[PATCH 0/3] iproto: allow to configure IPROTO_MSG_MAX

[PATCH 0/3] iproto: allow to configure IPROTO_MSG_MAX

[Vladislav Shpilevoy]

Branch: http://github.com/tarantool/tarantool/tree/gh-3320-config-msg-max
Issue: https://github.com/tarantool/tarantool/issues/3320

IPROTO_MSG_MAX is a constant that restricts count of requests in fly. It allows
to do not produce too many fibers in TX thread, that would lead to too big
overhead on fibers switching, their stack storing.

But some users have powerful metal on which Tarantool IPROTO_MSG_MAX constant is
not serious. The patch exposes it as a configuration runtime parameter.

'iproto_msg_max' is its name. If a user sees that IProto thread is stuck due to
too many requests, it can change iproto_msg_max in runtime, and IProto thread
immediately starts processing pending requests.

'iproto_msg_max' can be decreased, but obviously it can not stop already runned
requests, so if now in IProto thread request count is > new 'iproto_msg_max'
value, then it takes some time until some requests will be finished.

In the same patchset a bug is fixed with incorrect discarding long-poll requests
input. Discard just calls iproto_resume() trying to notify libev, that is can
get new data. But is makes no sense, because iproto_resume() continues only
connections stopped due to reached limit of maximal requests in fly, but not
connections whose buffer is overflowed. Such stopped connections can be
continued only after a request is complete.

To continue read from the connection whose buffer was freed by discarding
long-poll it is necessary to explicitly feed to it EV_READ event. On this event iproto_connection_on_input will read a blocked data if it exists.

Vladislav Shpilevoy (3):
  iproto: rename iproto_bind_msg to iproto_cfg_msg
  iproto: fix error with input discarding
  iproto: allow to configure IPROTO_MSG_MAX

 src/box/box.cc                  |   7 ++
 src/box/box.h                   |   1 +
 src/box/iproto.cc               |  79 ++++++++++----
 src/box/iproto.h                |   3 +
 src/box/lua/cfg.cc              |  12 +++
 src/box/lua/load_cfg.lua        |   3 +
 test/app-tap/init_script.result |  73 ++++++-------
 test/box/admin.result           |   2 +
 test/box/cfg.result             |  24 +++++
 test/box/cfg.test.lua           |   9 ++
 test/box/request_limit.result   | 229 ++++++++++++++++++++++++++++++++++++++++
 test/box/request_limit.test.lua | 114 ++++++++++++++++++++
 12 files changed, 500 insertions(+), 56 deletions(-)
 create mode 100644 test/box/request_limit.result
 create mode 100644 test/box/request_limit.test.lua

-- 
2.15.1 (Apple Git-101)

[PATCH 1/3] iproto: rename iproto_bind_msg to iproto_cfg_msg

[Vladislav Shpilevoy]

IProto_bind_msg is used by TX thread to udpate bind address in
IProto thread with no explicit locking anything.

In #3320 new IProto dynamic configuration parameter appears -
'iproto_msg_max' which regulates how many IProto requests can be
in fly.

The idea is to reuse iproto_bind_msg for this.

Part of #3320
---
 src/box/iproto.cc | 10 +++++-----
 1 file changed, 5 insertions(+), 5 deletions(-)

diff --git a/src/box/iproto.cc b/src/box/iproto.cc
index 37026984d..fe502b51b 100644
--- a/src/box/iproto.cc
+++ b/src/box/iproto.cc
@@ -1659,15 +1659,15 @@ iproto_init()
  * we need to bounce a couple of messages to and
  * from this thread.
  */
-struct iproto_bind_msg: public cbus_call_msg
+struct iproto_cfg_msg: public cbus_call_msg
 {
 	const char *uri;
 };
 
 static int
-iproto_do_bind(struct cbus_call_msg *m)
+iproto_do_cfg(struct cbus_call_msg *m)
 {
-	const char *uri  = ((struct iproto_bind_msg *) m)->uri;
+	const char *uri  = ((struct iproto_cfg_msg *) m)->uri;
 	try {
 		if (evio_service_is_active(&binary))
 			evio_service_stop(&binary);
@@ -1695,9 +1695,9 @@ iproto_do_listen(struct cbus_call_msg *m)
 void
 iproto_bind(const char *uri)
 {
-	static struct iproto_bind_msg m;
+	static struct iproto_cfg_msg m;
 	m.uri = uri;
-	if (cbus_call(&net_pipe, &tx_pipe, &m, iproto_do_bind,
+	if (cbus_call(&net_pipe, &tx_pipe, &m, iproto_do_cfg,
 		      NULL, TIMEOUT_INFINITY))
 		diag_raise();
 }
-- 
2.15.1 (Apple Git-101)

Re: [PATCH 1/3] iproto: rename iproto_bind_msg to iproto_cfg_msg

[Vladimir Davydov]

On Sat, Apr 21, 2018 at 01:52:09AM +0300, Vladislav Shpilevoy wrote:
> IProto_bind_msg is used by TX thread to udpate bind address in
> IProto thread with no explicit locking anything.
> 
> In #3320 new IProto dynamic configuration parameter appears -
> 'iproto_msg_max' which regulates how many IProto requests can be
> in fly.
> 
> The idea is to reuse iproto_bind_msg for this.
> 
> Part of #3320
> ---
>  src/box/iproto.cc | 10 +++++-----
>  1 file changed, 5 insertions(+), 5 deletions(-)

I don't see any point in this patch. Patch 3 overwrites half of it
anyway so it doesn't really facilitate review. Please squash it.

> 
> diff --git a/src/box/iproto.cc b/src/box/iproto.cc
> index 37026984d..fe502b51b 100644
> --- a/src/box/iproto.cc
> +++ b/src/box/iproto.cc
> @@ -1659,15 +1659,15 @@ iproto_init()
>   * we need to bounce a couple of messages to and
>   * from this thread.
>   */
> -struct iproto_bind_msg: public cbus_call_msg
> +struct iproto_cfg_msg: public cbus_call_msg
>  {
>  	const char *uri;
>  };
>  
>  static int
> -iproto_do_bind(struct cbus_call_msg *m)
> +iproto_do_cfg(struct cbus_call_msg *m)
>  {
> -	const char *uri  = ((struct iproto_bind_msg *) m)->uri;
> +	const char *uri  = ((struct iproto_cfg_msg *) m)->uri;
>  	try {
>  		if (evio_service_is_active(&binary))
>  			evio_service_stop(&binary);
> @@ -1695,9 +1695,9 @@ iproto_do_listen(struct cbus_call_msg *m)
>  void
>  iproto_bind(const char *uri)
>  {
> -	static struct iproto_bind_msg m;
> +	static struct iproto_cfg_msg m;
>  	m.uri = uri;
> -	if (cbus_call(&net_pipe, &tx_pipe, &m, iproto_do_bind,
> +	if (cbus_call(&net_pipe, &tx_pipe, &m, iproto_do_cfg,
>  		      NULL, TIMEOUT_INFINITY))
>  		diag_raise();
>  }

Re: [tarantool-patches] Re: [PATCH 1/3] iproto: rename iproto_bind_msg to iproto_cfg_msg

[Vladislav Shpilevoy]

Hello. Thanks for review!

