2016年3月23日(水) 14:23 James Peach <jpeach@apache.org>:

> On Mar 21, 2016, at 6:57 PM, masaori@apache.org wrote:
>
> Repository: trafficserver
> Updated Branches:
>  refs/heads/master 1e9c9484c -> 0e6e5c151
>
>
> TS-4087: Reduce SETTINGS_MAX_CONCURRENT_STREAMS when too many streams
>
> Add below variables in records.config
> - proxy.config.http2.min_concurrent_streams_in
> - proxy.config.http2.max_active_streams_in
>
> When connection wide active stream are larger than proxy.config.http2.max_active_streams_in,
> SETTINGS_MAX_CONCURRENT_STREAMS is reduced to proxy.config.http2.min_concurrent_streams_in
> in new connections.
>
> If the value of proxy.config.http2.max_active_streams_in is 0, there is no limit.
>
> This closes #485
>
>
> Project: http://git-wip-us.apache.org/repos/asf/trafficserver/repo
> Commit: http://git-wip-us.apache.org/repos/asf/trafficserver/commit/0e6e5c15
> Tree: http://git-wip-us.apache.org/repos/asf/trafficserver/tree/0e6e5c15
> Diff: http://git-wip-us.apache.org/repos/asf/trafficserver/diff/0e6e5c15
>
> Branch: refs/heads/master
> Commit: 0e6e5c151cde5f06c15e295f663a98b2b7d37a6d
> Parents: 1e9c948
> Author: Masaori Koshiba <masaori@apache.org>
> Authored: Mon Feb 15 20:57:25 2016 +0900
> Committer: Masaori Koshiba <masaori@apache.org>
> Committed: Tue Mar 22 10:52:37 2016 +0900
>
> ----------------------------------------------------------------------
> mgmt/RecordsConfig.cc               |  4 ++++
> proxy/http2/HTTP2.cc                | 12 ++++++++---
> proxy/http2/HTTP2.h                 |  5 ++++-
> proxy/http2/Http2ConnectionState.cc | 35 ++++++++++++++++++++++++++++++++
> proxy/http2/Http2ConnectionState.h  |  4 +++-
> 5 files changed, 55 insertions(+), 5 deletions(-)
> ----------------------------------------------------------------------
>
>
> http://git-wip-us.apache.org/repos/asf/trafficserver/blob/0e6e5c15/mgmt/RecordsConfig.cc
> ----------------------------------------------------------------------
> diff --git a/mgmt/RecordsConfig.cc b/mgmt/RecordsConfig.cc
> index 0e963c9..b0e0e6a 100644
> --- a/mgmt/RecordsConfig.cc
> +++ b/mgmt/RecordsConfig.cc
> @@ -1977,6 +1977,10 @@ static const RecordElement RecordsConfig[] =
>   ,
>   {RECT_CONFIG, "proxy.config.http2.max_concurrent_streams_in", RECD_INT, "100", RECU_DYNAMIC, RR_NULL, RECC_STR, "^[0-9]+$", RECA_NULL}
>   ,
> +  {RECT_CONFIG, "proxy.config.http2.min_concurrent_streams_in", RECD_INT, "10", RECU_DYNAMIC, RR_NULL, RECC_STR, "^[0-9]+$", RECA_NULL}
> +  ,
> +  {RECT_CONFIG, "proxy.config.http2.max_active_streams_in", RECD_INT, "0", RECU_DYNAMIC, RR_NULL, RECC_STR, "^[0-9]+$", RECA_NULL}
> +  ,

Please document these new settings.
Sure.

