Hi, using mpich 3.1 I notice that my application leaks memory. Compiling it with '-O1 -g -fno-omit-frame-pointer -fsanitize=leak' using gcc 4.9 it appears the sources is comparing communicators, for example: [0] Direct leak of 38400 byte(s) in 600 object(s) allocated from: [0] #0 0x7f84298d53a8 in __interceptor_malloc ../../../../gcc/libsanitizer/lsan/lsan_interceptors.cc:66 [0] #1 0x7f842aabaf6b in MPIR_Group_create /data/vjoost/mpich-3.1/src/mpi/group/grouputil.c:77 [0] #2 0x7f842ab88314 in MPIR_Comm_group_impl /data/vjoost/mpich-3.1/src/mpi/comm/comm_group.c:44 [0] #3 0x7f842ab840d3 in PMPI_Comm_compare /data/vjoost/mpich-3.1/src/mpi/comm/comm_compare.c:122 [0] #4 0x7f842aac8e84 in pmpi_comm_compare_ /data/vjoost/mpich-3.1/src/binding/f77/comm_comparef.c:267 [0] #5 0x1bfd447 in __message_passing_MOD_mp_comm_compare /data/vjoost/clean/cp2k/cp2k/src/common/message_passing.F:1084 I'm not seeing other leaks, so is guess something particular is going on here. Any suggestions on a possible fix ? Thanks, Joost