On Wed, Feb 14, 2024 at 10:59:57AM -0500, Chet Ramey wrote: > On 2/5/24 10:47 PM, Grisha Levit wrote: > > Bash makes many calls to stdio functions that may have unlocked_stdio(3) > > equivalents. Since the locking functionality provided by the regular > > versions is only useful in multi-threaded applications, it probably makes > > sense for Bash to use the *_unlocked versions where available. > > Thanks for the patch; this looks like a great idea. >
I thought this was only necessary for C programs built with pthreads linked in / -D_REENTRANT. Is that no longer the case? Or has bash started making use of pthreads? When I first learned pthreads ages ago there was a substantial performance hit to the classical stdio-using programs when you built them w/pthreads. It was an important detail to be aware of at the time because so many programs of the era had been written assuming things like getc/ungetc and other character-granular stdio functions were fast functions if not macros. But you didn't incur this hit if you didn't make use of pthreads, which seemed like a conscious choice of the pthreads creators to not impact all such existing software just because a platform added pthreads support. So unless my understanding is wrong/stale or bash has started using pthreads, I don't think this should be necessary. But things do seem to have evolved here; for instance we no longer explicitly add -D_REENTRANT with gcc, instead using -pthread now. Would appreciate any input on the current state of things in this area... Thanks, Vito Caputo