On 23/04/2018 14:22, Vladimir Davydov wrote:
> On Sat, Apr 21, 2018 at 01:52:09AM +0300, Vladislav Shpilevoy wrote:
>> IProto_bind_msg is used by TX thread to udpate bind address in
>> IProto thread with no explicit locking anything.
>>
>> In #3320 new IProto dynamic configuration parameter appears -
>> 'iproto_msg_max' which regulates how many IProto requests can be
>> in fly.
>>
>> The idea is to reuse iproto_bind_msg for this.
>>
>> Part of #3320
>> ---
>>   src/box/iproto.cc | 10 +++++-----
>>   1 file changed, 5 insertions(+), 5 deletions(-)
> 
> I don't see any point in this patch. Patch 3 overwrites half of it
> anyway so it doesn't really facilitate review. Please squash it.
> 

Done.

[PATCH 2/3] iproto: fix error with input discarding

[Vladislav Shpilevoy]

Long-polling request has a feature allowing to discard an input
buffer in a connection before the main request is finished.

Before the patch discard just calls iproto_resume() trying to
notify libev, that is can get new data. But is makes no sense,
because iproto_resume() continues only connections stopped due
to reached limit of maximal requests in fly, but not connections
whose buffer is overflowed. Such stopped connections can be
continued only after a request is complete.

To continue read from the connection whose buffer was freed by
discarding long-poll it is necessary to explicitly feed to it
EV_READ event. On this event iproto_connection_on_input will read
a blocked data if it exists.
---
 src/box/iproto.cc               |   5 +-
 test/box/request_limit.result   | 114 ++++++++++++++++++++++++++++++++++++++++
 test/box/request_limit.test.lua |  63 ++++++++++++++++++++++
 3 files changed, 180 insertions(+), 2 deletions(-)
 create mode 100644 test/box/request_limit.result
 create mode 100644 test/box/request_limit.test.lua

diff --git a/src/box/iproto.cc b/src/box/iproto.cc
index fe502b51b..585e8cc83 100644
--- a/src/box/iproto.cc
+++ b/src/box/iproto.cc
@@ -1084,10 +1084,11 @@ net_discard_input(struct cmsg *m)
 {
 	struct iproto_msg *msg = container_of(m, struct iproto_msg,
 					      discard_input);
+	struct iproto_connection *conn = msg->connection;
 	msg->p_ibuf->rpos += msg->len;
 	msg->len = 0;
-	msg->connection->long_poll_requests++;
-	iproto_resume();
+	conn->long_poll_requests++;
+	ev_feed_event(conn->loop, &conn->input, EV_READ);
 }
 
 static void
diff --git a/test/box/request_limit.result b/test/box/request_limit.result
new file mode 100644
index 000000000..464528b41
--- /dev/null
+++ b/test/box/request_limit.result
@@ -0,0 +1,114 @@
+test_run = require('test_run').new()
+---
+...
+fiber = require('fiber')
+---
+...
+net_box = require('net.box')
+---
+...
+box.schema.user.grant('guest', 'read,write,execute', 'universe')
+---
+...
+conn = net_box.connect(box.cfg.listen)
+---
+...
+conn2 = net_box.connect(box.cfg.listen)
+---
+...
+active = 0
+---
+...
+continue = false
+---
+...
+limit = 768
+---
+...
+run_max = (limit - 100) / 2
+---
+...
+old_readahead = box.cfg.readahead
+---
+...
+box.cfg{readahead = 9000}
+---
+...
+long_str = string.rep('a', 1000)
+---
+...
+test_run:cmd("setopt delimiter ';'")
+---
+- true
+...
+function do_long_f(...)
+	active = active + 1
+	while not continue do
+		fiber.sleep(0.1)
+	end
+	active = active - 1
+end;
+---
+...
+function do_long(c)
+	c:call('do_long_f', {long_str})
+end;
+---
+...
+function run_workers(c)
+	continue = false
+	for i = 1, run_max do
+		fiber.create(do_long, c)
+	end
+end;
+---
+...
+-- Wait until 'active' stops growing - it means, that the input
+-- is blocked.
+function wait_block()
+	local old_val = -1
+	while old_val ~= active do
+		old_val = active
+		fiber.sleep(0.1)
+	end
+end;
+---
+...
+test_run:cmd("setopt delimiter ''");
+---
+- true
+...
+--
+-- Test that message count limit is reachable.
+--
+run_workers(conn)
+---
+...
+run_workers(conn2)
+---
+...
+wait_block()
+---
+...
+active == run_max * 2 or active
+---
+- true
+...
+continue = true
+---
+...
+while active ~= 0 do fiber.sleep(0.01) end
+---
+...
+conn2:close()
+---
+...
+conn:close()
+---
+...
+box.schema.user.revoke('guest', 'read,write,execute', 'universe')
+---
+...
+box.cfg{readahead = old_readahead}
+---
+...
diff --git a/test/box/request_limit.test.lua b/test/box/request_limit.test.lua
new file mode 100644
index 000000000..81298d91d
--- /dev/null
+++ b/test/box/request_limit.test.lua
@@ -0,0 +1,63 @@
+test_run = require('test_run').new()
+
+fiber = require('fiber')
+net_box = require('net.box')
+
+box.schema.user.grant('guest', 'read,write,execute', 'universe')
+conn = net_box.connect(box.cfg.listen)
+conn2 = net_box.connect(box.cfg.listen)
+active = 0
+continue = false
+limit = 768
+run_max = (limit - 100) / 2
+
+old_readahead = box.cfg.readahead
+box.cfg{readahead = 9000}
+long_str = string.rep('a', 1000)
+
+test_run:cmd("setopt delimiter ';'")
+function do_long_f(...)
+	active = active + 1
+	while not continue do
+		fiber.sleep(0.1)
+	end
+	active = active - 1
+end;
+
+function do_long(c)
+	c:call('do_long_f', {long_str})
+end;
+
+function run_workers(c)
+	continue = false
+	for i = 1, run_max do
+		fiber.create(do_long, c)
+	end
+end;
+
+-- Wait until 'active' stops growing - it means, that the input
+-- is blocked.
+function wait_block()
+	local old_val = -1
+	while old_val ~= active do
+		old_val = active
+		fiber.sleep(0.1)
+	end
+end;
+test_run:cmd("setopt delimiter ''");
+
+--
+-- Test that message count limit is reachable.
+--
+run_workers(conn)
+run_workers(conn2)
+wait_block()
+active == run_max * 2 or active
+continue = true
+while active ~= 0 do fiber.sleep(0.01) end
+
+conn2:close()
+conn:close()
+
+box.schema.user.revoke('guest', 'read,write,execute', 'universe')
+box.cfg{readahead = old_readahead}
-- 
2.15.1 (Apple Git-101)

