Hi, everyone! This bug was observed in 2022.07.05, using boost version 1.79.0. Similar behaviour was commented on before on online messageboards. Bug description When starting a new, detached process with Process.Spawn in a posix system, if the parent process outlives the child, the child process remains in zombie state for the parent process' lifetime. The bug described above is demonstrated in the CMake project attached to this document. Analysis The spawn function injects the syscall "signal(SIGCHLD, SIG_IGN)" with a functor of type boost::process::detail::posix::sig_init_. This is done to the forked child process, to no avail. And this is not done (and should not be done) in the parent process being too intrusive. Possible mitigation Introducing an in-between forked process that serves as the parent of the to-be-spawned process with SIGCHLD set to SIG_IGN would prevent the spawned process to become zombie, and simultaneously does not disturb the parent process' signal handlers. Introducing another class alternative to sig_init_ with the functionality described above would be a reasonable approach. An implementation sketch of the double fork method can be found in the attached project. System used OS: Ubuntu 18.04.6 LTS arch: x86_64 compiler: gcc-7.5.0 libc: libc-2.27 boost: 1.79.0 (built from source) Best regards, Benedek Tass