Re: [OMPI users] Singleton process spawns additional thread
Sorry for the delay - I have tracked this down and fixed it. The fix will be included in 1.10.2. Thanks for bringing it to our attention! Ralph > On Jan 7, 2016, at 9:38 PM, Ralph Castain <r...@open-mpi.org> wrote: > > A singleton will indeed have an extra thread, but it should be quiescent. > I’ll check the 1.10.2 release candidate and see if it still exhibits that > behavior. > > >> On Jan 7, 2016, at 9:32 PM, Au Eelis <auee...@gmail.com> wrote: >> >> Hi! >> >> It is in so far related, that one of these threads is actually doing >> something. >> >> Btw, I noticed this on two separate machines! A computing cluster with >> admin-built openmpi and Archlinux with openmpi from the repositories. >> >> However, running the code with openmpi 1.6.2 and ifort 13.0.0 does not show >> this behaviour. >> >> Best regards, >> Stefan >> >> >> >> On 01/07/2016 03:27 PM, Sasso, John (GE Power, Non-GE) wrote: >>> Stefan, I don't know if this is related to your issue, but FYI... >>> >>> >>>> Those are async progress threads - they block unless something requires >>>> doing >>>> >>>> >>>>> On Apr 15, 2015, at 8:36 AM, Sasso, John (GE Power & Water, Non-GE) >>>>> <john1.sa...@ge.com> wrote: >>>>> >>>>> I stumbled upon something while using 'ps -eFL' to view threads of >>>>> processes, and Google searches have failed to answer my question. This >>>>> question holds for OpenMPI 1.6.x and even OpenMPI 1.4.x. >>>>> >>>>> For a program which is pure MPI (built and run using OpenMPI) and does >>>>> not implement Pthreads or OpenMP, why is it that each MPI task appears as >>>>> having 3 threads: >>>>> >>>>> UID PID PPID LWP C NLWPSZ RSS PSR STIME TTY TIME >>>>> CMD >>>>> sasso 20512 20493 20512 993 187849 582420 14 11:01 ? 00:26:37 >>>>> /home/sasso/mpi_example.exe >>>>> sasso 20512 20493 20588 03 187849 582420 11 11:01 ? 00:00:00 >>>>> /home/sasso/mpi_example.exe >>>>> sasso 20512 20493 20599 03 187849 582420 12 11:01 ? 00:00:00 >>>>> /home/sasso/mpi_example.exe >>>>> >>>>> whereas if I compile and run a non-MPI program, 'ps -eFL' shows it >>>>> running as a single thread? >>>>> >>>>> Granted the CPU utilization (C) for 2 of the 3 threads is zero, but the >>>>> threads are bound to different processors (11,12,14). I am curious as >>>>> to why this is, and no complaining that there is a problem. Thanks! >>>>> >>>>> --john >>> >>> >>> -Original Message- >>> From: users [mailto:users-boun...@open-mpi.org] On Behalf Of Au Eelis >>> Sent: Thursday, January 07, 2016 7:10 AM >>> To: us...@open-mpi.org >>> Subject: [OMPI users] Singleton process spawns additional thread >>> >>> Hi! >>> >>> I have a weird problem with executing a singleton OpenMPI program, where an >>> additional thread causes full load, while the master thread performs the >>> actual calculations. >>> >>> In contrast, executing "mpirun -np 1 [executable]" performs the same >>> calculation at the same speed but the additional thread is idling. >>> >>> In my understanding, both calculations should behave in the same way (i.e., >>> one working thread) for a program which is simply moving some data around >>> (mainly some MPI_BCAST and MPI_GATHER commands). >>> >>> I could observe this behaviour in OpenMPI 1.10.1 with ifort 16.0.1 and >>> gfortran 5.3.0. I could create a minimal working example, which is appended >>> to this mail. >>> >>> Am I missing something? >>> >>> Best regards, >>> Stefan >>> >>> - >>> >>> MWE: Compile this with "mpifort main.f90". When executing with "./a.out", >>> there is thread wasting cycles, while the master thread waits for input. >>> When executing with "mpirun -np 1 ./a.out" this thread is idling. >>> >>> program main >>> use mpi_f08 >>> implicit none >>> >>> integer :: ierror,rank >>> >>> call MPI_Init(ierror) >>>
Re: [OMPI users] Singleton process spawns additional thread
