wineserver sometimes crashes in fd.c:1548: set_fd_events: Assertion `poll_users[user] == fd' failed

[Mihai Todor]

Hello Everyone,

I am using Wine 3.0 stable and, as part of my setup, I am running
wineserver in persistent mode forever (wineserver -p) for performance
reasons and, sometimes, it dies with this error: "wineserver:
fd.c:1548: set_fd_events: Assertion `poll_users[user] == fd' failed."

For the time being, this is a sufficiently rare occurrence to not
concern me (it happens once / day or so), but I am curious to learn
what might cause it, since it looks like a bug.

For a bit more detail about my setup, while wineserver is running, I
am starting a single instance of an x86 application with an embedded
gRPC TCP server, I am instructing this application to process some
local files and, after it finishes, I am stopping it. This cycle
repeats once every 10 - 20 seconds on average and there is just one
instance of this application running at the same time. Sometimes, this
application hangs and I terminate it forcefully by killing the process
(bad input file / bad code / etc), which is what I am thinking might
be the cause of the wineserver crash. However, so far, I was unable to
reproduce this issue consistently.

I am considering to spend some time adding more logging in the
wineserver code to narrow it down, but I'd be grateful if anyone has
any insight into what might be the cause and how to diagnose it.

Thanks,
Mihai