Re: [PATCH 2/3] iproto: fix error with input discarding

[Vladimir Davydov]

On Sat, Apr 21, 2018 at 01:52:10AM +0300, Vladislav Shpilevoy wrote:
> Long-polling request has a feature allowing to discard an input
> buffer in a connection before the main request is finished.
> 
> Before the patch discard just calls iproto_resume() trying to
> notify libev, that is can get new data. But is makes no sense,
> because iproto_resume() continues only connections stopped due
> to reached limit of maximal requests in fly, but not connections
> whose buffer is overflowed. Such stopped connections can be
> continued only after a request is complete.
> 
> To continue read from the connection whose buffer was freed by
> discarding long-poll it is necessary to explicitly feed to it
> EV_READ event. On this event iproto_connection_on_input will read
> a blocked data if it exists.
> ---
>  src/box/iproto.cc               |   5 +-
>  test/box/request_limit.result   | 114 ++++++++++++++++++++++++++++++++++++++++
>  test/box/request_limit.test.lua |  63 ++++++++++++++++++++++
>  3 files changed, 180 insertions(+), 2 deletions(-)
>  create mode 100644 test/box/request_limit.result
>  create mode 100644 test/box/request_limit.test.lua

Ack

[PATCH 3/3] iproto: allow to configure IPROTO_MSG_MAX

[Vladislav Shpilevoy]

IPROTO_MSG_MAX is a constant that restricts count of requests in
fly. It allows to do not produce too many fibers in TX thread,
that would lead to too big overhead on fibers switching, their
stack storing.

But some users have powerful metal on which Tarantool
IPROTO_MSG_MAX constant is not serious. The patch exposes it as
a configuration runtime parameter.

'iproto_msg_max' is its name. If a user sees that IProto thread
is stuck due to too many requests, it can change iproto_msg_max
in runtime, and IProto thread immediately starts processing
pending requests.

'iproto_msg_max' can be decreased, but obviously it can not stop
already runned requests, so if now in IProto thread request count
is > new 'iproto_msg_max' value, then it takes some time until
some requests will be finished.

Closes #3320
---
 src/box/box.cc                  |   7 +++
 src/box/box.h                   |   1 +
 src/box/iproto.cc               |  70 +++++++++++++++++------
 src/box/iproto.h                |   3 +
 src/box/lua/cfg.cc              |  12 ++++
 src/box/lua/load_cfg.lua        |   3 +
 test/app-tap/init_script.result |  73 ++++++++++++------------
 test/box/admin.result           |   2 +
 test/box/cfg.result             |  24 ++++++++
 test/box/cfg.test.lua           |   9 +++
 test/box/request_limit.result   | 119 +++++++++++++++++++++++++++++++++++++++-
 test/box/request_limit.test.lua |  55 ++++++++++++++++++-
 12 files changed, 322 insertions(+), 56 deletions(-)

diff --git a/src/box/box.cc b/src/box/box.cc
index d2dfc5b5f..80684ad48 100644
--- a/src/box/box.cc
+++ b/src/box/box.cc
@@ -759,6 +759,12 @@ box_set_vinyl_timeout(void)
 	vinyl_engine_set_timeout(vinyl,	cfg_getd("vinyl_timeout"));
 }
 
+void
+box_set_iproto_msg_max(void)
+{
+	iproto_set_msg_max(cfg_geti("iproto_msg_max"));
+}
+
 /* }}} configuration bindings */
 
 /**
@@ -1735,6 +1741,7 @@ box_cfg_xc(void)
 	box_check_instance_uuid(&instance_uuid);
 	box_check_replicaset_uuid(&replicaset_uuid);
 
+	box_set_iproto_msg_max();
 	box_set_checkpoint_count();
 	box_set_too_long_threshold();
 	box_set_replication_timeout();
diff --git a/src/box/box.h b/src/box/box.h
index c9b5aad01..712e21191 100644
--- a/src/box/box.h
+++ b/src/box/box.h
@@ -181,6 +181,7 @@ void box_set_vinyl_cache(void);
 void box_set_vinyl_timeout(void);
 void box_set_replication_timeout(void);
 void box_set_replication_connect_quorum(void);
+void box_set_iproto_msg_max(void);
 
 extern "C" {
 #endif /* defined(__cplusplus) */
diff --git a/src/box/iproto.cc b/src/box/iproto.cc
index 585e8cc83..1266eb255 100644
--- a/src/box/iproto.cc
+++ b/src/box/iproto.cc
@@ -63,8 +63,7 @@
 #include "applier.h"
 #include "cfg.h"
 
-/* The number of iproto messages in flight */
-enum { IPROTO_MSG_MAX = 768 };
+enum { IPROTO_MSG_MAX_MIN = 768 };
 
 /**
  * Network readahead. A signed integer to avoid
@@ -83,6 +82,9 @@ enum { IPROTO_MSG_MAX = 768 };
  */
 unsigned iproto_readahead = 16320;
 
+/* The maximal number of iproto messages in flight. */
+static int iproto_msg_max = IPROTO_MSG_MAX_MIN;
+
 /**
  * How big is a buffer which needs to be shrunk before
  * it is put back into buffer cache.
@@ -381,7 +383,7 @@ iproto_must_stop_input()
 {
 	size_t connection_count = mempool_count(&iproto_connection_pool);
 	size_t request_count = mempool_count(&iproto_msg_pool);
-	return request_count > connection_count + IPROTO_MSG_MAX;
+	return request_count > connection_count + iproto_msg_max;
 }
 
 /**
@@ -1623,7 +1625,7 @@ net_cord_f(va_list /* ap */)
 	cbus_endpoint_create(&endpoint, "net", fiber_schedule_cb, fiber());
 	/* Create a pipe to "tx" thread. */
 	cpipe_create(&tx_pipe, "tx");
-	cpipe_set_max_input(&tx_pipe, IPROTO_MSG_MAX/2);
+	cpipe_set_max_input(&tx_pipe, iproto_msg_max / 2);
 	/* Process incomming messages. */
 	cbus_loop(&endpoint);
 
@@ -1651,29 +1653,47 @@ iproto_init()
 
 	/* Create a pipe to "net" thread. */
 	cpipe_create(&net_pipe, "net");
-	cpipe_set_max_input(&net_pipe, IPROTO_MSG_MAX/2);
+	cpipe_set_max_input(&net_pipe, iproto_msg_max / 2);
 }
 
 /**
  * Since there is no way to "synchronously" change the
- * state of the io thread, to change the listen port
- * we need to bounce a couple of messages to and
- * from this thread.
+ * state of the io thread, to change the listen port or max
+ * message count in fly it is needed to bounce a couple of
+ * messages to and from this thread.
  */
 struct iproto_cfg_msg: public cbus_call_msg
 {
+	/** New URI to bind to. */
 	const char *uri;
+	bool need_update_uri;
+
+	/** New IProto max message count in fly. */
+	int iproto_msg_max;
+	bool need_update_msg_max;
 };
 