>   {RECT_CONFIG, "proxy.config.http2.initial_window_size_in", RECD_INT, "1048576", RECU_DYNAMIC, RR_NULL, RECC_STR, "^[0-9]+$", RECA_NULL}
>   ,
>   {RECT_CONFIG, "proxy.config.http2.max_frame_size", RECD_INT, "16384", RECU_DYNAMIC, RR_NULL, RECC_STR, "^[0-9]+$", RECA_NULL}
>
> http://git-wip-us.apache.org/repos/asf/trafficserver/blob/0e6e5c15/proxy/http2/HTTP2.cc
> ----------------------------------------------------------------------
> diff --git a/proxy/http2/HTTP2.cc b/proxy/http2/HTTP2.cc
> index 5cb9d79..c9ea2bc 100644
> --- a/proxy/http2/HTTP2.cc
> +++ b/proxy/http2/HTTP2.cc
> @@ -727,7 +727,10 @@ http2_decode_header_blocks(HTTPHdr *hdr, const uint8_t *buf_start, const uint8_t
> }
>
> // Initialize this subsystem with librecords configs (for now)
> -uint32_t Http2::max_concurrent_streams = 100;
> +uint32_t Http2::max_concurrent_streams_in = 100;
> +uint32_t Http2::min_concurrent_streams_in = 10;
> +uint32_t Http2::max_active_streams_in = 0;
> +bool Http2::throttling = false;
> uint32_t Http2::initial_window_size = 1048576;
> uint32_t Http2::max_frame_size = 16384;
> uint32_t Http2::header_table_size = 4096;
> @@ -740,7 +743,9 @@ uint32_t Http2::active_timeout_in = 0;
> void
> Http2::init()
> {
> -  REC_EstablishStaticConfigInt32U(max_concurrent_streams, "proxy.config.http2.max_concurrent_streams_in");
> +  REC_EstablishStaticConfigInt32U(max_concurrent_streams_in, "proxy.config.http2.max_concurrent_streams_in");
> +  REC_EstablishStaticConfigInt32U(min_concurrent_streams_in, "proxy.config.http2.min_concurrent_streams_in");
> +  REC_EstablishStaticConfigInt32U(max_active_streams_in, "proxy.config.http2.max_active_streams_in");
>   REC_EstablishStaticConfigInt32U(initial_window_size, "proxy.config.http2.initial_window_size_in");
>   REC_EstablishStaticConfigInt32U(max_frame_size, "proxy.config.http2.max_frame_size");
>   REC_EstablishStaticConfigInt32U(header_table_size, "proxy.config.http2.header_table_size");
> @@ -751,7 +756,8 @@ Http2::init()
>   REC_EstablishStaticConfigInt32U(active_timeout_in, "proxy.config.http2.active_timeout_in");
>
>   // If any settings is broken, ATS should not start
> -  ink_release_assert(http2_settings_parameter_is_valid({HTTP2_SETTINGS_MAX_CONCURRENT_STREAMS, max_concurrent_streams}) &&
> +  ink_release_assert(http2_settings_parameter_is_valid({HTTP2_SETTINGS_MAX_CONCURRENT_STREAMS, max_concurrent_streams_in}) &&
> +                     http2_settings_parameter_is_valid({HTTP2_SETTINGS_MAX_CONCURRENT_STREAMS, min_concurrent_streams_in}) &&
>                      http2_settings_parameter_is_valid({HTTP2_SETTINGS_INITIAL_WINDOW_SIZE, initial_window_size}) &&
>                      http2_settings_parameter_is_valid({HTTP2_SETTINGS_MAX_FRAME_SIZE, max_frame_size}) &&
>                      http2_settings_parameter_is_valid({HTTP2_SETTINGS_HEADER_TABLE_SIZE, header_table_size}) &&

This should be multiple ink_release_asserts, otherwise it will be difficult to figure out which one failed.
Yes, it should be. I'll fix.
 

