9 is defined as SIGKILL (see the signal(7) manual page), so I suspect that you are doing this on a 32-bit Linux system and maybe the OOM-killer is running in - you can check this on dmesg output or reading /var/log/system or /var/log/messages .
To deal with this, try playing with the core.packedGitWindowSize and core.packedGitLimit configuration variables .
source share