+static struct iproto_cfg_msg cfg_msg;
+
 static int
 iproto_do_cfg(struct cbus_call_msg *m)
 {
-	const char *uri  = ((struct iproto_cfg_msg *) m)->uri;
+	assert(m == &cfg_msg);
 	try {
-		if (evio_service_is_active(&binary))
-			evio_service_stop(&binary);
-		if (uri != NULL)
-			evio_service_bind(&binary, uri);
+		if (cfg_msg.need_update_uri) {
+			if (evio_service_is_active(&binary))
+				evio_service_stop(&binary);
+			if (cfg_msg.uri != NULL)
+				evio_service_bind(&binary, cfg_msg.uri);
+		}
+		if (cfg_msg.need_update_msg_max) {
+			cpipe_set_max_input(&tx_pipe,
+					    cfg_msg.iproto_msg_max / 2);
+			int old = iproto_msg_max;
+			iproto_msg_max = cfg_msg.iproto_msg_max;
+			if (old < iproto_msg_max)
+				iproto_resume();
+		}
 	} catch (Exception *e) {
 		return -1;
 	}
@@ -1696,9 +1716,10 @@ iproto_do_listen(struct cbus_call_msg *m)
 void
 iproto_bind(const char *uri)
 {
-	static struct iproto_cfg_msg m;
-	m.uri = uri;
-	if (cbus_call(&net_pipe, &tx_pipe, &m, iproto_do_cfg,
+	memset(&cfg_msg, 0, sizeof(cfg_msg));
+	cfg_msg.need_update_uri = true;
+	cfg_msg.uri = uri;
+	if (cbus_call(&net_pipe, &tx_pipe, &cfg_msg, iproto_do_cfg,
 		      NULL, TIMEOUT_INFINITY))
 		diag_raise();
 }
@@ -1724,3 +1745,20 @@ iproto_reset_stat(void)
 {
 	rmean_cleanup(rmean_net);
 }
+
+void
+iproto_set_msg_max(int new_iproto_msg_max)
+{
+	if (new_iproto_msg_max < IPROTO_MSG_MAX_MIN) {
+		tnt_raise(ClientError, ER_CFG, "iproto_msg_max",
+			  tt_sprintf("minimal value is %d",
+				     IPROTO_MSG_MAX_MIN));
+	}
+	memset(&cfg_msg, 0, sizeof(cfg_msg));
+	cfg_msg.need_update_msg_max = true;
+	cfg_msg.iproto_msg_max = new_iproto_msg_max;
+	if (cbus_call(&net_pipe, &tx_pipe, &cfg_msg, iproto_do_cfg,
+		      NULL, TIMEOUT_INFINITY))
+		diag_raise();
+	cpipe_set_max_input(&net_pipe, new_iproto_msg_max / 2);
+}
diff --git a/src/box/iproto.h b/src/box/iproto.h
index 0268000da..a1dddc405 100644
--- a/src/box/iproto.h
+++ b/src/box/iproto.h
@@ -63,6 +63,9 @@ iproto_bind(const char *uri);
 void
 iproto_listen();
 
+void
+iproto_set_msg_max(int iproto_msg_max);
+
 #endif /* defined(__cplusplus) */
 
 #endif
diff --git a/src/box/lua/cfg.cc b/src/box/lua/cfg.cc
index 5e88ca348..1fd953011 100644
--- a/src/box/lua/cfg.cc
+++ b/src/box/lua/cfg.cc
@@ -220,6 +220,17 @@ lbox_cfg_set_vinyl_timeout(struct lua_State *L)
 	return 0;
 }
 
+static int
+lbox_cfg_set_iproto_msg_max(struct lua_State *L)
+{
+	try {
+		box_set_iproto_msg_max();
+	} catch (Exception *) {
+		luaT_error(L);
+	}
+	return 0;
+}
+
 static int
 lbox_cfg_set_worker_pool_threads(struct lua_State *L)
 {
@@ -275,6 +286,7 @@ box_lua_cfg_init(struct lua_State *L)
 		{"cfg_set_replication_timeout", lbox_cfg_set_replication_timeout},
 		{"cfg_set_replication_connect_quorum",
 			lbox_cfg_set_replication_connect_quorum},
+		{"cfg_set_iproto_msg_max", lbox_cfg_set_iproto_msg_max},
 		{NULL, NULL}
 	};
 
diff --git a/src/box/lua/load_cfg.lua b/src/box/lua/load_cfg.lua
index 3a5a6d46a..6ed30e016 100644
--- a/src/box/lua/load_cfg.lua
+++ b/src/box/lua/load_cfg.lua
@@ -63,6 +63,7 @@ local default_cfg = {
     feedback_enabled      = true,
     feedback_host         = "https://feedback.tarantool.io",
     feedback_interval     = 3600,
+    iproto_msg_max        = 768,
 }
 
 -- types of available options
@@ -123,6 +124,7 @@ local template_cfg = {
     feedback_enabled      = 'boolean',
     feedback_host         = 'string',
     feedback_interval     = 'number',
+    iproto_msg_max        = 'number',
 }
 
 local function normalize_uri(port)
@@ -195,6 +197,7 @@ local dynamic_cfg = {
     replication_timeout     = private.cfg_set_replication_timeout,
     replication_connect_quorum = private.cfg_set_replication_connect_quorum,
     replication_skip_conflict = function() end,
+    iproto_msg_max          = private.cfg_set_iproto_msg_max,
 }
 