A singleton will indeed have an extra thread, but it should be quiescent. I’ll check the 1.10.2 release candidate and see if it still exhibits that behavior. > On Jan 7, 2016, at 9:32 PM, Au Eelis <auee...@gmail.com> wrote: > > Hi! > > It is in so far related, that one of these threads is actually doing > something. > > Btw, I noticed this on two separate machines! A computing cluster with > admin-built openmpi and Archlinux with openmpi from the repositories. > > However, running the code with openmpi 1.6.2 and ifort 13.0.0 does not show > this behaviour. > > Best regards, > Stefan > > > > On 01/07/2016 03:27 PM, Sasso, John (GE Power, Non-GE) wrote: >> Stefan, I don't know if this is related to your issue, but FYI... >> >> >>> Those are async progress threads - they block unless something requires >>> doing >>> >>> >>>> On Apr 15, 2015, at 8:36 AM, Sasso, John (GE Power & Water, Non-GE) >>>> <john1.sa...@ge.com> wrote: >>>> >>>> I stumbled upon something while using 'ps -eFL' to view threads of >>>> processes, and Google searches have failed to answer my question. This >>>> question holds for OpenMPI 1.6.x and even OpenMPI 1.4.x. >> >> >>>> For a program which is pure MPI (built and run using OpenMPI) and does not >>>> implement Pthreads or OpenMP, why is it that each MPI task appears as >>>> having 3 threads: >> >> >>>> UID PID PPID LWP C NLWPSZ RSS PSR STIME TTY TIME >>>> CMD >>>> sasso 20512 20493 20512 993 187849 582420 14 11:01 ? 00:26:37 >>>> /home/sasso/mpi_example.exe >>>> sasso 20512 20493 20588 03 187849 582420 11 11:01 ? 00:00:00 >>>> /home/sasso/mpi_example.exe >>>> sasso 20512 20493 20599 03 187849 582420 12 11:01 ? 00:00:00 >>>> /home/sasso/mpi_example.exe >> >> >>>> whereas if I compile and run a non-MPI program, 'ps -eFL' shows it running >>>> as a single thread? >>>> >>>> Granted the CPU utilization (C) for 2 of the 3 threads is zero, but the >>>> threads are bound to different processors (11,12,14). I am curious as to >>>> why this is, and no complaining that there is a problem. Thanks! >> >> >>>> --john >> >> >> -Original Message- >> From: users [mailto:users-boun...@open-mpi.org] On Behalf Of Au Eelis >> Sent: Thursday, January 07, 2016 7:10 AM >> To: us...@open-mpi.org >> Subject: [OMPI users] Singleton process spawns additional thread >> >> Hi! >> >> I have a weird problem with executing a singleton OpenMPI program, where an >> additional thread causes full load, while the master thread performs the >> actual calculations. >> >> In contrast, executing "mpirun -np 1 [executable]" performs the same >> calculation at the same speed but the additional thread is idling. >> >> In my understanding, both calculations should behave in the same way (i.e., >> one working thread) for a program which is simply moving some data around >> (mainly some MPI_BCAST and MPI_GATHER commands). >> >> I could observe this behaviour in OpenMPI 1.10.1 with ifort 16.0.1 and >> gfortran 5.3.0. I could create a minimal working example, which is appended >> to this mail. >> >> Am I missing something? >> >> Best regards, >> Stefan >> >> - >> >> MWE: Compile this with "mpifort main.f90". When executing with "./a.out", >> there is thread wasting cycles, while the master thread waits for input. >> When executing with "mpirun -np 1 ./a.out" this thread is idling. >> >> program main >> use mpi_f08 >> implicit none >> >> integer :: ierror,rank >> >> call MPI_Init(ierror) >> call MPI_Comm_Rank(MPI_Comm_World,rank,ierror) >> >> ! let master thread wait on [RETURN]-key >> if (rank == 0) then >> read(*,*) >> end if >> >> write(*,*) rank >> >> call mpi_barrier(mpi_comm_world, ierror) end program >> ___ >> users mailing list >> us...@open-mpi.org >> Subscription: >> https://urldefense.proofpoint.com/v2/url?u=http-3A__www.open-2Dmpi.org_mailman_listinfo.cgi_users=CwICAg=IV_clAzoPDE253xZdHuilRgztyh_RiV3wUrLrDQYWSI=tqKZ2vRCLufSSXPvzNxBrKr01YPimBPnb-JT-
Re: [OMPI users] Singleton process spawns additional thread
