Did you set the GOMAXPROCS environment variable? // By default, Go keeps only one kernel thread (m) running user code // at a single time; other threads ma

Did you set the GOMAXPROCS environment variable? // By default, Go keeps only one kernel thread (m) running user code // at a single time; other threads may be blocked in the operating system. // Setting the environment variable $GOMAXPROCS or calling // runtime.GOMAXPROCS() will change the number of user threads // allowed to execute simultaneously. $GOMAXPROCS is thus an // approximation of the maximum number of cores to use. From http://golang.org/src/pkg/runtime/proc.c http://golang.org/src/pkg/runtime/proc.c