 local dynamic_cfg_skip_at_load = {
diff --git a/test/app-tap/init_script.result b/test/app-tap/init_script.result
index 5625f1466..741f764af 100644
--- a/test/app-tap/init_script.result
+++ b/test/app-tap/init_script.result
@@ -12,42 +12,43 @@ box.cfg
 7	feedback_interval:3600
 8	force_recovery:false
 9	hot_standby:false
-10	listen:port
-11	log:tarantool.log
-12	log_format:plain
-13	log_level:5
-14	log_nonblock:true
-15	memtx_dir:.
-16	memtx_max_tuple_size:1048576
-17	memtx_memory:107374182
-18	memtx_min_tuple_size:16
-19	pid_file:box.pid
-20	read_only:false
-21	readahead:16320
-22	replication_connect_timeout:4
-23	replication_skip_conflict:false
-24	replication_sync_lag:10
-25	replication_timeout:1
-26	rows_per_wal:500000
-27	slab_alloc_factor:1.05
-28	too_long_threshold:0.5
-29	vinyl_bloom_fpr:0.05
-30	vinyl_cache:134217728
-31	vinyl_dir:.
-32	vinyl_max_tuple_size:1048576
-33	vinyl_memory:134217728
-34	vinyl_page_size:8192
-35	vinyl_range_size:1073741824
-36	vinyl_read_threads:1
-37	vinyl_run_count_per_level:2
-38	vinyl_run_size_ratio:3.5
-39	vinyl_timeout:60
-40	vinyl_write_threads:2
-41	wal_dir:.
-42	wal_dir_rescan_delay:2
-43	wal_max_size:268435456
-44	wal_mode:write
-45	worker_pool_threads:4
+10	iproto_msg_max:768
+11	listen:port
+12	log:tarantool.log
+13	log_format:plain
+14	log_level:5
+15	log_nonblock:true
+16	memtx_dir:.
+17	memtx_max_tuple_size:1048576
+18	memtx_memory:107374182
+19	memtx_min_tuple_size:16
+20	pid_file:box.pid
+21	read_only:false
+22	readahead:16320
+23	replication_connect_timeout:4
+24	replication_skip_conflict:false
+25	replication_sync_lag:10
+26	replication_timeout:1
+27	rows_per_wal:500000
+28	slab_alloc_factor:1.05
+29	too_long_threshold:0.5
+30	vinyl_bloom_fpr:0.05
+31	vinyl_cache:134217728
+32	vinyl_dir:.
+33	vinyl_max_tuple_size:1048576
+34	vinyl_memory:134217728
+35	vinyl_page_size:8192
+36	vinyl_range_size:1073741824
+37	vinyl_read_threads:1
+38	vinyl_run_count_per_level:2
+39	vinyl_run_size_ratio:3.5
+40	vinyl_timeout:60
+41	vinyl_write_threads:2
+42	wal_dir:.
+43	wal_dir_rescan_delay:2
+44	wal_max_size:268435456
+45	wal_mode:write
+46	worker_pool_threads:4
 --
 -- Test insert from detached fiber
 --
diff --git a/test/box/admin.result b/test/box/admin.result
index 2168c3adb..7a1432a76 100644
--- a/test/box/admin.result
+++ b/test/box/admin.result
@@ -36,6 +36,8 @@ cfg_filter(box.cfg)
     - false
   - - hot_standby
     - false
+  - - iproto_msg_max
+    - 768
   - - listen
     - <hidden>
   - - log
diff --git a/test/box/cfg.result b/test/box/cfg.result
index 28449d9cc..af3de4537 100644
--- a/test/box/cfg.result
+++ b/test/box/cfg.result
@@ -32,6 +32,8 @@ cfg_filter(box.cfg)
     - false
   - - hot_standby
     - false
+  - - iproto_msg_max
+    - 768
   - - listen
     - <hidden>
   - - log
@@ -129,6 +131,8 @@ cfg_filter(box.cfg)
     - false
   - - hot_standby
     - false
+  - - iproto_msg_max
+    - 768
   - - listen
     - <hidden>
   - - log
@@ -411,6 +415,26 @@ test_run:cmd("cleanup server cfg_tester")
 ---
 - true
 ...
+--
+-- gh-3320: box.cfg{iproto_msg_max}.
+--
+box.cfg{iproto_msg_max = 'invalid'}
+---
+- error: 'Incorrect value for option ''iproto_msg_max'': should be of type number'
+...
+box.cfg{iproto_msg_max = 10}
+---
+- error: 'Incorrect value for option ''iproto_msg_max'': minimal value is 768'
+...
+old = box.cfg.iproto_msg_max
+---
+...
+box.cfg{iproto_msg_max = old + 1000}
+---
+...
+box.cfg{iproto_msg_max = old}
+---
+...
 test_run:cmd("clear filter")
 ---
 - true
diff --git a/test/box/cfg.test.lua b/test/box/cfg.test.lua
index a73ae395b..c2ac91c74 100644
--- a/test/box/cfg.test.lua
+++ b/test/box/cfg.test.lua
@@ -81,4 +81,13 @@ test_run:cmd("switch default")
 test_run:cmd("stop server cfg_tester")
 test_run:cmd("cleanup server cfg_tester")
 
+--
+-- gh-3320: box.cfg{iproto_msg_max}.
+--
+box.cfg{iproto_msg_max = 'invalid'}
+box.cfg{iproto_msg_max = 10}
+old = box.cfg.iproto_msg_max
+box.cfg{iproto_msg_max = old + 1000}
+box.cfg{iproto_msg_max = old}
+
 test_run:cmd("clear filter")
diff --git a/test/box/request_limit.result b/test/box/request_limit.result
index 464528b41..acdac2493 100644
--- a/test/box/request_limit.result
+++ b/test/box/request_limit.result
@@ -22,7 +22,7 @@ active = 0
 continue = false
 ---
 ...
-limit = 768
+limit = box.cfg.iproto_msg_max
 ---
 ...
 run_max = (limit - 100) / 2
@@ -100,6 +100,121 @@ continue = true
 while active ~= 0 do fiber.sleep(0.01) end
 ---
 ...
+--
+-- gh-3320: allow to change maximal count of messages.
+--
+--
+-- Increate maximal message count when nothing is blocked.
+--
+box.cfg{iproto_msg_max = limit * 2}
+---
+...
+run_max = limit * 2 - 100
+---
+...
+run_workers(conn)
+---
+...
+wait_block()
+---
+...
+active == run_max
+---
+- true
+...
+-- Max can be decreased back even if now the limit is violated.
+-- But a new input is blocked in such a case.
+box.cfg{iproto_msg_max = limit}
+---
+...
+old_active = active
+---
+...
+for i = 1, 300 do fiber.create(do_long, conn) end
+---
+...
+-- Afer time active cout is not changed - the input is blocked.
+wait_block()
+---
+...
+active == old_active
+---
+- true
+...
+continue = true
+---
+...
+while active ~= 0 do fiber.sleep(0.01) end
+---
+...
+--
+-- Check that changing iproto_msg_max can resume stopped
+-- connections.
+--
+run_max = limit / 2 + 100
+---
+...
+run_workers(conn)
+---
+...
+run_workers(conn2)
+---
+...
+wait_block()
+---
+...
+active >= limit
+---
+- true
+...
+active < run_max * 2
+---
+- true
+...
+box.cfg{iproto_msg_max = limit * 2}
+---
+...
+wait_block()
+---
+...
+active == run_max * 2
+---
+- true
+...
+continue = true
+---
+...
+while active ~= 0 do fiber.sleep(0.01) end
+---
+...
+--
+-- Test TX fiber pool size limit.
+--
+run_max = 2500
+---
+...
+box.cfg{iproto_msg_max = 5000}
+---
+...
+run_workers(conn)
+---
+...
+run_workers(conn2)
+---
+...
+wait_block()
+---
+...
+active
+---
+- 4096
+...
+continue = true
+---
+...
+while active ~= 0 do fiber.sleep(0.01) end
+---
+...
 conn2:close()
 ---
 ...
@@ -109,6 +224,6 @@ conn:close()
 box.schema.user.revoke('guest', 'read,write,execute', 'universe')
 ---
 ...
-box.cfg{readahead = old_readahead}
+box.cfg{readahead = old_readahead, iproto_msg_max = limit}
 ---
 ...
diff --git a/test/box/request_limit.test.lua b/test/box/request_limit.test.lua
index 81298d91d..f002cea04 100644
--- a/test/box/request_limit.test.lua
+++ b/test/box/request_limit.test.lua
@@ -8,7 +8,7 @@ conn = net_box.connect(box.cfg.listen)
 conn2 = net_box.connect(box.cfg.listen)
 active = 0
 continue = false
-limit = 768
+limit = box.cfg.iproto_msg_max
 run_max = (limit - 100) / 2
 
 old_readahead = box.cfg.readahead
@@ -56,8 +56,59 @@ active == run_max * 2 or active
 continue = true
 while active ~= 0 do fiber.sleep(0.01) end
 
