diff --git a/include/httpc_bench.hrl b/include/httpc_bench.hrl
index 7ce82a1..b8ebac7 100644
--- a/include/httpc_bench.hrl
+++ b/include/httpc_bench.hrl
@@ -5,5 +5,5 @@
 -define(PIPELINING, 1024).
 -define(PATH, <<"/">>).
 -define(PORT, 8080).
--define(TIMEOUT, 12000).
+-define(TIMEOUT, 300_000).
 -define(URL, <<"http://127.0.0.1:8080/">>).
diff --git a/rebar.config b/rebar.config
index 7fe1d07..3e12efb 100644
--- a/rebar.config
+++ b/rebar.config
@@ -7,7 +7,8 @@
     {git, "https://github.com/benoitc/hackney.git", {tag, "1.17.4"}}},
   % {ibrowse, ".*",
   %   {git, "https://github.com/cmullaparthi/ibrowse.git", {tag, "v4.4.0"}}},
-  {ehttpc, ".*", {git, "https://github.com/emqx/ehttpc", {tag, "0.1.11"}}},
+  % {ehttpc, ".*", {git, "https://github.com/emqx/ehttpc", {tag, "0.1.15"}}},
+  {ehttpc, ".*", {git, "https://github.com/emqx/ehttpc", {branch, "0404-refactor-collect-gen-calls-to-queue"}}},
   {timing, ".*",
     {git, "https://github.com/lpgauth/timing.git", {branch, "master"}}}
 ]}.
diff --git a/rebar.lock b/rebar.lock
deleted file mode 100644
index 2610f14..0000000
--- a/rebar.lock
+++ /dev/null
@@ -1,68 +0,0 @@
-{"1.1.0",
-[{<<"bear">>,
-  {git,"https://github.com/boundary/bear.git",
-       {ref,"119234548783af19b8ec75c879c5062676b92571"}},
-  1},
- {<<"buoy">>,
-  {git,"https://github.com/lpgauth/buoy.git",
-       {ref,"7c49e2d5ec6b35625004fb8842342ee28641e864"}},
-  0},
- {<<"certifi">>,{pkg,<<"certifi">>,<<"0.7.0">>},1},
- {<<"cowlib">>,{pkg,<<"cowlib">>,<<"1.0.0">>},1},
- {<<"dispcount">>,
-  {git,"https://github.com/ferd/dispcount.git",
-       {ref,"f466aecdb8ea2dda0996af08c3f2683dae612aed"}},
-  1},
- {<<"dlhttpc">>,
-  {git,"https://github.com/lpgauth/dlhttpc.git",
-       {ref,"ca9664358f3d7e63b58cda48545a57c44189a16b"}},
-  0},
- {<<"edown">>,
-  {git,"https://github.com/uwiger/edown.git",
-       {ref,"b7c8eb0ac1859f8fce11cbfe3526f5ec83194776"}},
-  2},
- {<<"fqc">>,
-  {git,"https://github.com/project-fifo/fqc.git",
-       {ref,"ad62f8121414ed026a6a9f564b1856191ab7d1fc"}},
-  2},
- {<<"gproc">>,{pkg,<<"gproc">>,<<"0.5.0">>},1},
- {<<"granderl">>,{pkg,<<"granderl">>,<<"0.1.5">>},2},
- {<<"hackney">>,
-  {git,"https://github.com/benoitc/hackney.git",
-       {ref,"b3814c981cb600211f0b1b0e133c4dbffc8299bc"}},
-  0},
- {<<"hdr_histogram">>,
-  {git,"https://github.com/HdrHistogram/hdr_histogram_erl.git",
-       {ref,"46a4f86f3a9b72181859c2a30c8039c5d486248b"}},
-  1},
- {<<"ibrowse">>,
-  {git,"https://github.com/cmullaparthi/ibrowse.git",
-       {ref,"7529807170cf3c8f6a8c5c95526e670420ff591b"}},
-  0},
- {<<"idna">>,{pkg,<<"idna">>,<<"1.2.0">>},1},
- {<<"katipo">>,
-  {git,"https://github.com/puzza007/katipo.git",
-       {ref,"40660e346d29fec133087ff64e87552b0de19da1"}},
-  0},
- {<<"metal">>,{pkg,<<"metal">>,<<"0.1.0">>},2},
- {<<"metrics">>,{pkg,<<"metrics">>,<<"1.1.0">>},1},
- {<<"mimerl">>,{pkg,<<"mimerl">>,<<"1.0.2">>},1},
- {<<"shackle">>,{pkg,<<"shackle">>,<<"0.5.0">>},1},
- {<<"ssl_verify_fun">>,{pkg,<<"ssl_verify_fun">>,<<"1.1.1">>},1},
- {<<"timing">>,
-  {git,"https://github.com/lpgauth/timing.git",
-       {ref,"8a3c0320692fe48a266b29854e4e27b99f6a7a95"}},
-  0}]}.
-[
-{pkg_hash,[
- {<<"certifi">>, <<"861A57F3808F7EB0C2D1802AFEAAE0FA5DE813B0DF0979153CBAFCD853ABABAF">>},
- {<<"cowlib">>, <<"397D890D669E56D486B0B5329973AD1A07012412BC110D34A737698DD6941741">>},
- {<<"gproc">>, <<"2DF2D886F8F8A7B81A4B04AA17972B5965BBC5BF0100EA6D8E8AC6A0E7389AFE">>},
- {<<"granderl">>, <<"F20077A68BD80B8D8783BD15A052813C6483771DEC1A5B837D307CBE92F14122">>},
- {<<"idna">>, <<"AC62EE99DA068F43C50DC69ACF700E03A62A348360126260E87F2B54ECED86B2">>},
- {<<"metal">>, <<"168E0AB553E3B8144547E353085CEDAA43C8769E0B7E43C0146C99C2C33507AC">>},
- {<<"metrics">>, <<"41450DFFBA18B1206BF44FA1AD4E29324D1E561617C2DAF4EF32E3CE50DF08F3">>},
- {<<"mimerl">>, <<"993F9B0E084083405ED8252B99460C4F0563E41729AB42D9074FD5E52439BE88">>},
- {<<"shackle">>, <<"1C90E21A8181D4750BDEBF203F6A7412659A4C04947591FBE71797B89BEC9600">>},
- {<<"ssl_verify_fun">>, <<"28A4D65B7F59893BC2C7DE786DEC1E1555BD742D336043FE644AE956C3497FBE">>}]}
-].
diff --git a/src/httpc_bench.erl b/src/httpc_bench.erl
index c67547b..819e530 100644
--- a/src/httpc_bench.erl
+++ b/src/httpc_bench.erl
@@ -5,33 +5,40 @@
     run/0
 ]).
 
