[Sbcl-devel] PATCH: change with-concurrent-access-check so that it ignores concurrent reads

[Attila L. <att...@gm...>]

hi,

when :sb-hash-table-debug is enabled in customize-target-features.lisp
then sbcl checks for concurrent access to hashtables. but Juho said on
#lisp that concurrent reads are safe, so i've changed it to only
signal when there's a writer involved. hopefully the code is correct,
although i think it may not detect 100% of the concurrent accesses,
but good enough to bring up the debugger.

we are running a high load site with sbcl and suspecting that many of
the crashes are happening due to unprotected hashtable access in
sbcl's internal structures. i'll send some interesting backtraces in
upcoming mails.

the code is heavily threaded, running on machines with 4 cores.

hth,

-- 
 attila