I do my development in Ubuntu-22.04 Linux running on the Windows Subshell for Linux. I recently got a laptop refresh and the latest software doesn’t run. The fix is obscure, so I thought I’d document it.
sbcl runs fine out of the box in WSL2, but I’m encountering a bug where TCP connections to one particular server are being left in the CLOSE_WAIT state indefinitely. After several minutes, I hit the limit on the number of open files.
The “right thing” would be to track down who isn’t
closing the connection properly, but it’s only a few hundred
connections. It appears that ulimit is set to 1024,
which is pretty easy to hit with this bug.
Bumping ulimit to something more reasonable is a lazy
workaround. It isn’t a solution — I’m still leaking open
files — but I’ll be able to leak thousands of them without
having problems.
But increasing nofiles turned out to be a problem. I
edited all the magic files in /etc until they all said
I could have 131071 open files. When I re-started WSL, all the ways
I could start a shell agreed that the ulimit was
131071, yet when I started sbcl and ran this:
(uiop:run-program "prlimit" :output *standard-output*) RESOURCE DESCRIPTION SOFT HARD UNITS AS address space limit unlimited unlimited bytes CORE max core file size 0 unlimited bytes CPU CPU time unlimited unlimited seconds DATA max data size unlimited unlimited bytes FSIZE max file size unlimited unlimited bytes LOCKS max number of file locks held unlimited unlimited locks MEMLOCK max locked-in-memory address space 67108864 67108864 bytes MSGQUEUE max bytes in POSIX mqueues 819200 819200 bytes NICE max nice prio allowed to raise 0 0 NOFILE max number of open files 1024 1048576 files NPROC max number of processes 62828 62828 processes RSS max resident set size unlimited unlimited bytes RTPRIO max real-time priority 0 0 RTTIME timeout for real-time tasks unlimited unlimited microsecs SIGPENDING max number of pending signals 62828 62828 signals STACK max stack size 8388608 unlimited bytes NIL NIL 0 (0 bits, #x0, #o0, #b0)
The limit was at the old value of 1024.
WSL launched sbcl without a shell, so
the ulimit setting was not being run.
The solution is easy, but it took me a long time to figure it out.
Not only do you need to edit all the magic in /etc, and
add ulimit statements to your .bashrc, you
should also add ulimit statements to
your .profile, and then instruct wsl to
launch your program under a login shell:
(require ’sly)
(setq sly-lisp-implementations
’((sbcl ("C:\\Program Files\\WSL\\wsl.exe"
"--distribution-id" "{df4f07a6-2142-405c-8a6a-63f1ca3a7e8d}"
"--cd" "~"
"--shell-type" "login"
"/usr/local/bin/sbcl")
)))
This bit of insanity allows me to run sbcl with 131071
open files in Linux as my inferior lisp program in a Windows Emacs
running SLY. (Running Emacs under Windows gives me a way to use a
modified Dvorak keyboard. I could run Emacs in the Linux subsystem,
but the Wayland server is in a container and doesn’t let you modify
the keyboard.)
