Dear Ivan, Thanks for the reply. I am pressurised by a fast approaching deadline and your reply calmed me...
Take a look at the following code: debug at <tmp>#26: LYG <- mclapply(LYGH, FUN = arfima, mc.cores = 2, mc.preschedule = FALSE) Browse[2]> length(LYGH) [1] 357 Browse[2]> ^C Browse[2]> LYG <- pbmclapply(LYGH,FUN = arfima,mc.cores = 2,mc.preschedule = FALSE) | | 0%, ETA NA I am debuuging a function FUN wherein the above expressions appear. The pbmclapply code works well if called inside FUN: > FUN(arg) Result.. But as you may note, it doesn't work while in debug mode.... Also, if I replace pbmclapply by maclapply inside FUN, it hangs.... You might be interested in this: [ec2-user@ip-172-31-15-116 ~]$ exit logout There are stopped jobs. THis occurs when I close R and try to exit the shell prompt( I am on an AWS EC2 RHEL 8 Instance). Can this lead you somewhere? As of now I have quit R in my machine, so I can't get session info..but please let me know if you need it necessarily... by the by, how do you run top when running R? I think at least in my machine, you have to quit R to get to the shell prompt... I request you TO PLEASE reply to this mail as early as possible. I am facing an imminent deadline...please excuse my blatant violation of protocol, but deadlines are deadlines, right? THanking you, Yours sincerely, AKSHAY M KULKARNI ________________________________ From: Ivan Krylov <krylov.r...@gmail.com> Sent: Saturday, June 10, 2023 1:43 AM To: akshay kulkarni <akshay...@hotmail.com> Cc: R help Mailing list <r-help@r-project.org> Subject: Re: [R] inconsistency in mclapply..... On Fri, 9 Jun 2023 18:01:44 +0000 akshay kulkarni <akshay...@hotmail.com> wrote: > > LYG <- pbmclapply(LYGH,FUN = arfima,mc.cores = 2,mc.preschedule = > > FALSE) > | > > | > 0%, ETA NA^ > > It just hangs. My questions from the last time still stand: 0) What is your sessionInfo()? Maybe you're running a parallel BLAS which doesn't always handle fork() or something. It may be worth disabling BLAS-level parallelism as long as you're already trying to use 100% of your processor by other means. 1) What does traceback() show after you interrupt pbmclapply? Most likely, you would be interrupting selectChildren(), but if not, the problem may lie in a very different place from what I'm expecting. 2) While pbmclapply is hung, without interrupting it, take a look at the state of the system and the processes on it (are you still on RHEL? use `top` or whatever task manager you're comfortable with). a) Is 100% of the CPU being used? 100% of one core? Is system mostly idle? b) Can you find the child processes launched by pbmclapply? c) Write down the PID of the child process and attach a debugger to it (If you're on RHEL, try following this guide: <https://beej.us/guide/bggdb/#attach>. If GDB asks you to install additional debug symbols by running debuginfo-install, follow its guidance and then restart GDB.) and obtain a backtrace. (In GDB, the command to obtain a backtrace is "backtrace".) Which function is the child process stuck in? -- Best regards, Ivan [[alternative HTML version deleted]] ______________________________________________ R-help@r-project.org mailing list -- To UNSUBSCRIBE and more, see https://stat.ethz.ch/mailman/listinfo/r-help PLEASE do read the posting guide http://www.R-project.org/posting-guide.html and provide commented, minimal, self-contained, reproducible code.