I think, I found something.
The problem seems to be the head request. Normaly you do a HEAD and close
the connection, but in my case it stays open and the http server gets stuck
in an endless loop.
The culprits are:
procedure THttpConnection.SendDocument(SendType : THttpSendType;const
CustomHeaders : String);
and
procedure THttpConnection.ConnectionDataSent(Sender : TObject; Error :
WORD);
In SendDocument the fdocsize gets set to the size of the stream and a
if SendType = httpSendHead then
FDocStream.Seek(0, soFromEnd)
And
if SendType = httpSendDoc then
SendStream
else
Send(nil, 0); { Added 15/04/02 } // this one triggers the
ConnectionDataSent.
In ConnectionDataSent FDataSent >= FDocSize is the end trigger but
ToSend := FDocSize - FDataSent; //fdatasent = 0
if ToSend > FSndBlkSize then
ToSend := FSndBlkSize;
Count := FDocStream.Read(FDocBuf^, ToSend); // =0 because of
FDocStream.Seek(0, soFromEnd) in SendDocument
FDataSent := FDataSent + Count; { Count data which is sent
} // 0 + 0 = 0
if State = wsConnected then { Be sure to be still connected...
}
Send(FDocBuf, Count); { before actually send any data.
} // starts it all over again...
Maybe a
if (FDataSent >= FDocSize) or (FDocStream.Position=FDocStream.Size) then
begin
might be a solution, but I don't know enough of the inner workings of the
http component to foresee possible side effects...
Lars
> -----Original Message-----
> From: [email protected]
> [mailto:[email protected]] On Behalf Of Lars Gehre
> Sent: Thursday, June 30, 2011 9:49 PM
> To: 'ICS support mailing'
> Subject: Re: [twsocket] HTTP Server creates extremly high CPU load
>
> Well I was a little to fast with my conclusion. It only
> happens to files in the demo because they have a proper
> header, the virtual documents only give a 404 for a HEAD request.
>
> The download is not of matter, the demo files are 500 bytes
> or so. And the server load stays as long as the client is connected.
>
> As I said, I was able to replicate this on two different
> machines and it is not limited to local access. cross tests
> between the machines also show this behaviour.
>
> Lars
>
>
> > -----Original Message-----
> > From: [email protected]
> > [mailto:[email protected]] On Behalf Of Arno Garrels
> > Sent: Thursday, June 30, 2011 3:49 PM
> > To: ICS support mailing
> > Subject: Re: [twsocket] HTTP Server creates extremly high CPU load
> >
> > Lars Gehre wrote:
> > > I noticed one thing: This only happens if files are involved, for
> > > virtual documents it does not happen.
> >
> > I cannot reproduce it, 0.0% CPU here.
> > I used the OverbyteIcsWebServ demo running on a Win7 quadcore.
> > However if I download a file with Firefox (100 Mbit/s LAN)
> at around 6
> > MB/s CPU 0 uses ~25-30% and CPU 2 8-15%, overall usage of
> the server
> > process ~8-10% reported by Process Explorer.
> >
> > --
> > Arno Garrels
> >
> >
> >
> > >
> > > For the http server demo it means you need to open Index.html or
> > > Form.html.
> > >
> > > Lars
> > >
> > >> -----Original Message-----
> > >> From: [email protected]
> > >> [mailto:[email protected]] On Behalf Of Lars Gehre
> > >> Sent: Thursday, June 30, 2011 11:21 AM
> > >> To: 'ICS support mailing'
> > >> Subject: [twsocket] HTTP Server creates extremly high CPU load
> > >>
> > >> Hello all,
> > >>
> > >> I have a serious problem with the http server component from
> > >> ICS7 (downloaded from the repository last week).
> > >>
> > >> I'm using the wininet api on the client side to open a (GET)
> > >> connection to a ICS http Server.
> > >> For certain reasons I need to query the HEAD in intervals (while
> > >> the other get is still in progress).
> > >> As soon as I send the second request the CPU load of the http
> > >> server maxes out one CPU core.
> > >>
> > >> Steps to reproduce:
> > >>
> > >> - Run the http server demo from ics.
> > >>
> > >> - Download the demo
> > >> www.dvbviewer.tv/icsproblem/icsproblem.zip source (delphi 7)
> > >>
> > >> - Run the demo, enter the url of the demo server and press the
> > >> button.
> > >>
> > >> - As soon as the call to GetFileSize is finished you see the CPU
> > >> load of the webserver going up.
> > >>
> > >>
> > >> I checked it on two windows 7 (multicore) machines with the same
> > >> result.
> > >>
> > >> I also checked it against several other http servers and none of
> > >> them had a problem with this kind of usage.
> > >>
> > >>
> > >> Thanks
> > >> Lars
> > >>
> > >> --
> > >> To unsubscribe or change your settings for TWSocket mailing list
> > >> please goto
> > >> http://lists.elists.org/cgi-bin/mailman/listinfo/twsocket
> > >> Visit our website at http://www.overbyte.be
> > --
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> >
>
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