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THttpServer enhancements

- changed ThreadPoolContentionCount into ThreadPoolContentionTime
- introducing KeepAliveTimeOut parameter for constructor
- ServerKeepAliveTimeOut=0 will disable HTTP/1.1 keep alive for this server (handy e.g. behind a nginx reverse proxy)
- fixed bug of stopping process on thread pool contention
- enhanced the associated documentation
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Arnaud Bouchez
Arnaud Bouchez committed Jan 26, 2018
1 parent 29751d0 commit 7c6d09df6caf3d8865e488d9147b5340c1a15fca
Showing with 61 additions and 46 deletions.
  1. +1 −1 SQLite3/mORMotService.pas
  2. +7 −6 SynBidirSock.pas
  3. +52 −38 SynCrtSock.pas
  4. +1 −1
@@ -107,7 +107,7 @@ interface
mORMot; // for TSynJsonFileSettings
mORMot; // for TSynJsonFileSettings (i.e. JSON serialization)
{$ifdef MSWINDOWS}
@@ -987,11 +987,12 @@ TWebSocketServer = class(THttpServer)
// - note that this constructor will not register any protocol, so is
// useless until you execute Protocols.Add()
// - in the current implementation, the ServerThreadPoolCount parameter will
// be ignored, and two threads will handle shortliving HTTP/1.0
// "connection: close" requests, and one thread will be maintained per
// keep-alive/websockets client
// use two threads by default to handle shortliving HTTP/1.0 "connection: close"
// requests, and one thread will be maintained per keep-alive/websockets client
// - by design, the KeepAliveTimeOut=0 value is ignored with this server
constructor Create(const aPort: SockString; OnStart,OnStop: TNotifyThreadEvent;
const ProcessName: SockString; ServerThreadPoolCount: integer=0); override;
const ProcessName: SockString; ServerThreadPoolCount: integer=2;
KeepAliveTimeOut: integer=3000); override;
/// close the server
destructor Destroy; override;
/// will send a given frame to all connected clients
@@ -2790,15 +2791,15 @@ function HttpServerWebSocketUpgrade(ClientSock: THttpServerSocket;
{ TWebSocketServer }
constructor TWebSocketServer.Create(const aPort: SockString; OnStart,OnStop: TNotifyThreadEvent;
const ProcessName: SockString; ServerThreadPoolCount: integer);
const ProcessName: SockString; ServerThreadPoolCount, KeepAliveTimeOut: integer);
fThreadRespClass := TWebSocketServerResp;
fWebSocketConnections := TObjectListLocked.Create(false);
fProtocols := TWebSocketProtocolList.Create;
fSettings.HeartbeatDelay := 20000;
fCanNotifyCallback := true;
inherited Create(aPort,OnStart,OnStop,ProcessName,2); // 2 threads for HTTP/1.0
inherited Create(aPort,OnStart,OnStop,ProcessName,ServerThreadPoolCount,KeepAliveTimeOut);
function TWebSocketServer.WebSocketProcessUpgrade(ClientSock: THttpServerSocket;
@@ -1793,17 +1793,18 @@ TSynWebSocketGuard = class(TThread)
// - a Thread Pool is used internaly to speed up HTTP/1.0 connections - a
// typical use, under Linux, is to run this class behind a NGINX frontend,
// configured as https reverse proxy, leaving default "proxy_http_version 1.0"
// and "proxy_request_buffering on" options for best performance
// - it will trigger the Windows firewall popup UAC window at first run
// - don't forget to use Free procedure when you are finished
// and "proxy_request_buffering on" options for best performance, and
// setting KeepAliveTimeOut=0 in the THttpServer.Create constructor
// - under windows, will trigger the firewall UAC popup at first run
// - don't forget to use Free method when you are finished
THttpServer = class(THttpServerGeneric)
fDisableKeepAliveSupport: boolean;
/// used to protect Process() call
fProcessCS: TRTLCriticalSection;
fThreadPoolPush: TOnThreadPoolSocketPush;
fThreadPoolContentionCount: cardinal;
fThreadPoolContentionTime: cardinal;
fThreadPoolContentionAbortCount: cardinal;
fThreadPoolContentionAbortDelay: cardinal;
fThreadPool: TSynThreadPoolTHttpServer;
fInternalHttpServerRespList: TList;
fServerConnectionCount: cardinal;
@@ -1833,9 +1834,10 @@ THttpServer = class(THttpServerGeneric)
// incoming connections (default is 32, which may be sufficient for most
// cases, maximum is 256) - if you set 0, the thread pool will be disabled
// and one thread will be created for any incoming connection
// - you can also tune (or disable with 0) HTTP/1.1 keep alive delay
constructor Create(const aPort: SockString; OnStart,OnStop: TNotifyThreadEvent;
const ProcessName: SockString; ServerThreadPoolCount: integer=32;
const aDisableKeepAliveSupport: boolean = false); reintroduce; virtual;
KeepAliveTimeOut: integer=3000); reintroduce; virtual;
/// release all memory and handlers
destructor Destroy; override;
/// access to the main server low-level Socket
@@ -1845,17 +1847,15 @@ THttpServer = class(THttpServerGeneric)
// a THttpServerResp thread is created for handling this THttpServerSocket
property Sock: TCrtSocket read fSock;
/// flag to disable HTTP/1.1 keep alive features and fall back to
// HTTP/1.0 compatibility
// - only threads from thread pool will be used to process requests
// when this flag set to true
property DisableKeepAliveSupport: boolean read fDisableKeepAliveSupport;
/// will contain the total number of connection to the server
/// will contain the total number of connections to the server
