Since they are simply normal RPC messages, the keep alive packets are
subject to the "max_client_requests" limit just like any API calls.
Thus, if a client hits the 'max_client_requests' limit and all the
pending API calls take a long time to complete, it may result in
keep-alives firing and dropping the client connection.
This has been seen by a number of users with the default value of
max_client_requests=5, by issuing 5 concurrent live migration
operations.
By printing a warning message when this happens, admins will be alerted
to the fact that their active clients are exceeding the default client
requests limit.
Signed-off-by: Daniel P. Berrangé <berra...@redhat.com>
---
In v2:
- now only warn once per client to avoid log spam
src/rpc/virnetserverclient.c | 8 ++++++++
1 file changed, 8 insertions(+)
diff --git a/src/rpc/virnetserverclient.c b/src/rpc/virnetserverclient.c
index 30f6af7be5..c9a4eb521e 100644
--- a/src/rpc/virnetserverclient.c
+++ b/src/rpc/virnetserverclient.c
@@ -93,6 +93,9 @@ struct _virNetServerClient
* throttling calculations */
size_t nrequests;
size_t nrequests_max;
+ /* True if we've warned about nrequests hittin
+ * the server limit already */
+ bool nrequests_warning;
/* Zero or one messages being received. Zero if
* nrequests >= max_clients and throttling */
virNetMessage *rx;
@@ -1261,6 +1264,11 @@ static virNetMessage
*virNetServerClientDispatchRead(virNetServerClient *client)
client->rx->buffer = g_new0(char, client->rx->bufferLength);
client->nrequests++;
}
+ } else if (!client->nrequests_warning) {
+ client->nrequests_warning = true;
+ VIR_WARN("Client hit max requests limit %zd. This may result "
+ "in keep-alive timeouts. Consider tuning the "
+ "max_client_requests server parameter",
client->nrequests);
}
virNetServerClientUpdateEvent(client);
--
2.37.3
