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Implement port/file-descriptor exhaustion metric.

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This uses a heuristic that came up after a discussion with David.

I'm leaving this as a separate commit so that it can be discussed further if
needed.
This commit is contained in:
George Kadianakis 2021-03-09 15:40:00 +02:00
parent f493a12e89
commit faf1fe833e
1 changed files with 30 additions and 8 deletions
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38
src/core/mainloop/connection.c
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@ -1239,12 +1239,34 @@ create_unix_sockaddr(const char *listenaddress, char **readable_address,
}
#endif /* defined(HAVE_SYS_UN_H) || defined(RUNNING_DOXYGEN) */
/** Warn that an accept or a connect has failed because we're running out of
* TCP sockets we can use on current system. Rate-limit these warnings so
* that we don't spam the log. */
/**
* A socket failed from resource exhaustion.
*
* AMong other actions, warn that an accept or a connect has failed because
* we're running out of TCP sockets we can use on current system. Rate-limit
* these warnings so that we don't spam the log. */
static void
warn_too_many_conns(void)
socket_failed_from_resource_exhaustion(void)
{
/* When we get to this point we know that a socket could not be
* established. However the kernel does not let us know whether the reason is
* because we ran out of TCP source ports, or because we exhausted all the
* FDs on this system, or for any other reason.
*
* For this reason, we are going to use the following heuristic: If our
* system supports a lot of sockets, we will assume that it's a problem of
* TCP port exhaustion. Otherwise, if our system does not support many
* sockets, we will assume that this is because of file descriptor
* exhaustion.
*/
if (get_max_sockets() > 65535) {
/* TCP port exhaustion */
rep_hist_note_overload(OVERLOAD_GENERAL);
} else {
/* File descriptor exhaustion */
rep_hist_note_overload(OVERLOAD_FD_EXHAUSTED);
}
#define WARN_TOO_MANY_CONNS_INTERVAL (6*60*60)
static ratelim_t last_warned = RATELIM_INIT(WARN_TOO_MANY_CONNS_INTERVAL);
char *m;
@ -1473,7 +1495,7 @@ connection_listener_new(const struct sockaddr *listensockaddr,
if (!SOCKET_OK(s)) {
int e = tor_socket_errno(s);
if (ERRNO_IS_RESOURCE_LIMIT(e)) {
warn_too_many_conns();
socket_failed_from_resource_exhaustion();
/*
* We'll call the OOS handler at the error exit, so set the
* exhaustion flag for it.
@ -1599,7 +1621,7 @@ connection_listener_new(const struct sockaddr *listensockaddr,
if (! SOCKET_OK(s)) {
int e = tor_socket_errno(s);
if (ERRNO_IS_RESOURCE_LIMIT(e)) {
warn_too_many_conns();
socket_failed_from_resource_exhaustion();
/*
* We'll call the OOS handler at the error exit, so set the
* exhaustion flag for it.
@ -1912,7 +1934,7 @@ connection_handle_listener_read(connection_t *conn, int new_type)
connection_check_oos(get_n_open_sockets(), 0);
return 0;
} else if (ERRNO_IS_RESOURCE_LIMIT(e)) {
warn_too_many_conns();
socket_failed_from_resource_exhaustion();
/* Exhaustion; tell the OOS handler */
connection_check_oos(get_n_open_sockets(), 1);
return 0;
@ -2175,7 +2197,7 @@ connection_connect_sockaddr,(connection_t *conn,
*/
*socket_error = tor_socket_errno(s);
if (ERRNO_IS_RESOURCE_LIMIT(*socket_error)) {
warn_too_many_conns();
socket_failed_from_resource_exhaustion();
connection_check_oos(get_n_open_sockets(), 1);
} else {
log_warn(LD_NET,"Error creating network socket: %s",