Hi, I'm working with mpich 3.0.4 and I get a segfault in Hydra when I try to run an application on a large number of processes (8192). I simply run the following command: mpirun -f ~/machine_list -n 8192 my_exec_file I tried to run mpirun in valgrind to identify the problem and here is the output: Invalid read of size 1 ==44266== at 0x4A077F2: __GI_strlen (mc_replace_strmem.c:284) ==44266== by 0x3D774802B5: strdup (in /lib64/libc-2.12.so) ==44266== by 0x40EBA5: HYD_pmcd_pmi_fill_in_exec_launch_info (pmiserv_utils.\ c:375) ==44266== by 0x40A5C2: HYD_pmci_launch_procs (pmiserv_pmci.c:121) ==44266== by 0x403A1E: main (mpiexec.c:326) ==44266== Address 0x0 is not stack'd, malloc'd or (recently) free'd If I try to run on a smaller number of processes (eg 512), everything works fine. Any suggestion to solve the problem? Thomas