Hi! It is in so far related, that one of these threads is actually doing something. Btw, I noticed this on two separate machines! A computing cluster with admin-built openmpi and Archlinux with openmpi from the repositories. However, running the code with openmpi 1.6.2 and ifort 13.0.0 does not show this behaviour. Best regards, Stefan On 01/07/2016 03:27 PM, Sasso, John (GE Power, Non-GE) wrote: Stefan, I don't know if this is related to your issue, but FYI... Those are async progress threads - they block unless something requires doing On Apr 15, 2015, at 8:36 AM, Sasso, John (GE Power & Water, Non-GE) <john1.sa...@ge.com> wrote: I stumbled upon something while using 'ps -eFL' to view threads of processes, and Google searches have failed to answer my question. This question holds for OpenMPI 1.6.x and even OpenMPI 1.4.x. >> For a program which is pure MPI (built and run using OpenMPI) and does not implement Pthreads or OpenMP, why is it that each MPI task appears as having 3 threads: >> UID PID PPID LWP C NLWPSZ RSS PSR STIME TTY TIME CMD sasso 20512 20493 20512 993 187849 582420 14 11:01 ? 00:26:37 /home/sasso/mpi_example.exe sasso 20512 20493 20588 03 187849 582420 11 11:01 ? 00:00:00 /home/sasso/mpi_example.exe sasso 20512 20493 20599 03 187849 582420 12 11:01 ? 00:00:00 /home/sasso/mpi_example.exe >> whereas if I compile and run a non-MPI program, 'ps -eFL' shows it running as a single thread? Granted the CPU utilization (C) for 2 of the 3 threads is zero, but the threads are bound to different processors (11,12,14). I am curious as to why this is, and no complaining that there is a problem. Thanks! >> --john -Original Message- From: users [mailto:users-boun...@open-mpi.org] On Behalf Of Au Eelis Sent: Thursday, January 07, 2016 7:10 AM To: us...@open-mpi.org Subject: [OMPI users] Singleton process spawns additional thread Hi! I have a weird problem with executing a singleton OpenMPI program, where an additional thread causes full load, while the master thread performs the actual calculations. In contrast, executing "mpirun -np 1 [executable]" performs the same calculation at the same speed but the additional thread is idling. In my understanding, both calculations should behave in the same way (i.e., one working thread) for a program which is simply moving some data around (mainly some MPI_BCAST and MPI_GATHER commands). I could observe this behaviour in OpenMPI 1.10.1 with ifort 16.0.1 and gfortran 5.3.0. I could create a minimal working example, which is appended to this mail. Am I missing something? Best regards, Stefan - MWE: Compile this with "mpifort main.f90". When executing with "./a.out", there is thread wasting cycles, while the master thread waits for input. When executing with "mpirun -np 1 ./a.out" this thread is idling. program main use mpi_f08 implicit none integer :: ierror,rank call MPI_Init(ierror) call MPI_Comm_Rank(MPI_Comm_World,rank,ierror) ! let master thread wait on [RETURN]-key if (rank == 0) then read(*,*) end if write(*,*) rank call mpi_barrier(mpi_comm_world, ierror) end program ___ users mailing list us...@open-mpi.org Subscription: https://urldefense.proofpoint.com/v2/url?u=http-3A__www.open-2Dmpi.org_mailman_listinfo.cgi_users=CwICAg=IV_clAzoPDE253xZdHuilRgztyh_RiV3wUrLrDQYWSI=tqKZ2vRCLufSSXPvzNxBrKr01YPimBPnb-JT-Js0Fmk=NPeEHKik35WrcHGDl5ZRq4IC6Le5g03o5YoqD9InrHw=eRYTNaknio7tNJFdOMTqvdlNNIq9p6evJoQxuvmqrLs= Link to this post: https://urldefense.proofpoint.com/v2/url?u=http-3A__www.open-2Dmpi.org_community_lists_users_2016_01_28237.php=CwICAg=IV_clAzoPDE253xZdHuilRgztyh_RiV3wUrLrDQYWSI=tqKZ2vRCLufSSXPvzNxBrKr01YPimBPnb-JT-Js0Fmk=NPeEHKik35WrcHGDl5ZRq4IC6Le5g03o5YoqD9InrHw=2_axdls1JH4Wm5MlkOXRrtXFb2LLVLCleKVx4ybpltU= ___ users mailing list us...@open-mpi.org Subscription: http://www.open-mpi.org/mailman/listinfo.cgi/users Link to this post: http://www.open-mpi.org/community/lists/users/2016/01/28238.php
Re: [OMPI users] Singleton process spawns additional thread
