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- commit f87ea7d2fdcfa3ccd5d605b3ce96642d28f20f6b
- Author: Willy Tarreau <w@1wt.eu>
- Date: Fri Aug 24 14:31:53 2018 +0200
-
- BUG/MEDIUM: unix: provide a ->drain() function
-
- Right now conn_sock_drain() calls the protocol's ->drain() function if
- it exists, otherwise it simply tries to disable polling for receiving
- on the connection. This doesn't work well anymore since we've implemented
- the muxes in 1.8, and it has a side effect with keep-alive backend
- connections established over unix sockets. What happens is that if
- during the idle time after a request, a connection reports some data,
- si_idle_conn_null_cb() is called, which will call conn_sock_drain().
- This one sees there's no drain() on unix sockets and will simply disable
- polling for data on the connection. But it doesn't do anything on the
- conn_stream. Thus while leaving the conn_fd_handler, the mux's polling
- is updated and recomputed based on the conn_stream's polling state,
- which is still enabled, and nothing changes, so we see the process
- use 100% CPU in this case because the FD remains active in the cache.
-
- There are several issues that need to be addressed here. The first and
- most important is that we cannot expect some protocols to simply stop
- reading data when asked to drain pending data. So this patch make the
- unix sockets rely on tcp_drain() since the functions are the same. This
- solution is appropriate for backporting, but a better one is desired for
- the long term. The second issue is that si_idle_conn_null_cb() shouldn't
- drain the connection but the conn_stream.
-
- At the moment we don't have any way to drain a conn_stream, though a flag
- on rcv_buf() will do it well. Until we support muxes on the server side
- it is not a problem so this part can be addressed later.
-
- This fix must be backported to 1.8.
-
- (cherry picked from commit fe5d2ac65fd58a8320e8dc725219c1bce5839592)
- Signed-off-by: Willy Tarreau <w@1wt.eu>
-
- diff --git a/src/proto_uxst.c b/src/proto_uxst.c
- index f2374be6..0b3a57b8 100644
- --- a/src/proto_uxst.c
- +++ b/src/proto_uxst.c
- @@ -42,6 +42,7 @@
- #include <proto/listener.h>
- #include <proto/log.h>
- #include <proto/protocol.h>
- +#include <proto/proto_tcp.h>
- #include <proto/task.h>
-
- static int uxst_bind_listener(struct listener *listener, char *errmsg, int errlen);
- @@ -71,6 +72,7 @@ static struct protocol proto_unix = {
- .disable_all = disable_all_listeners,
- .get_src = uxst_get_src,
- .get_dst = uxst_get_dst,
- + .drain = tcp_drain,
- .pause = uxst_pause_listener,
- .add = uxst_add_listener,
- .listeners = LIST_HEAD_INIT(proto_unix.listeners),
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