Good morning, I wanted to present an issue I am having with MPICH and validate whether this is a configuration problem, a limitation with MPICH, or a bug. I am writing an application which uses a large number of MPI windows, each window is given a relatively large amount of memory. This has never been a problem before, however we discovered if you allocate more than 2045 windows, you get an exception thrown. Notes: I am compiling using g++, version 4.8.5 on Red Hat Enterprise Linux version 7.2. My MPICH version is listed at the bottom of this email. It was installed via yum and is the RHEL default. I have attached sample output, to include the stdout/stderr. Also included is a Makefile and a simple example. The boundary of failure is between 2045 and 2046 windows. I have verified on my system this problem repeats even if I distribute windows between multiple communicators. I have not tested yet against ompi or mvapich. #-----------------------------------------------------------------------------------------------# #- Here is my output -# #-----------------------------------------------------------------------------------------------# mpirun -np 2 -hosts localhost ./mpi-win-test 2046 1 Initialized Rank: 0, Number Processors: 2, Hostname: test-machine Initialized Rank: 1, Number Processors: 2, Hostname: test-machine Fatal error in MPI_Win_create_dynamic: Other MPI error, error stack: MPI_Win_create_dynamic(154)..........: MPI_Win_create_dynamic(MPI_INFO_NULL, MPI_COMM_WORLD, win=0x10c1464) failed MPID_Win_create_dynamic(139).........: win_init(254)........................: MPIR_Comm_dup_impl(55)...............: MPIR_Comm_copy(1552).................: MPIR_Get_contextid(799)..............: MPIR_Get_contextid_sparse_group(1146): Cannot allocate context ID because of fragmentation (0/2048 free on this process; ignore_id=0) Fatal error in MPI_Win_create_dynamic: Other MPI error, error stack: MPI_Win_create_dynamic(154)..........: MPI_Win_create_dynamic(MPI_INFO_NULL, MPI_COMM_WORLD, win=0x19ef444) failed MPID_Win_create_dynamic(139).........: win_init(254)........................: MPIR_Comm_dup_impl(55)...............: MPIR_Comm_copy(1552).................: MPIR_Get_contextid(799)..............: MPIR_Get_contextid_sparse_group(1146): Cannot allocate context ID because of fragmentation (0/2048 free on this process; ignore_id=0) =================================================================================== = BAD TERMINATION OF ONE OF YOUR APPLICATION PROCESSES = EXIT CODE: 1 = CLEANING UP REMAINING PROCESSES = YOU CAN IGNORE THE BELOW CLEANUP MESSAGES =================================================================================== make: *** [run] Error 1 #------------------------------------------------------------------------------------------# #- Here is my Sample Makefile -# #------------------------------------------------------------------------------------------# # Path to mpich on RHEL7 MPI_INCL=-I/usr/include/mpich-x86_64 MPI_LIBS=-L/usr/lib64/mpich/lib -lmpich # C++11 Bindings (Being lazy with string) CXX_ARGS=-std=c++11 # Make th test all: mpi-win-test mpi-win-test: mpi-win-test.cpp g++ $< -o $@ $(MPI_INCL) $(MPI_LIBS) $(CXX_ARGS) # Args for application NUM_WINDOWS=2046 USE_DYNAMIC=1 # Sample run usage # # Args: # - Number of Windows # - Type of windows (1 dynamic, 0 static) run: mpirun -np 2 -hosts localhost ./mpi-win-test $(NUM_WINDOWS) $(USE_DYNAMIC) #------------------------------------------------------------------------------------------# #- Here is my Sample Application -# #------------------------------------------------------------------------------------------# #include <mpi.h> #include <iostream> #include <string> #include <vector> using namespace std; int main( int argc, char* argv[] ) { // Number of MPI Windows int num_windows = std::stoi(argv[1]); bool use_dynamic = std::stoi(argv[2]); // Initialize MPI MPI_Init( &argc, &argv ); // Get the rank and size int rank, nprocs; MPI_Comm_size( MPI_COMM_WORLD, &nprocs ); MPI_Comm_rank( MPI_COMM_WORLD, &rank ); // Get the processor name char hostname[MPI_MAX_PROCESSOR_NAME]; int hostname_len; MPI_Get_processor_name( hostname, &hostname_len); // Print Message for( int i=0; i<nprocs; i++ ){ MPI_Barrier(MPI_COMM_WORLD); if( i == rank ){ std::cout << "Initialized Rank: " << rank << ", Number Processors: " << nprocs << ", Hostname: " << hostname << std::endl; } } // MPI Variables vector<MPI_Aint> sdisp_remotes(num_windows); vector<MPI_Aint> sdisp_locals(num_windows); // Create MPI Windows vector<MPI_Win> windows(num_windows); int64_t buffer_size = 1000; char* buffer = new char[buffer_size]; for( int i=0; i<num_windows; i++ ) { if( use_dynamic ) { MPI_Win_create_dynamic( MPI_INFO_NULL, MPI_COMM_WORLD, &windows[i] ); } else { MPI_Win_create( &buffer, buffer_size, 1, MPI_INFO_NULL, MPI_COMM_WORLD, &windows[i] ); } } // Exception always occurs prior to reaching this point. // More Code Here that I am removing for brevity // Wait at the barrier MPI_Barrier( MPI_COMM_WORLD ); // Remove all windows for( int i=0; i<num_windows; i++) { // Destroy the MPI Window MPI_Win_free( &windows[i] ); } windows.clear(); // Clear buffer delete [] buffer; buffer = nullptr; // Close MPI MPI_Finalize(); return 0; } #--------------------------------------------------------------------------# #- MPICH Version Output -# #--------------------------------------------------------------------------# MPICH Version: 3.0.4 MPICH Release date: Wed Apr 24 10:08:10 CDT 2013 MPICH Device: ch3:nemesis MPICH configure: --build=x86_64-redhat-linux-gnu --host=x86_64-redhat-linux-gnu --program-prefix= --disable-dependency-tracking --prefix=/usr --exec-prefix=/usr --bindir=/usr/bin --sbindir=/usr/sbin --sysconfdir=/etc --datadir=/usr/share --includedir=/usr/include --libdir=/usr/lib64 --libexecdir=/usr/libexec --localstatedir=/var --sharedstatedir=/var/lib --mandir=/usr/share/man --infodir=/usr/share/info --enable-sharedlibs=gcc --enable-shared --enable-lib-depend --disable-rpath --enable-fc --with-device=ch3:nemesis --with-pm=hydra:gforker --sysconfdir=/etc/mpich-x86_64 --includedir=/usr/include/mpich-x86_64 --bindir=/usr/lib64/mpich/bin --libdir=/usr/lib64/mpich/lib --datadir=/usr/share/mpich --mandir=/usr/share/man/mpich --docdir=/usr/share/mpich/doc --htmldir=/usr/share/mpich/doc --with-hwloc-prefix=system FC=gfortran F77=gfortran CFLAGS=-m64 -O2 -g -pipe -Wall -Wp,-D_FORTIFY_SOURCE=2 -fexceptions -fstack-protector-strong --param=ssp-buffer-size=4 -grecord-gcc-switches -m64 -mtune=generic -fPIC CXXFLAGS=-m64 -O2 -g -pipe -Wall -Wp,-D_FORTIFY_SOURCE=2 -fexceptions -fstack-protector-strong --param=ssp-buffer-size=4 -grecord-gcc-switches -m64 -mtune=generic -fPIC FCFLAGS=-m64 -O2 -g -pipe -Wall -Wp,-D_FORTIFY_SOURCE=2 -fexceptions -fstack-protector-strong --param=ssp-buffer-size=4 -grecord-gcc-switches -m64 -mtune=generic -fPIC FFLAGS=-m64 -O2 -g -pipe -Wall -Wp,-D_FORTIFY_SOURCE=2 -fexceptions -fstack-protector-strong --param=ssp-buffer-size=4 -grecord-gcc-switches -m64 -mtune=generic -fPIC LDFLAGS=-Wl,-z,noexecstack MPICH2LIB_CFLAGS=-O2 -g -pipe -Wall -Wp,-D_FORTIFY_SOURCE=2 -fexceptions -fstack-protector-strong --param=ssp-buffer-size=4 -grecord-gcc-switches -m64 -mtune=generic MPICH2LIB_CXXFLAGS=-O2 -g -pipe -Wall -Wp,-D_FORTIFY_SOURCE=2 -fexceptions -fstack-protector-strong --param=ssp-buffer-size=4 -grecord-gcc-switches -m64 -mtune=generic MPICH2LIB_FCFLAGS=-O2 -g -pipe -Wall -Wp,-D_FORTIFY_SOURCE=2 -fexceptions -fstack-protector-strong --param=ssp-buffer-size=4 -grecord-gcc-switches -m64 -mtune=generic MPICH2LIB_FFLAGS=-O2 -g -pipe -Wall -Wp,-D_FORTIFY_SOURCE=2 -fexceptions -fstack-protector-strong --param=ssp-buffer-size=4 -grecord-gcc-switches -m64 -mtune=generic MPICH CC: cc -m64 -O2 -g -pipe -Wall -Wp,-D_FORTIFY_SOURCE=2 -fexceptions -fstack-protector-strong --param=ssp-buffer-size=4 -grecord-gcc-switches -m64 -mtune=generic -fPIC -O2 MPICH CXX: c++ -m64 -O2 -g -pipe -Wall -Wp,-D_FORTIFY_SOURCE=2 -fexceptions -fstack-protector-strong --param=ssp-buffer-size=4 -grecord-gcc-switches -m64 -mtune=generic -fPIC -O2 MPICH F77: gfortran -m64 -O2 -g -pipe -Wall -Wp,-D_FORTIFY_SOURCE=2 -fexceptions -fstack-protector-strong --param=ssp-buffer-size=4 -grecord-gcc-switches -m64 -mtune=generic -fPIC -O2 MPICH FC: gfortran -m64 -O2 -g -pipe -Wall -Wp,-D_FORTIFY_SOURCE=2 -fexceptions -fstack-protector-strong --param=ssp-buffer-size=4 -grecord-gcc-switches -m64 -mtune=generic -fPIC -O2 CONFIDENTIALITY NOTICE - SNC EMAIL: This email and any attachments are confidential, may contain proprietary, protected, or export controlled information, and are intended for the use of the intended recipients only. 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