, so children could use the same handle value.
>> That also gave it to everything the children run. If the server dies
>> while one of those is still running, the next postmaster fails with
>> "pre-existing shared memory block is still in use". Now the
>> postmaster's handle isn't inheritable, and save_backend_variables()
>> duplicates it into each child, the way the signal pipe already is.
>> Neither copy in the child is inheritable. That covers every child, not
>> just backends.
>>
>> The test (src/test/postmaster/t/005_handle_inheritance.pl) uses
>> Harrison's idea of running the program with server-side COPY TO
>> PROGRAM. v1's test used \copy, which made the program psql's child, so
>> it couldn't have caught anything. The program is a small Perl script
>> that outlives an immediate stop. 0001 checks that the client sees its
>> connection drop and that the port can be bound again-- 0002 adds a
>> restart. All fail on master and pass with the patches. Tested with
>> MSVC on Windows 11 (regress, recovery, isolation, postmaster, pg_ctl,
>> libpq).
>>
>> Harrison, thanks for looking at this. I didn't need force_initdb here.
>> If you saw failures without it, what were they?
>>
> Obviously...here are the patches.
>
v2's test assumed TCP, and failed on Windows CI, which uses Unix-domain
sockets (PG_TEST_USE_UNIX_SOCKETS). v3 has the node listen on 127.0.0.1
as well and checks that, and lets the program go if the test dies
early. No code changes otherwise. Passes on all CI tasks in my fork.
--
Bryan Green
EDB: https://www.enterprisedb.com