+--
+-- gh-3320: allow to change maximal count of messages.
+--
+
+--
+-- Increate maximal message count when nothing is blocked.
+--
+box.cfg{iproto_msg_max = limit * 2}
+run_max = limit * 2 - 100
+run_workers(conn)
+wait_block()
+active == run_max
+-- Max can be decreased back even if now the limit is violated.
+-- But a new input is blocked in such a case.
+box.cfg{iproto_msg_max = limit}
+old_active = active
+for i = 1, 300 do fiber.create(do_long, conn) end
+-- Afer time active cout is not changed - the input is blocked.
+wait_block()
+active == old_active
+continue = true
+while active ~= 0 do fiber.sleep(0.01) end
+
+--
+-- Check that changing iproto_msg_max can resume stopped
+-- connections.
+--
+run_max = limit / 2 + 100
+run_workers(conn)
+run_workers(conn2)
+wait_block()
+active >= limit
+active < run_max * 2
+box.cfg{iproto_msg_max = limit * 2}
+wait_block()
+active == run_max * 2
+continue = true
+while active ~= 0 do fiber.sleep(0.01) end
+
+--
+-- Test TX fiber pool size limit.
+--
+run_max = 2500
+box.cfg{iproto_msg_max = 5000}
+run_workers(conn)
+run_workers(conn2)
+wait_block()
+active
+continue = true
+while active ~= 0 do fiber.sleep(0.01) end
+
 conn2:close()
 conn:close()
 
 box.schema.user.revoke('guest', 'read,write,execute', 'universe')
-box.cfg{readahead = old_readahead}
+box.cfg{readahead = old_readahead, iproto_msg_max = limit}
-- 
2.15.1 (Apple Git-101)

Re: [PATCH 3/3] iproto: allow to configure IPROTO_MSG_MAX

[Vladimir Davydov]

On Sat, Apr 21, 2018 at 01:52:11AM +0300, Vladislav Shpilevoy wrote:
> IPROTO_MSG_MAX is a constant that restricts count of requests in
> fly. It allows to do not produce too many fibers in TX thread,
> that would lead to too big overhead on fibers switching, their
> stack storing.
> 
> But some users have powerful metal on which Tarantool
> IPROTO_MSG_MAX constant is not serious. The patch exposes it as
> a configuration runtime parameter.
> 
> 'iproto_msg_max' is its name. If a user sees that IProto thread
> is stuck due to too many requests, it can change iproto_msg_max
> in runtime, and IProto thread immediately starts processing
> pending requests.
> 
> 'iproto_msg_max' can be decreased, but obviously it can not stop
> already runned requests, so if now in IProto thread request count
> is > new 'iproto_msg_max' value, then it takes some time until
> some requests will be finished.
> 
> Closes #3320
> ---
>  src/box/box.cc                  |   7 +++
>  src/box/box.h                   |   1 +
>  src/box/iproto.cc               |  70 +++++++++++++++++------
>  src/box/iproto.h                |   3 +
>  src/box/lua/cfg.cc              |  12 ++++
>  src/box/lua/load_cfg.lua        |   3 +
>  test/app-tap/init_script.result |  73 ++++++++++++------------
>  test/box/admin.result           |   2 +
>  test/box/cfg.result             |  24 ++++++++
>  test/box/cfg.test.lua           |   9 +++
>  test/box/request_limit.result   | 119 +++++++++++++++++++++++++++++++++++++++-
>  test/box/request_limit.test.lua |  55 ++++++++++++++++++-
>  12 files changed, 322 insertions(+), 56 deletions(-)
> 
> diff --git a/src/box/box.cc b/src/box/box.cc
> index d2dfc5b5f..80684ad48 100644
> --- a/src/box/box.cc
> +++ b/src/box/box.cc
> @@ -759,6 +759,12 @@ box_set_vinyl_timeout(void)
>  	vinyl_engine_set_timeout(vinyl,	cfg_getd("vinyl_timeout"));
>  }
>  
> +void
> +box_set_iproto_msg_max(void)
> +{
> +	iproto_set_msg_max(cfg_geti("iproto_msg_max"));
> +}
> +
>  /* }}} configuration bindings */
>  
>  /**
> @@ -1735,6 +1741,7 @@ box_cfg_xc(void)
>  	box_check_instance_uuid(&instance_uuid);
>  	box_check_replicaset_uuid(&replicaset_uuid);
>  
> +	box_set_iproto_msg_max();
>  	box_set_checkpoint_count();
>  	box_set_too_long_threshold();
>  	box_set_replication_timeout();
> diff --git a/src/box/box.h b/src/box/box.h
> index c9b5aad01..712e21191 100644
> --- a/src/box/box.h
> +++ b/src/box/box.h
> @@ -181,6 +181,7 @@ void box_set_vinyl_cache(void);
>  void box_set_vinyl_timeout(void);
>  void box_set_replication_timeout(void);
>  void box_set_replication_connect_quorum(void);
> +void box_set_iproto_msg_max(void);
>  
>  extern "C" {
>  #endif /* defined(__cplusplus) */
> diff --git a/src/box/iproto.cc b/src/box/iproto.cc
> index 585e8cc83..1266eb255 100644
> --- a/src/box/iproto.cc
> +++ b/src/box/iproto.cc
> @@ -63,8 +63,7 @@
>  #include "applier.h"
>  #include "cfg.h"
>  
> -/* The number of iproto messages in flight */
> -enum { IPROTO_MSG_MAX = 768 };
> +enum { IPROTO_MSG_MAX_MIN = 768 };

Why do you forbid to set iproto_msg_max to 1 for instance? Why do we
have to allow at least 768 messages in flight? If there's no specific
reason, I'd prefer to remove this artificial lower bound.

