Modules/resource.c

Source:

cpython 3.14 @ ab2d84fe1023/Modules/resource.c ↗

resource wraps the POSIX getrlimit(2), setrlimit(2), and getrusage(2) system calls. It provides constants like RLIMIT_CPU, RLIMIT_NOFILE, and RLIMIT_AS and the struct_rusage named tuple.

Map

Lines	Symbol	Role
1-60	Module constants	RLIMIT_*, RUSAGE_*, RLIM_INFINITY
61-150	resource_getrlimit_impl	Return (soft, hard) tuple for a resource
151-220	resource_setrlimit_impl	Set (soft, hard) limits
221-300	resource_getrusage_impl	Return struct_rusage for self or children
301-350	struct_rusage	structseq with ru_utime, ru_stime, ru_maxrss, etc.

Reading

getrlimit

// CPython: Modules/resource.c:98 resource_getrlimit_impl
static PyObject *
resource_getrlimit_impl(PyObject *module, int resource)
{
    struct rlimit rl;
    if (getrlimit(resource, &rl)) {
        PyErr_SetFromErrno(PyExc_OSError);
        return NULL;
    }
    return Py_BuildValue("NN",
        PyLong_FromRlim_t(rl.rlim_cur),   /* soft limit */
        PyLong_FromRlim_t(rl.rlim_hard));  /* hard limit */
}

RLIM_INFINITY is returned as resource.RLIM_INFINITY (a very large int).

setrlimit

// CPython: Modules/resource.c:160 resource_setrlimit_impl
static PyObject *
resource_setrlimit_impl(PyObject *module, int resource, PyObject *limits)
{
    struct rlimit rl;
    if (!PyArg_ParseTuple(limits, "O&O&",
                          rlim_t_converter, &rl.rlim_cur,
                          rlim_t_converter, &rl.rlim_hard))
        return NULL;
    if (setrlimit(resource, &rl)) {
        if (errno == EINVAL)
            PyErr_SetString(PyExc_ValueError,
                "current limit exceeds maximum limit");
        else if (errno == EPERM)
            PyErr_SetString(PyExc_ValueError,
                "not allowed to raise maximum limit");
        else
            PyErr_SetFromErrno(PyExc_OSError);
        return NULL;
    }
    Py_RETURN_NONE;
}

getrusage

// CPython: Modules/resource.c:240 resource_getrusage_impl
static PyObject *
resource_getrusage_impl(PyObject *module, int who)
{
    /* who: RUSAGE_SELF (0), RUSAGE_CHILDREN (-1), RUSAGE_THREAD (1) */
    struct rusage ru;
    if (getrusage(who, &ru)) {
        PyErr_SetFromErrno(PyExc_OSError);
        return NULL;
    }
    return fill_rusage(&ru);   /* populate struct_rusage structseq */
}

struct_rusage fields

// CPython: Modules/resource.c:280 struct_rusage_fields
/* ru_utime   — user time (float seconds) */
/* ru_stime   — system time (float seconds) */
/* ru_maxrss  — maximum resident set size (bytes on Linux, kilobytes on macOS) */
/* ru_ixrss   — shared memory size (not maintained on Linux) */
/* ru_idrss   — unshared data size */
/* ru_isrss   — unshared stack size */
/* ru_minflt  — soft page faults */
/* ru_majflt  — hard page faults */
/* ru_nswap   — swaps */
/* ru_inblock — block input operations */
/* ru_oublock — block output operations */
/* ru_msgsnd  — IPC messages sent */
/* ru_msgrcv  — IPC messages received */
/* ru_nsignals — signals received */
/* ru_nvcsw   — voluntary context switches */
/* ru_nivcsw  — involuntary context switches */

gopy notes

resource is in module/resource/module.go. getrlimit/setrlimit use syscall.Getrlimit/syscall.Setrlimit. getrusage uses syscall.Getrusage. struct_rusage is a structseq defined via objects.NewStructSeqType. RLIM_INFINITY is syscall.RLIM_INFINITY cast to a Python int.