--define(N, 2048000).
+-define(N, 10240).
 
 -define(CLIENTS, [
-    httpc_bench_buoy,
-    httpc_bench_ehttpc,
-    httpc_bench_hackney,
-    httpc_bench_httpc
+    % httpc_bench_buoy,
+    httpc_bench_ehttpc
+    % httpc_bench_hackney,
+    % httpc_bench_httpc
 ]).
 
-% -define(CONCURENCIES, [32, 64, 128, 512, 2048, 4096]).
-% -define(POOL_SIZES, [8, 16, 32, 64, 128, 256]).
-
 -define(CONCURENCIES, [10240]).
--define(POOL_SIZES, [1024]).
+-define(POOL_SIZES, [1]).
+
+% -define(CONCURENCIES, [20480]).
+% -define(POOL_SIZES, [16]).
+
+% -define(CONCURENCIES, [10240]).
+% -define(POOL_SIZES, [1024]).
 
 %% public
 run() ->
     error_logger:tty(false),
     io:format("Running benchmark...~n~n" ++
-        "Client  PoolSize  Concurency  Requests/s  Error %~n" ++
-        [$= || _ <- lists:seq(1, 49)] ++ "~n", []),
+        "Client  PoolSize  Concurency  Requests/s  Error % Success Totol Time(s)~n" ++
+        [$= || _ <- lists:seq(1, 71)] ++ "~n", []),
+    case lists:any(fun(C) -> ?N < C end, ?CONCURENCIES) of
+        true -> error(bad_iteration);
+        false -> ok
+    end,
     run_client(?CLIENTS, ?POOL_SIZES, ?CONCURENCIES, ?N).
 
 %% private
 lookup(Key, List) ->
     case lists:keyfind(Key, 1, List) of
-        false -> undefined;
+        false -> error({bad_lookup_key, Key});
         {_, Value} -> Value
     end.
 
