On Sat, 23 Feb 2019 05:54:18, Doug Henderson wrote: > On Fri, 22 Feb 2019 at 17:01, Glyn Gowing <> wrote: > > I have a program (attached) that works correctly on my mac but does > > not work with Cygwin on Windows 10. I'm running the latest version of [snip]
> On further analysis, the call to > > pthread_mutexattr_setpshared(attr, PTHREAD_PROCESS_SHARED); > is failing. The error is EINVAL (22) Invalid argument. > > This suggests that pthread mutexes cannot be shared between processes > by using shared memory in cygwin. I have not attempted to determine if > this is working as expected, or if this is a bug, or a limitation in > the Windows environment. For the record, the output on Linux (FC28): @@ ./Dsmtest2 (Doug's version of the original smtest2.c) 1551022585 - both : attr, lock, lock->next: 0x7f4ec2ceb000 0x7f4ec2cec000 0x7f4ec2cec000 1551022585 - Parent: acquiring lock (0x7f4ec2cec000) 1551022585 - Parent: acquired lock (0x7f4ec2cec000) - Before sleeping 10 seconds. 1551022585 - Child : checking lock (0x7f4ec2cec000) - Before sleeping 5 seconds. 1551022590 - Child : acquiring lock (0x7f4ec2cec000) - After sleeping 5 seconds. 1551022595 - Parent: unlocking lock (0x7f4ec2cec000) - After sleeping 10 seconds. 1551022595 - Parent: unlocked lock (0x7f4ec2cec000) - Before sleeping 5 seconds to let child catch up. 1551022595 - Child : acquired lock (0x7f4ec2cec000) - Before sleeping 3 seconds. 1551022598 - Child : unlocking lock (0x7f4ec2cec000) - After sleeping 3 seconds. 1551022598 - Child : unlocked lock (0x7f4ec2cec000). 1551022600 - - After sleeping 5 seconds to let child catch up. @@ ... as I understand it, this is between a parent thread and a child thread, after fork(), -- and only these two! -- using mutexes in shared memory, that is, shared memory between the two processes (parent and child) ... Logically, I would say, the same as 2 threads in one process ... (and yes, in general, all threads are "dead" after fork(), except for the thread that is the child of the calling thread). Henri -- Problem reports: http://cygwin.com/problems.html FAQ: http://cygwin.com/faq/ Documentation: http://cygwin.com/docs.html Unsubscribe info: http://cygwin.com/ml/#unsubscribe-simple