>  
>  /**
>   * Network readahead. A signed integer to avoid
> @@ -83,6 +82,9 @@ enum { IPROTO_MSG_MAX = 768 };
>   */
>  unsigned iproto_readahead = 16320;
>  
> +/* The maximal number of iproto messages in flight. */
> +static int iproto_msg_max = IPROTO_MSG_MAX_MIN;
> +
>  /**
>   * How big is a buffer which needs to be shrunk before
>   * it is put back into buffer cache.
> @@ -381,7 +383,7 @@ iproto_must_stop_input()
>  {
>  	size_t connection_count = mempool_count(&iproto_connection_pool);
>  	size_t request_count = mempool_count(&iproto_msg_pool);
> -	return request_count > connection_count + IPROTO_MSG_MAX;
> +	return request_count > connection_count + iproto_msg_max;
>  }
>  
>  /**
> @@ -1623,7 +1625,7 @@ net_cord_f(va_list /* ap */)
>  	cbus_endpoint_create(&endpoint, "net", fiber_schedule_cb, fiber());
>  	/* Create a pipe to "tx" thread. */
>  	cpipe_create(&tx_pipe, "tx");
> -	cpipe_set_max_input(&tx_pipe, IPROTO_MSG_MAX/2);
> +	cpipe_set_max_input(&tx_pipe, iproto_msg_max / 2);
>  	/* Process incomming messages. */
>  	cbus_loop(&endpoint);
>  
> @@ -1651,29 +1653,47 @@ iproto_init()
>  
>  	/* Create a pipe to "net" thread. */
>  	cpipe_create(&net_pipe, "net");
> -	cpipe_set_max_input(&net_pipe, IPROTO_MSG_MAX/2);
> +	cpipe_set_max_input(&net_pipe, iproto_msg_max / 2);
>  }
>  
>  /**
>   * Since there is no way to "synchronously" change the
> - * state of the io thread, to change the listen port
> - * we need to bounce a couple of messages to and
> - * from this thread.
> + * state of the io thread, to change the listen port or max
> + * message count in fly it is needed to bounce a couple of
> + * messages to and from this thread.
>   */
>  struct iproto_cfg_msg: public cbus_call_msg
>  {
> +	/** New URI to bind to. */
>  	const char *uri;
> +	bool need_update_uri;
> +
> +	/** New IProto max message count in fly. */
> +	int iproto_msg_max;
> +	bool need_update_msg_max;
>  };
>  
> +static struct iproto_cfg_msg cfg_msg;
> +
>  static int
>  iproto_do_cfg(struct cbus_call_msg *m)
>  {
> -	const char *uri  = ((struct iproto_cfg_msg *) m)->uri;
> +	assert(m == &cfg_msg);
>  	try {
> -		if (evio_service_is_active(&binary))
> -			evio_service_stop(&binary);
> -		if (uri != NULL)
> -			evio_service_bind(&binary, uri);
> +		if (cfg_msg.need_update_uri) {
> +			if (evio_service_is_active(&binary))
> +				evio_service_stop(&binary);
> +			if (cfg_msg.uri != NULL)
> +				evio_service_bind(&binary, cfg_msg.uri);
> +		}
> +		if (cfg_msg.need_update_msg_max) {
> +			cpipe_set_max_input(&tx_pipe,
> +					    cfg_msg.iproto_msg_max / 2);
> +			int old = iproto_msg_max;
> +			iproto_msg_max = cfg_msg.iproto_msg_max;
> +			if (old < iproto_msg_max)
> +				iproto_resume();
> +		}

This is a matter of personal taste, but I'd prefer to not introduce
these extra flags, i.e.

	if (cfg_msg.uri != NULL)
		/* set uri */

	if (cfg_msg.iproto_msg_max > 0)
		/* update iproto_msg max */

>  	} catch (Exception *e) {
>  		return -1;
>  	}
> @@ -1696,9 +1716,10 @@ iproto_do_listen(struct cbus_call_msg *m)
>  void
>  iproto_bind(const char *uri)
>  {
> -	static struct iproto_cfg_msg m;
> -	m.uri = uri;
> -	if (cbus_call(&net_pipe, &tx_pipe, &m, iproto_do_cfg,
> +	memset(&cfg_msg, 0, sizeof(cfg_msg));
> +	cfg_msg.need_update_uri = true;
> +	cfg_msg.uri = uri;
> +	if (cbus_call(&net_pipe, &tx_pipe, &cfg_msg, iproto_do_cfg,
>  		      NULL, TIMEOUT_INFINITY))
>  		diag_raise();
>  }
> @@ -1724,3 +1745,20 @@ iproto_reset_stat(void)
>  {
>  	rmean_cleanup(rmean_net);
>  }
> +
> +void
> +iproto_set_msg_max(int new_iproto_msg_max)
> +{
> +	if (new_iproto_msg_max < IPROTO_MSG_MAX_MIN) {
> +		tnt_raise(ClientError, ER_CFG, "iproto_msg_max",
> +			  tt_sprintf("minimal value is %d",
> +				     IPROTO_MSG_MAX_MIN));
> +	}
> +	memset(&cfg_msg, 0, sizeof(cfg_msg));
> +	cfg_msg.need_update_msg_max = true;
> +	cfg_msg.iproto_msg_max = new_iproto_msg_max;
> +	if (cbus_call(&net_pipe, &tx_pipe, &cfg_msg, iproto_do_cfg,
> +		      NULL, TIMEOUT_INFINITY))
> +		diag_raise();
> +	cpipe_set_max_input(&net_pipe, new_iproto_msg_max / 2);
> +}

AFAIR IPROTO_MSG_MAX is related to FIBER_POOL_SIZE so if we increase the
former, we should increase the latter as well, no?

> diff --git a/test/box/request_limit.test.lua b/test/box/request_limit.test.lua
> index 81298d91d..f002cea04 100644
> --- a/test/box/request_limit.test.lua
> +++ b/test/box/request_limit.test.lua
> @@ -8,7 +8,7 @@ conn = net_box.connect(box.cfg.listen)
>  conn2 = net_box.connect(box.cfg.listen)
>  active = 0
>  continue = false
> -limit = 768
> +limit = box.cfg.iproto_msg_max
>  run_max = (limit - 100) / 2
>  
>  old_readahead = box.cfg.readahead
> @@ -56,8 +56,59 @@ active == run_max * 2 or active
>  continue = true
>  while active ~= 0 do fiber.sleep(0.01) end
>  
> +--
> +-- gh-3320: allow to change maximal count of messages.
> +--
> +
> +--
> +-- Increate maximal message count when nothing is blocked.
> +--
> +box.cfg{iproto_msg_max = limit * 2}
> +run_max = limit * 2 - 100
> +run_workers(conn)
> +wait_block()
> +active == run_max
> +-- Max can be decreased back even if now the limit is violated.
> +-- But a new input is blocked in such a case.
> +box.cfg{iproto_msg_max = limit}
> +old_active = active
> +for i = 1, 300 do fiber.create(do_long, conn) end
> +-- Afer time active cout is not changed - the input is blocked.
> +wait_block()
> +active == old_active
> +continue = true
> +while active ~= 0 do fiber.sleep(0.01) end
> +
> +--
> +-- Check that changing iproto_msg_max can resume stopped
> +-- connections.
> +--
> +run_max = limit / 2 + 100
> +run_workers(conn)
> +run_workers(conn2)
> +wait_block()
> +active >= limit
> +active < run_max * 2
> +box.cfg{iproto_msg_max = limit * 2}
> +wait_block()
> +active == run_max * 2
> +continue = true
> +while active ~= 0 do fiber.sleep(0.01) end
> +
> +--
> +-- Test TX fiber pool size limit.
> +--
> +run_max = 2500
> +box.cfg{iproto_msg_max = 5000}
> +run_workers(conn)
> +run_workers(conn2)
> +wait_block()
> +active
> +continue = true
> +while active ~= 0 do fiber.sleep(0.01) end
> +
>  conn2:close()
>  conn:close()
>  
>  box.schema.user.revoke('guest', 'read,write,execute', 'universe')
> -box.cfg{readahead = old_readahead}
> +box.cfg{readahead = old_readahead, iproto_msg_max = limit}

If I run the test several times in a row, it fails. Please fix.