>
> http://git-wip-us.apache.org/repos/asf/trafficserver/blob/0e6e5c15/proxy/http2/HTTP2.h
> ----------------------------------------------------------------------
> diff --git a/proxy/http2/HTTP2.h b/proxy/http2/HTTP2.h
> index 10e22e3..9b62b17 100644
> --- a/proxy/http2/HTTP2.h
> +++ b/proxy/http2/HTTP2.h
> @@ -342,7 +342,10 @@ int64_t http2_write_header_fragment(HTTPHdr *, MIMEFieldIter &, uint8_t *, uint6
> class Http2
> {
> public:
> -  static uint32_t max_concurrent_streams;
> +  static uint32_t max_concurrent_streams_in;
> +  static uint32_t min_concurrent_streams_in;
> +  static uint32_t max_active_streams_in;
> +  static bool throttling;
>   static uint32_t initial_window_size;
>   static uint32_t max_frame_size;
>   static uint32_t header_table_size;
>
> http://git-wip-us.apache.org/repos/asf/trafficserver/blob/0e6e5c15/proxy/http2/Http2ConnectionState.cc
> ----------------------------------------------------------------------
> diff --git a/proxy/http2/Http2ConnectionState.cc b/proxy/http2/Http2ConnectionState.cc
> index 077f8ea..5180b3f 100644
> --- a/proxy/http2/Http2ConnectionState.cc
> +++ b/proxy/http2/Http2ConnectionState.cc
> @@ -727,6 +727,8 @@ Http2ConnectionState::main_event_handler(int event, void *edata)
>     // settings.
>     Http2ConnectionSettings configured_settings;
>     configured_settings.settings_from_configs();
> +    configured_settings.set(HTTP2_SETTINGS_MAX_CONCURRENT_STREAMS, _adjust_concurrent_stream());
> +
>     send_settings_frame(configured_settings);
>
>     if (server_settings.get(HTTP2_SETTINGS_INITIAL_WINDOW_SIZE) > HTTP2_INITIAL_WINDOW_SIZE) {
> @@ -1167,3 +1169,36 @@ Http2ConnectionState::send_window_update_frame(Http2StreamId id, uint32_t size)
>   SCOPED_MUTEX_LOCK(lock, this->ua_session->mutex, this_ethread());
>   this->ua_session->handleEvent(HTTP2_SESSION_EVENT_XMIT, &window_update);
> }
> +
> +// Return min_concurrent_streams_in when current client streams number is larger than max_active_streams_in.
> +// Main purpose of this is preventing DDoS Attacks.
> +unsigned
> +Http2ConnectionState::_adjust_concurrent_stream()
> +{
> +  if (Http2::max_active_streams_in == 0) {
> +    // Throttling down is disabled.
> +    return Http2::max_concurrent_streams_in;
> +  }
> +
> +  int64_t current_client_streams = 0;
> +  RecGetRawStatSum(http2_rsb, HTTP2_STAT_CURRENT_CLIENT_STREAM_COUNT, &current_client_streams);
> +
> +  DebugHttp2Con(ua_session, "current client streams: %" PRId64, current_client_streams);
> +
> +  if (current_client_streams >= Http2::max_active_streams_in) {
> +    if (!Http2::throttling) {
> +      Warning("too many streams: %" PRId64 ", reduce SETTINGS_MAX_CONCURRENT_STREAMS to %d", current_client_streams,
> +              Http2::min_concurrent_streams_in);
> +      Http2::throttling = true;
> +    }
> +
> +    return Http2::min_concurrent_streams_in;
> +  } else {
> +    if (Http2::throttling) {
> +      Note("revert SETTINGS_MAX_CONCURRENT_STREAMS to %d", Http2::max_concurrent_streams_in);

I’m not sure that we want to log these. Consider a throttling metric instead?
throttling metric? Would you give me more details?

ATS logs "too many connections, throttling" when connections are over proxy.config.net.connections_throttle. I followed this.
 

> +      Http2::throttling = false;
> +    }
> +  }
> +
> +  return Http2::max_concurrent_streams_in;
> +}
>
> http://git-wip-us.apache.org/repos/asf/trafficserver/blob/0e6e5c15/proxy/http2/Http2ConnectionState.h
> ----------------------------------------------------------------------
> diff --git a/proxy/http2/Http2ConnectionState.h b/proxy/http2/Http2ConnectionState.h
> index 9423c4e..afd0cf2 100644
> --- a/proxy/http2/Http2ConnectionState.h
> +++ b/proxy/http2/Http2ConnectionState.h
> @@ -51,7 +51,7 @@ public:
>   void
>   settings_from_configs()
>   {
> -    settings[indexof(HTTP2_SETTINGS_MAX_CONCURRENT_STREAMS)] = Http2::max_concurrent_streams;
> +    settings[indexof(HTTP2_SETTINGS_MAX_CONCURRENT_STREAMS)] = Http2::max_concurrent_streams_in;
>     settings[indexof(HTTP2_SETTINGS_INITIAL_WINDOW_SIZE)] = Http2::initial_window_size;
>     settings[indexof(HTTP2_SETTINGS_MAX_FRAME_SIZE)] = Http2::max_frame_size;
>     settings[indexof(HTTP2_SETTINGS_HEADER_TABLE_SIZE)] = Http2::header_table_size;
> @@ -199,6 +199,8 @@ private:
>   Http2ConnectionState(const Http2ConnectionState &);            // noncopyable
>   Http2ConnectionState &operator=(const Http2ConnectionState &); // noncopyable
>
> +  unsigned _adjust_concurrent_stream();
> +
>   // NOTE: 'stream_list' has only active streams.
>   //   If given Stream Identifier is not found in stream_list and it is less
>   //   than or equal to latest_streamid, the state of Stream
>