Você poderia descrever como esse processo é iniciado e nos fornecer a saída de ulimit -a
de um contexto o mais próximo possível?
Como pthread_create(3)
explica, você está se deparando com:
ERRORS
EAGAIN Insufficient resources to create another thread, or a system-
imposed limit on the number of threads was encountered. The
latter case may occur in two ways: the RLIMIT_NPROC soft
resource limit (set via setrlimit(2)), which limits the number
of process for a real user ID, was reached; or the kernel's
system-wide limit on the number of threads, /proc/sys/ker‐
nel/threads-max, was reached.