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Win SBCL 64-bit - can trigger "GC Invariant Lost" in web server #15

supergrade opened this Issue Dec 20, 2011 · 8 comments

2 participants


SBCL 64-bit

Pull the "Wreck" project

Edit wreck.lisp to point prog-lisp-dir to the base directory of the code:
(defvar prog-lisp-dir "c:/prog/wreck/")

Now, put the contents of wreck.lisp into the clipboard

Start TWO command-line instances of SBCL Win (threading) 64-bit, SERVER and CLIENT

On the SERVER:
1. Paste contents of wreck.lisp
2. Run (start-server)

This should have it listening on port 82

1. Paste contents of wreck.lisp
2. Run (start-stress-test) - it runs multiple threads that keep connecting to port 82 local
3. Run (show-progress) a few times. You should be seeing growing integers for both "Success" and "Errors". Errors are fine, you will see MUCH more errors than Successes; but that's okay (not the point of the exercise).

The client is now connecting/disconnecting from the server rapidly, with the server only accepting some of the connections. This is as-intended.

Within about 4 hours (for me) the SERVER will crash to LDB:

  • fatal error encountered in SBCL pid 10604(tid 10225392): GC invariant lost, file "gencgc.c", line 3525

When you have time, please try to crash my new build (commit 7c91a84). I hope that the cause of GC invariant loss is fixed there.


Well, I pulled the 1154 on the download site, and now the "stress test" corrupts/freezes the server in under a minute. From the server (as set up in the instructions above), in short order, you get to enter one thing in the REPL and then it's over. . . . (lockup). No error messages or break to LDB.

The OLD 1150 works fine (well, I assume it still has this bug but it doesn't lock up quickly, something changed recently broke it).

1. I just switched from V64 to Win 7 - long story
2. In Windows 7 there's a compile error with this hunchentoot, don't know why, not sure I care; but maybe it hampers your testing. I've checked in a new commit to "wreck" to work around it.

But in Win7, the 1150 build does run longer than the 1154 - I haven't tested 1150 in Win 7 to breakage yet, I'll leave it running tonight; but I assume something bad happened 1150->1154


I believe that the problem is fixed with the latest build 1162 (commit e2fec1b).


1162 still fails like the other >1150 builds, the server freezes up, it just took a bit longer.


Thank you again. I really hope it gets better with 1165 (uploaded recently). When you have time, please give it a try.


1162 lasted almost 8 hours in my last test. I'll restart the test now with 1165.

Thank you for your work on this. I'm aiming for an utterly infallible 64-bit windows prod-server-grade common lisp. You're probably converging on one. . .


My test has lasted 24 hours without failure. I think you can close the issue as of 1165. . ..

@supergrade supergrade closed this Dec 31, 2011
@supergrade supergrade reopened this Jan 1, 2012

It locked at 34 hours. Very long test cycle on this; but relevant for being able to use it on a server.

Basically, I run "Wreck" in 2 command windows, and the server one locks up. By "locks up" in the examples above, either the repl takes one input, or (as I had it running a loop printing an incrememting value every 1 second) it just stops.

Ctrl-C does not work, and the server is no longer responding.

Is there something we can put in SBCL or the program to help identify this?

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