[ clisp-Bugs-3243683 ] (posix:wait) race condition

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Bugs item #3243683, was opened at 2011-03-25 08:34
Message generated for change (Comment added) made by sds
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Category: clisp
Group: lisp error
Status: Open
Resolution: None
Priority: 5
Private: No
Submitted By: Bill Evans (mariposabill)
Assigned to: Bruno Haible (haible)
Summary: (posix:wait) race condition

Initial Comment:
My abject apologies if this is a feature, not a bug.

The response to artifact 3224360 was that I should avoid (linux:waitpid) and use (posix:wait) instead.  This presents a race condition (to say the least) if the child process finishes before the parent can get around to waiting for it, as the following will demonstrate.

=== platform:
Linux tiger 2.6.26-2-686 #1 SMP Sat Dec 26 09:01:51 UTC 2009 i686 GNU/Linux
=== compiler version:
gcc (Debian 4.3.2-1.1) 4.3.2
Copyright (C) 2008 Free Software Foundation, Inc.
This is free software; see the source for copying conditions.  There is NO
warranty; not even for MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.

=== glibc version:
/lib/libc-2.7.so
=== clisp version:
GNU CLISP 2.49 (2010-07-07) (built 3510043534) (memory 3510043839)
Software: GNU C 4.3.2 
gcc -g -O2 -W -Wswitch -Wcomment -Wpointer-arith -Wimplicit -Wreturn-type -Wmissing-declarations -Wno-sign-compare -Wno-format-nonliteral -O2 -fexpensive-optimizations -falign-functions=4 -DENABLE_UNICODE -DDYNAMIC_FFI -DDYNAMIC_MODULES -I.  -lreadline -lncurses -ldl -lavcall -lcallback  -lsigsegv libgnu_cl.a 
SAFETY=0 HEAPCODES LINUX_NOEXEC_HEAPCODES GENERATIONAL_GC SPVW_BLOCKS SPVW_MIXED TRIVIALMAP_MEMORY
libsigsegv 2.5
libreadline 5.2
Features: 
(READLINE REGEXP SYSCALLS I18N LOOP COMPILER CLOS MOP CLISP ANSI-CL COMMON-LISP LISP=CL INTERPRETER SOCKETS
 GENERIC-STREAMS LOGICAL-PATHNAMES SCREEN FFI GETTEXT UNICODE BASE-CHAR=CHARACTER PC386 UNIX)
C Modules: (clisp i18n syscalls regexp readline)
Installation directory: /u/wally/public_html/doc/lisp/bug3/sandbox/
User language: ENGLISH
Machine: I686 (I686) tiger.x441afea5.org [10.0.0.1]

I downloaded the currently released version of clisp today (25 Mar 2011) from http://ftp.gnu.org/pub/gnu/clisp/latest.

I built it the normal way, as shown in the attached script. That script downloads the source, builds and installs clisp, copies "full" so it sits next to "base" (I still don't understand why I had to do that), and runs the program.

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>Comment By: Sam Steingold (sds)
Date: 2011-03-25 10:17

Message:
I don't know why you think you need to copy full anywhere.
http://clisp.org/impnotes/clisp.html#opt-link-set
http://clisp.org/impnotes/modules.html#base-modules

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