SHOPT_SPAWN => use the ast spawnveg() the posix_spawn vs vfork vs fork iffe test results are used by the libast spawnveg() implementation
-- Glenn Fowler -- AT&T Research, Florham Park NJ -- On Mon, 30 Oct 2006 05:25:28 +0100 Roland Mainz wrote: > Glenn Fowler wrote: > > > Should ksh93/libshell use |posix_spawn()| instead of |vfork()| ? > > > > it should and it does > > > > all ast and ksh fork()/exec() is done by the ast spawnveg() > > which configures to the local system at compile time > > if posix_spawn is available then it is used > > a few other non-standard fork+exec combinations are also checked > > before vfork+exec, finally defaulting to fork+exec > > > > note that there are instances where ksh prefers pure fork() > > although it can work around that too > Quick test: I've set "-DSHOPT_SPAWN" at built time (since the > buildlog.log doesn't list SHOPT_SPAWN when compiling ast-ksh) but ksh93 > still calls |vfork()|: > -- snip -- > ksh93 -o gmacs > $ ls > stopped in _vfork at 0xff23725c > 0xff23725c: _vfork : mov 3, %o0 > stopped in _vfork at 0xff23725c > 0xff23725c: _vfork : mov 3, %o0 > (dbx) where > =>[1] _vfork(0x1, 0xff0ead00, 0xff0eacfc, 0xffbfdb40, 0x9eeb4, 0xbc00), > at 0xff23725c > [2] spawnveg(0x28242, 0x280d8, 0x28104, 0x1, 0x280a1, 0x27710), at > 0xff05e538 > [3] _spawnveg(0x28242, 0x1, 0xff38f678, 0xff38c000, 0x0, 0x44848), at > 0xff3477f0 > [4] path_spawn(0xffffffff, 0x280d8, 0x28240, 0x3d, 0x3, 0x28242), at > 0xff349778 > [5] sh_ntfork(0xff38c000, 0x1, 0xff38f678, 0xff38f220, 0xff38c000, > 0x0), at 0xff359a00 > [6] sh_exec(0x280a8, 0x24, 0xff38f220, 0x232f0, 0x65ab0, 0xff0eac40), > at 0xff3551a4 > [7] exfile(0xff38f220, 0x280a8, 0x34, 0xff38f678, 0xff38f678, > 0xff38c000), at 0xff318e60 > [8] sh_main(0xff38f220, 0x319c8, 0xff38c000, 0xff38c000, 0xff38c000, > 0xff38c000), at 0xff3183b0 > -- snip -- > ;-( > I've removed "-DSHOPT_SPAWN" from the built options but |vfork()| still > gets called (=no change) ... ;-( > ---- > Bye, > Roland > -- > __ . . __ > (o.\ \/ /.o) roland.mainz at nrubsig.org > \__\/\/__/ MPEG specialist, C&&JAVA&&Sun&&Unix programmer > /O /==\ O\ TEL +49 641 7950090 > (;O/ \/ \O;)
