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gh-102494: fix MemoryError when using selectors on Solaris #102495

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gh-102494: fix MemoryError when using selectors on Solaris #102495

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979dd2b
gh-102494: fix MemoryError when using selectors on Solaris
kulikjak Mar 7, 2023
7db3a64
📜🤖 Added by blurb_it.
blurb-it[bot] Mar 7, 2023
f949dea
split the in and out buffer into two with different sizes
kulikjak Jul 30, 2025
8610053
remove the old blurb
kulikjak Jul 30, 2025
adf2e6f
minor fix
kulikjak Jul 30, 2025
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split the in and out buffer into two with different sizes
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@kulikjak
kulikjak committed Jul 30, 2025
commit f949dea21f419f431f196796925a1231a1c0e697
49 changes: 32 additions & 17 deletions Modules/selectmodule.c
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Original file line number Diff line number Diff line change
Expand Up @@ -790,12 +790,16 @@ poll_dealloc(PyObject *op)
#ifdef HAVE_SYS_DEVPOLL_H
static PyMethodDef devpoll_methods[];

#define DEVPOLL_IN_BUFFER_SIZE 128
#define DEVPOLL_MAX_OUT_BUFFER_SIZE 1024

typedef struct {
PyObject_HEAD
int fd_devpoll;
int max_n_fds;
int n_fds;
int out_size;
struct pollfd *fds;
struct pollfd *out_fds;
} devpollObject;

#define devpollObject_CAST(op) ((devpollObject *)(op))
Expand Down Expand Up @@ -848,7 +852,7 @@ internal_devpoll_register(devpollObject *self, int fd,
self->fds[self->n_fds].fd = fd;
self->fds[self->n_fds].events = POLLREMOVE;

if (++self->n_fds == self->max_n_fds) {
if (++self->n_fds == DEVPOLL_IN_BUFFER_SIZE) {
if (devpoll_flush(self))
return NULL;
}
Expand All @@ -857,7 +861,7 @@ internal_devpoll_register(devpollObject *self, int fd,
self->fds[self->n_fds].fd = fd;
self->fds[self->n_fds].events = (signed short)events;

if (++self->n_fds == self->max_n_fds) {
if (++self->n_fds == DEVPOLL_IN_BUFFER_SIZE) {
if (devpoll_flush(self))
return NULL;
}
Expand Down Expand Up @@ -929,7 +933,7 @@ select_devpoll_unregister_impl(devpollObject *self, int fd)
self->fds[self->n_fds].fd = fd;
self->fds[self->n_fds].events = POLLREMOVE;

if (++self->n_fds == self->max_n_fds) {
if (++self->n_fds == DEVPOLL_IN_BUFFER_SIZE) {
if (devpoll_flush(self))
return NULL;
}
Expand Down Expand Up @@ -989,8 +993,8 @@ select_devpoll_poll_impl(devpollObject *self, PyObject *timeout_obj)
if (devpoll_flush(self))
return NULL;

dvp.dp_fds = self->fds;
dvp.dp_nfds = self->max_n_fds;
dvp.dp_fds = self->out_fds;
dvp.dp_nfds = self->out_size;
dvp.dp_timeout = (int)ms;

if (timeout >= 0) {
Expand Down Expand Up @@ -1034,8 +1038,8 @@ select_devpoll_poll_impl(devpollObject *self, PyObject *timeout_obj)
return NULL;

for (i = 0; i < poll_result; i++) {
num1 = PyLong_FromLong(self->fds[i].fd);
num2 = PyLong_FromLong(self->fds[i].revents);
num1 = PyLong_FromLong(self->out_fds[i].fd);
num2 = PyLong_FromLong(self->out_fds[i].revents);
if ((num1 == NULL) || (num2 == NULL)) {
Py_XDECREF(num1);
Py_XDECREF(num2);
Expand Down Expand Up @@ -1128,8 +1132,8 @@ static devpollObject *
newDevPollObject(PyObject *module)
{
devpollObject *self;
int fd_devpoll, limit_result;
struct pollfd *fds;
int fd_devpoll, limit_result, out_size;
struct pollfd *fds, *out_fds;
struct rlimit limit;

/*
Expand All @@ -1145,35 +1149,45 @@ newDevPollObject(PyObject *module)
}

/*
** If the limit is too high (or RLIM_INFINITY), we might allocate huge
** amounts of memory (or even fail to allocate). Because of that, we limit
** the number of allocated structs to 2^18 (which is ~4MB of memory).
** If the limit is too high (or RLIM_INFINITY), we might
** allocate huge amounts of memory or even fail to allocate.
*/
if (limit.rlim_cur > (rlim_t)262144) {
limit.rlim_cur = (rlim_t)262144;
out_size = limit.rlim_cur;
if (out_size > DEVPOLL_MAX_OUT_BUFFER_SIZE) {
out_size = DEVPOLL_MAX_OUT_BUFFER_SIZE;
}

fd_devpoll = _Py_open("/dev/poll", O_RDWR);
if (fd_devpoll == -1)
return NULL;

fds = PyMem_NEW(struct pollfd, limit.rlim_cur);
fds = PyMem_NEW(struct pollfd, DEVPOLL_IN_BUFFER_SIZE);
if (fds == NULL) {
close(fd_devpoll);
PyErr_NoMemory();
return NULL;
}

out_fds = PyMem_NEW(struct pollfd, out_size);
if (fds == NULL) {
close(fd_devpoll);
PyMem_Free(fds);
PyErr_NoMemory();
return NULL;
}

self = PyObject_New(devpollObject, get_select_state(module)->devpoll_Type);
if (self == NULL) {
close(fd_devpoll);
PyMem_Free(fds);
PyMem_Free(out_fds);
return NULL;
}
self->fd_devpoll = fd_devpoll;
self->max_n_fds = limit.rlim_cur;
self->max_n_fds = out_size;
self->n_fds = 0;
self->fds = fds;
self->out_fds = out_fds;

return self;
}
Expand All @@ -1185,6 +1199,7 @@ devpoll_dealloc(PyObject *op)
PyTypeObject *type = Py_TYPE(self);
(void)devpoll_internal_close(self);
PyMem_Free(self->fds);
PyMem_Free(self->out_fds);
PyObject_Free(self);
Py_DECREF(type);
}
Expand Down
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