On Mon, Jan 10, 2022 at 8:06 AM Thomas Munro <thomas.mu...@gmail.com> wrote:
> On Mon, Jan 10, 2022 at 12:00 AM Alexander Lakhin <exclus...@gmail.com> wrote:
> > Going down through the call chain, I see that at the end of it
> > WaitForMultipleObjects() hangs while waiting for the primary connection
> > socket event. So it looks like the socket, that is closed by the
> > primary, can get into a state unsuitable for WaitForMultipleObjects().
>
> I wonder if FD_CLOSE is edge-triggered, and it's already told us once.
Can you reproduce it with this patch?
From d3cfff53911ce068d4a31fe7ac7933958936d1b0 Mon Sep 17 00:00:00 2001
From: Thomas Munro <thomas.mu...@gmail.com>
Date: Mon, 10 Jan 2022 14:45:05 +1300
Subject: [PATCH] Make Windows FD_CLOSE reporting sticky.
XXX Just testing an idea...
---
src/backend/storage/ipc/latch.c | 16 ++++++++++++++++
src/include/storage/latch.h | 1 +
2 files changed, 17 insertions(+)
diff --git a/src/backend/storage/ipc/latch.c b/src/backend/storage/ipc/latch.c
index 1d893cf863..4a61b31cd5 100644
--- a/src/backend/storage/ipc/latch.c
+++ b/src/backend/storage/ipc/latch.c
@@ -899,6 +899,7 @@ AddWaitEventToSet(WaitEventSet *set, uint32 events, pgsocket fd, Latch *latch,
event->user_data = user_data;
#ifdef WIN32
event->reset = false;
+ event->closed = false;
#endif
if (events == WL_LATCH_SET)
@@ -1882,6 +1883,20 @@ WaitEventSetWaitBlock(WaitEventSet *set, int cur_timeout,
return 1;
}
}
+
+ /*
+ * XXX: HYPOTHESIS TO TEST
+ * Windows only reports FD_CLOSE once. If we've seen that already,
+ * continue to report it.
+ */
+ if ((cur_event & WL_SOCKET_MASK) && cur_event->closed)
+ {
+ occurred_events->pos = cur_event->pos;
+ occurred_events->user_data = cur_event->user_data;
+ occurred_events->events = (cur_event->events & WL_SOCKET_MASK);
+ occurred_events->fd = cur_event->fd;
+ return 1;
+ }
}
/*
@@ -2002,6 +2017,7 @@ WaitEventSetWaitBlock(WaitEventSet *set, int cur_timeout,
{
/* EOF/error, so signal all caller-requested socket flags */
occurred_events->events |= (cur_event->events & WL_SOCKET_MASK);
+ cur_event->closed = true;
}
if (occurred_events->events != 0)
diff --git a/src/include/storage/latch.h b/src/include/storage/latch.h
index 44f9368c64..c24f46dc37 100644
--- a/src/include/storage/latch.h
+++ b/src/include/storage/latch.h
@@ -147,6 +147,7 @@ typedef struct WaitEvent
void *user_data; /* pointer provided in AddWaitEventToSet */
#ifdef WIN32
bool reset; /* Is reset of the event required? */
+ bool closed; /* Has FD_CLOSE event been reported? */
#endif
} WaitEvent;
--
2.33.1