Stefan, I don't know if this is related to your issue, but FYI... > Those are async progress threads - they block unless something requires doing > > >> On Apr 15, 2015, at 8:36 AM, Sasso, John (GE Power & Water, Non-GE) >> <john1.sa...@ge.com> wrote: >> >> I stumbled upon something while using 'ps -eFL' to view threads of >> processes, and Google searches have failed to answer my question. This >> question holds for OpenMPI 1.6.x and even OpenMPI 1.4.x. >> >> For a program which is pure MPI (built and run using OpenMPI) and does not >> implement Pthreads or OpenMP, why is it that each MPI task appears as having >> 3 threads: >> >> UID PID PPID LWP C NLWPSZ RSS PSR STIME TTY TIME CMD >> sasso 20512 20493 20512 993 187849 582420 14 11:01 ? 00:26:37 >> /home/sasso/mpi_example.exe >> sasso 20512 20493 20588 03 187849 582420 11 11:01 ? 00:00:00 >> /home/sasso/mpi_example.exe >> sasso 20512 20493 20599 03 187849 582420 12 11:01 ? 00:00:00 >> /home/sasso/mpi_example.exe >> >> whereas if I compile and run a non-MPI program, 'ps -eFL' shows it running >> as a single thread? >> >> Granted the CPU utilization (C) for 2 of the 3 threads is zero, but the >> threads are bound to different processors (11,12,14). I am curious as to >> why this is, and no complaining that there is a problem. Thanks! >> >> --john -----Original Message- From: users [mailto:users-boun...@open-mpi.org] On Behalf Of Au Eelis Sent: Thursday, January 07, 2016 7:10 AM To: us...@open-mpi.org Subject: [OMPI users] Singleton process spawns additional thread Hi! I have a weird problem with executing a singleton OpenMPI program, where an additional thread causes full load, while the master thread performs the actual calculations. In contrast, executing "mpirun -np 1 [executable]" performs the same calculation at the same speed but the additional thread is idling. In my understanding, both calculations should behave in the same way (i.e., one working thread) for a program which is simply moving some data around (mainly some MPI_BCAST and MPI_GATHER commands). I could observe this behaviour in OpenMPI 1.10.1 with ifort 16.0.1 and gfortran 5.3.0. I could create a minimal working example, which is appended to this mail. Am I missing something? Best regards, Stefan - MWE: Compile this with "mpifort main.f90". When executing with "./a.out", there is thread wasting cycles, while the master thread waits for input. When executing with "mpirun -np 1 ./a.out" this thread is idling. program main use mpi_f08 implicit none integer :: ierror,rank call MPI_Init(ierror) call MPI_Comm_Rank(MPI_Comm_World,rank,ierror) ! let master thread wait on [RETURN]-key if (rank == 0) then read(*,*) end if write(*,*) rank call mpi_barrier(mpi_comm_world, ierror) end program ___ users mailing list us...@open-mpi.org Subscription: https://urldefense.proofpoint.com/v2/url?u=http-3A__www.open-2Dmpi.org_mailman_listinfo.cgi_users=CwICAg=IV_clAzoPDE253xZdHuilRgztyh_RiV3wUrLrDQYWSI=tqKZ2vRCLufSSXPvzNxBrKr01YPimBPnb-JT-Js0Fmk=NPeEHKik35WrcHGDl5ZRq4IC6Le5g03o5YoqD9InrHw=eRYTNaknio7tNJFdOMTqvdlNNIq9p6evJoQxuvmqrLs= Link to this post: https://urldefense.proofpoint.com/v2/url?u=http-3A__www.open-2Dmpi.org_community_lists_users_2016_01_28237.php=CwICAg=IV_clAzoPDE253xZdHuilRgztyh_RiV3wUrLrDQYWSI=tqKZ2vRCLufSSXPvzNxBrKr01YPimBPnb-JT-Js0Fmk=NPeEHKik35WrcHGDl5ZRq4IC6Le5g03o5YoqD9InrHw=2_axdls1JH4Wm5MlkOXRrtXFb2LLVLCleKVx4ybpltU=
[OMPI users] Singleton process spawns additional thread
Hi! I have a weird problem with executing a singleton OpenMPI program, where an additional thread causes full load, while the master thread performs the actual calculations. In contrast, executing "mpirun -np 1 [executable]" performs the same calculation at the same speed but the additional thread is idling. In my understanding, both calculations should behave in the same way (i.e., one working thread) for a program which is simply moving some data around (mainly some MPI_BCAST and MPI_GATHER commands). I could observe this behaviour in OpenMPI 1.10.1 with ifort 16.0.1 and gfortran 5.3.0. I could create a minimal working example, which is appended to this mail. Am I missing something? Best regards, Stefan - MWE: Compile this with "mpifort main.f90". When executing with "./a.out", there is thread wasting cycles, while the master thread waits for input. When executing with "mpirun -np 1 ./a.out" this thread is idling. program main use mpi_f08 implicit none integer :: ierror,rank call MPI_Init(ierror) call MPI_Comm_Rank(MPI_Comm_World,rank,ierror) ! let master thread wait on [RETURN]-key if (rank == 0) then read(*,*) end if write(*,*) rank call mpi_barrier(mpi_comm_world, ierror) end program