// - it's the global count since the server started
property ServerConnectionCount: cardinal
read fServerConnectionCount write fServerConnectionCount;
/// time, in milliseconds, for the HTTP.1/1 connections to be kept alive;
// default is 3000 ms
/// time, in milliseconds, for the HTTP/1.1 connections to be kept alive
// - default is 3000 ms
// - setting 0 here (or in KeepAliveTimeOut constructor parameter) will
// disable keep-alive, and fallback to HTTP.1/0 for all incoming requests
// (may be a good idea e.g. behind a NGINX reverse proxy)
// - see THttpApiServer.SetTimeOutLimits(aIdleConnection) parameter
property ServerKeepAliveTimeOut: cardinal
read fServerKeepAliveTimeOut write fServerKeepAliveTimeOut;
@@ -1870,13 +1870,19 @@ THttpServer = class(THttpServerGeneric)
/// the associated thread pool
// - may be nil if ServerThreadPoolCount was 0 on constructor
property ThreadPool: TSynThreadPoolTHttpServer read fThreadPool;
/// number of times there was no availibility in the internal thread pool
// to handle an incoming request
// - this won't make any error, but just delay for 20 ms and try again
property ThreadPoolContentionCount: cardinal read fThreadPoolContentionCount;
/// number of times there an incoming request is rejected due to overload
// - this is an error after 30 seconds of not any process availability
/// milliseconds spent waiting for an available thread in the pool
// - no available thread won't make any error at first, but try again until
// ThreadPoolContentionAbortDelay is reached and the incoming socket aborded
// - if this number is high, consider setting a higher number of threads,
// or profile and tune the Request method processing
property ThreadPoolContentionTime: cardinal read fThreadPoolContentionTime;
/// how many connections were rejected due to thread pool contention
// - disconnect the client socket after ThreadPoolContentionAbortDelay
// - any high number here requires code refactoring of Request method! :)
property ThreadPoolContentionAbortCount: cardinal read fThreadPoolContentionAbortCount;
/// milliseconds delay to reject a connection due to thread pool contention
// - default is 5000, i.e. 5 seconds
property ThreadPoolContentionAbortDelay: cardinal read fThreadPoolContentionAbortDelay;
@@ -5298,12 +5304,11 @@ function THttpServerGeneric.NextConnectionID: integer;
constructor THttpServer.Create(const aPort: SockString; OnStart,
OnStop: TNotifyThreadEvent; const ProcessName: SockString;
ServerThreadPoolCount: integer; const aDisableKeepAliveSupport: boolean);
ServerThreadPoolCount, KeepAliveTimeOut: integer);
fSock := TCrtSocket.Bind(aPort); // BIND + LISTEN
ServerKeepAliveTimeOut := 3000; // HTTP.1/1 KeepAlive is 3 seconds by default
fDisableKeepAliveSupport := aDisableKeepAliveSupport;
fServerKeepAliveTimeOut := KeepAliveTimeOut; // 3 seconds by default
fInternalHttpServerRespList := TList.Create;
// event handlers set before inherited Create to be visible in childs
fOnHttpThreadStart := OnStart;
@@ -5364,7 +5369,7 @@ procedure THttpServer.Execute;
ClientCrtSock: THttpServerSocket;
i: integer;
tix,starttix,aborttix: cardinal;
// THttpServerGeneric thread preparation: launch any OnHttpThreadStart event
@@ -5398,22 +5403,30 @@ procedure THttpServer.Execute;
if Assigned(fThreadPoolPush) then begin
// use thread pool to process the request header, and probably its body
i := 0;
while not fThreadPoolPush(pointer(ClientSock)) do begin
if not fThreadPoolPush(pointer(ClientSock)) then begin
// returned false if there is no idle thread in the pool
if i>=1500 then begin
// could not acquire thread after 1500*20 = 30 seconds timeout
tix := GetTickCount;
starttix := tix;
aborttix := tix+fThreadPoolContentionAbortDelay; // default 5 sec
if tix-starttix<50 then // wait for an available thread
SleepHiRes(1) else
if Terminated then
if fThreadPoolPush(pointer(ClientSock)) then begin
aborttix := 0; // thread pool acquired the client sock
tix := GetTickCount;
until Terminated or (tix>aborttix) or (tix<starttix);
if integer(tix)>0 then
if aborttix<>0 then begin
SleepHiRes(20); // wait a little until a thread is available
if Terminated then begin
exit; // get out of Execute method.
end else
// default implementation creates one thread for each incoming socket
@@ -5982,7 +5995,8 @@ function THttpServerSocket.GetRequest(withBody: boolean=true): boolean;
P := pointer(Command);
GetNextItem(P,' ',fMethod); // 'GET'
GetNextItem(P,' ',fURL); // '/path'
fKeepAliveClient := not fServer.DisableKeepAliveSupport and IdemPChar(P,'HTTP/1.1');
fKeepAliveClient := ((fServer=nil) or (fServer.ServerKeepAliveTimeOut>0)) and
Content := '';
// get headers and content
@@ -6331,7 +6345,7 @@ procedure TSynThreadPoolTHttpServer.Task(aCaller: TSynThread; aContext: Pointer)
if ServerSock.GetRequest(false) then begin
// connection and header seem valid -> process request further
if not fServer.DisableKeepAliveSupport and
if (fServer.ServerKeepAliveTimeOut>0) and
(fServer.fInternalHttpServerRespList.Count<THREADPOOL_MAXWORKTHREADS) and
(ServerSock.KeepAliveClient or
(ServerSock.ContentLength>THREADPOOL_BIGBODYSIZE)) then begin
@@ -1 +1 @@

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