@@ -66,7 +73,7 @@ run_concurency(Client, PoolSize, [Concurency | T], N) ->
     ]),
     Qps = lookup(success, Results) / (lookup(total_time, Results) / 1000000),
     Errors = lookup(errors, Results) / lookup(iterations, Results) * 100,
-    io:format("~-8s ~7B ~11B ~11B ~8.1f~n",
-        [Client2, PoolSize, Concurency, trunc(Qps), Errors]),
+    io:format("~-8s ~7B ~11B ~11B ~8.1f ~8B ~12.2f~n",
+        [Client2, PoolSize, Concurency, trunc(Qps), Errors, lookup(success, Results), (lookup(total_time, Results) / 1000000)]),
     Client:stop(),
     run_concurency(Client, PoolSize, T, N).
diff --git a/src/httpc_bench_ehttpc.erl b/src/httpc_bench_ehttpc.erl
index cd9b6b0..4a25b53 100644
--- a/src/httpc_bench_ehttpc.erl
+++ b/src/httpc_bench_ehttpc.erl
@@ -22,11 +22,11 @@ start(PoolSize) ->
     application:ensure_all_started(ehttpc),
     PoolOpts = [{host, "127.0.0.1"},
                 {port, 8080},
-                {enable_pipelining, true},
+                {enable_pipelining, false},
                 {pool_size, PoolSize},
                 {pool_type, random},
                 {connect_timeout, 5000},
-                {retry, 5},
+                {retry, 0},
                 {retry_timeout, 1000}
                 ],
     {ok, _} = ehttpc_sup:start_pool(httpc_bench, PoolOpts).
diff --git a/src/httpc_bench_server.erl b/src/httpc_bench_server.erl
index 8c79fdc..b13311c 100644
--- a/src/httpc_bench_server.erl
+++ b/src/httpc_bench_server.erl
@@ -13,10 +13,11 @@
 start() ->
     case get(?MODULE) of
         undefined ->
-            io:format("Server started...~n", []),
+            Sleep = sleep(),
+            io:format("HTTP Server started on port ~p, sleep=~p...~n", [?PORT, Sleep]),
             {ok, LSocket} = listen(),
             put(?MODULE, LSocket),
-            spawn(fun () -> accept(LSocket) end),
+            spawn(fun () -> accept(LSocket, Sleep) end),
             ok;
         _LSocket ->
             {error, already_started}
@@ -33,15 +34,26 @@ stop() ->
     end.
 
 %% private
-accept(LSocket) ->
+accept(LSocket, Sleep) ->
     case gen_tcp:accept(LSocket) of
         {ok, Socket} ->
-            spawn(fun() -> loop(Socket, <<>>) end),
-            accept(LSocket);
+            spawn_link(
+                fun() ->
+                    io:format(user, "started one server process ~p, sleep=~p\n", [Socket, Sleep]),
+                    loop(Socket, Sleep, <<>>)
+                end),
+            accept(LSocket, Sleep);
         {error, _Reason} ->
             ok
     end.
 
+sleep() ->
+   case os:getenv("SLEEP_PER_REQ") of
+       false -> 10;
+       "" -> 10;
+       N -> list_to_integer(N)
+   end.
+
 count_requests([<<>>], N) ->
     {N, <<>>};
 count_requests([Buffer], N) ->
@@ -61,10 +73,13 @@ listen() ->
     end),
     receive
         {ok, LSocket} ->
-            {ok, LSocket}
+            {ok, LSocket};
+        Other ->
+            io:format(user, "unexpected listen result: ~p\n", [Other]),
+            exit(kill)
     end.
 
-loop(Socket, Buffer) ->
+loop(Socket, Sleep, Buffer) ->
     case gen_tcp:recv(Socket, 0) of
         {ok, Data} ->
             Split = binary:split(<<Buffer/binary, Data/binary>>,
@@ -76,12 +91,16 @@ loop(Socket, Buffer) ->
                   "Date: Tue, 07 Mar 2017 01:10:09 GMT\r\n",
                   "Content-Length: 12\r\n\r\n",
                   "httpc_bench!">> || _ <- lists:seq(1, N)],
-            case gen_tcp:send(Socket, Responses) of
-                ok ->
-                    loop(Socket, Buffer2);
-                {error, _Reason} ->
-                    ok
-            end;
-        {error, _Reason} ->
-            ok
+            lists:foreach(
+                fun(R) ->
+                        case gen_tcp:send(Socket, R) of
+                            ok -> ok;
+                            {error, _} -> exit(normal)
+                        end,
+                        timer:sleep(Sleep)
+                end, Responses),
+            loop(Socket, Sleep, Buffer2);
+        {error, Reason} ->
+            io:format(user, "stopped one server process ~p: ~0p\n", [Socket, Reason]),
+            exit(normal)
     end.