================================================================================
TEST                                            PARAMS          RESULT
---------------------------------------------------------------------------
box/request_limit.test.lua                                      [ pass ]
box/request_limit.test.lua                                      [ fail ]

Test failed! Result content mismatch:
--- box/request_limit.result    Mon Apr 23 14:19:48 2018
+++ box/request_limit.reject    Mon Apr 23 14:32:52 2018
@@ -179,7 +179,7 @@
 ...
 active == run_max * 2
 ---
-- true
+- false
 ...
 continue = true
 ---

Re: [tarantool-patches] Re: [PATCH 3/3] iproto: allow to configure IPROTO_MSG_MAX

[Vladislav Shpilevoy]

Hello. Thanks for review! See my comments below.

During fixing the patch I found and fixed a new problem in iproto,
that I pushed as a separate commit.

And now the patchset is grossly changed (1 commit is removed,
1 is added, 1 has big diff) so I will push a new one with v2.


On 23/04/2018 14:34, Vladimir Davydov wrote:
> On Sat, Apr 21, 2018 at 01:52:11AM +0300, Vladislav Shpilevoy wrote:
>> IPROTO_MSG_MAX is a constant that restricts count of requests in
>> fly. It allows to do not produce too many fibers in TX thread,
>> that would lead to too big overhead on fibers switching, their
>> stack storing.
>>
>> But some users have powerful metal on which Tarantool
>> IPROTO_MSG_MAX constant is not serious. The patch exposes it as
>> a configuration runtime parameter.
>>
>> 'iproto_msg_max' is its name. If a user sees that IProto thread
>> is stuck due to too many requests, it can change iproto_msg_max
>> in runtime, and IProto thread immediately starts processing
>> pending requests.
>>
>> 'iproto_msg_max' can be decreased, but obviously it can not stop
>> already runned requests, so if now in IProto thread request count
>> is > new 'iproto_msg_max' value, then it takes some time until
>> some requests will be finished.
>>
>> Closes #3320
>> ---
>>   src/box/box.cc                  |   7 +++
>>   src/box/box.h                   |   1 +
>>   src/box/iproto.cc               |  70 +++++++++++++++++------
>>   src/box/iproto.h                |   3 +
>>   src/box/lua/cfg.cc              |  12 ++++
>>   src/box/lua/load_cfg.lua        |   3 +
>>   test/app-tap/init_script.result |  73 ++++++++++++------------
>>   test/box/admin.result           |   2 +
>>   test/box/cfg.result             |  24 ++++++++
>>   test/box/cfg.test.lua           |   9 +++
>>   test/box/request_limit.result   | 119 +++++++++++++++++++++++++++++++++++++++-
>>   test/box/request_limit.test.lua |  55 ++++++++++++++++++-
>>   12 files changed, 322 insertions(+), 56 deletions(-)
>>
>> -/* The number of iproto messages in flight */
>> -enum { IPROTO_MSG_MAX = 768 };
>> +enum { IPROTO_MSG_MAX_MIN = 768 };
> 
> Why do you forbid to set iproto_msg_max to 1 for instance? Why do we
> have to allow at least 768 messages in flight? If there's no specific
> reason, I'd prefer to remove this artificial lower bound.

No concrete reason. Just wanted to protect a user from setting too small
limit. But ok, I fixed this on branch, and set a limit to 2 (it can not
be 1 - there must be availability to have 1 message in fly from iproto to
tx and back (see cpipe_set_max_input - it is msg_max / 2 for net_pipe and
tx_pipe).

>> +		if (cfg_msg.need_update_uri) {
>> +			if (evio_service_is_active(&binary))
>> +				evio_service_stop(&binary);
>> +			if (cfg_msg.uri != NULL)
>> +				evio_service_bind(&binary, cfg_msg.uri);
>> +		}
>> +		if (cfg_msg.need_update_msg_max) {
>> +			cpipe_set_max_input(&tx_pipe,
>> +					    cfg_msg.iproto_msg_max / 2);
>> +			int old = iproto_msg_max;
>> +			iproto_msg_max = cfg_msg.iproto_msg_max;
>> +			if (old < iproto_msg_max)
>> +				iproto_resume();
>> +		}
> 
> This is a matter of personal taste, but I'd prefer to not introduce
> these extra flags, i.e.

It is not possible for URI, because URI == NULL is possible update. So
for URI the flag is necessary. For msg_max I added this for unifying. If you
want, I can remove need_update_msg_max. Must I do it?

> 
> 	if (cfg_msg.uri != NULL)
> 		/* set uri */
> 
> 	if (cfg_msg.iproto_msg_max > 0)
> 		/* update iproto_msg max */
> 
>> +	cpipe_set_max_input(&net_pipe, new_iproto_msg_max / 2);
>> +}
> 
> AFAIR IPROTO_MSG_MAX is related to FIBER_POOL_SIZE so if we increase the
> former, we should increase the latter as well, no?

Yes, it is related. I made it configurable on the branch.

>>   box.schema.user.revoke('guest', 'read,write,execute', 'universe')
>> -box.cfg{readahead = old_readahead}
>> +box.cfg{readahead = old_readahead, iproto_msg_max = limit}
> 
> If I run the test several times in a row, it fails. Please fix.

Done.

Re: [tarantool-patches] Re: [PATCH 3/3] iproto: allow to configure IPROTO_MSG_MAX

[Vladimir Davydov]

On Mon, Apr 23, 2018 at 08:00:13PM +0300, Vladislav Shpilevoy wrote:
> > > +		if (cfg_msg.need_update_uri) {
> > > +			if (evio_service_is_active(&binary))
> > > +				evio_service_stop(&binary);
> > > +			if (cfg_msg.uri != NULL)
> > > +				evio_service_bind(&binary, cfg_msg.uri);
> > > +		}
> > > +		if (cfg_msg.need_update_msg_max) {
> > > +			cpipe_set_max_input(&tx_pipe,
> > > +					    cfg_msg.iproto_msg_max / 2);
> > > +			int old = iproto_msg_max;
> > > +			iproto_msg_max = cfg_msg.iproto_msg_max;
> > > +			if (old < iproto_msg_max)
> > > +				iproto_resume();
> > > +		}
> > 
> > This is a matter of personal taste, but I'd prefer to not introduce
> > these extra flags, i.e.
> 
> It is not possible for URI, because URI == NULL is possible update. So
> for URI the flag is necessary. For msg_max I added this for unifying. If you
> want, I can remove need_update_msg_max. Must I do it?

No need then. Leave it as is for consistency.