Re: [Php-java-bridge-users] java.so module purpose?

[<php...@li...>]

Sorry, seems my attachments were stripped.  Files available at: 
http://vanstaveren.us/~trick/fbsd-nagle-localhost-errorcase/

Cheers,
Patrick


php...@li... wrote:
> [Sorry to  hijack this thread, just replying from a proper email 
> account as my @mintel.com account is using Lotus Notes]
>
> Alright, I've made some good progress here in understanding this bug:
>
> * Grabbed & compiled the test code as on the FreeBSD ML.  Bug 
> reproduced.  Also produced a client fix within the java code using 
> Socket::setTcpNoDelay(true) to bypass Nagle's Algorithm and it proves 
> that this is the socket option that is not being automatically set.
> * Split out the test code into two pieces: a java server which listens 
> for the packet [TestServ.class], java code to act as a client 
> [TestClient.class] and PHP code which does the client end.  I ended up 
> with two PHP implementations in an attempt to reproduce the bug:
> One) which uses fsockopen(...) which is the same socket method that 
> PJB's PHP library uses.  I cannot get this to trigger Nagle's 
> Algorithm.  Inspection using tcpdump shows that the socket created 
> with fsockopen is buffered, so two calls to fwrite (one with a single 
> byte, one with 50 bytes) end up in a single packet as it waits to send 
> data until the socket is closed.  Code attached [fsockopen-client.php]
> Two) which uses the socket_* functions in the PHP Socket extension and 
> a hacky call to socket_set_option to shrink the send buffer size to 1 
> before the first packet ("@") and then expand the buffer size to 51 
> bytes for the second packet.  tcpdump inspection shows that it doesn't 
> produce the exact same size packets as the java code, but it 
> definitely triggers Nagle's Algorithm and the slowdown is roughly the 
> same as the java test client.  Code attached [sockets-client.php]
>
> From there, I sought out to set TCP_NODELAY in PHP:
> * Took a look around the PHP source code in ext/sockets/sockets.c:500+ 
> where the socket options are set.  The PHP constants are [naturally] 
> the same value as whatever the local system has defined for the 
> kernel's integer value of the constant.  TCP_NODELAY on FreeBSD is 
> 0x01.  I added a function call to my sockets-client.php before sending 
> a packet like:
> socket_set_option($sock, SOL_TCP, 0x01, 1); // disable Nagle's Algorithm
> ...and it works like a charm.  Performs like it should.
> * I've patched sockets.c in PHP and recompiled, and now have 
> TCP_NODELAY available in my sockets extension.  Am submitting this 
> patch to PHP for inclusion.  Can now do:
> socket_set_option($sock, SOL_TCP, TCP_NODELAY, 1); // disable Nagle's 
> Algorithm
> ...and again, works like a charm.
>
> Importantly, from the PJB angle: I cannot reproduce the bug with 
> Nagle's Algorithm using the fsockopen socket method (even using fflush 
> to try and force it to send a packet.)  Jost, do you have some PHP 
> code that can reproduce this bug?  I'm really curious.  I'm tempted to 
> say that the buffering used by fsockopen will dodge this bug, but I 
> don't know for sure.  I'm also wondering if the buffering used by 
> fsockopen might actually be incurring an unnecessary (albeit minor) 
> performance penalty on PJB and if the sockets functions might be a 
> wiser choice.  I'm no expert here.
>
> The patch I've written to make TCP_NODELAY available in PHP will fix 
> the bug if we're ever communicating using the sockets extension, but 
> we're using fsockopen.  It's still worth a submit as it might be 
> useful.  I don't know anything about the internals of fsockopen (I'll 
> give the code a read.)  Furthermore there's no method that I can see 
> to set socket options on a stream opened by fsockopen.
>
> Sorry if this is a lot to digest.  Let me know what your thoughts are 
> and most importantly, if you have a way to reproduce this bug using 
> fsockopen in PHP (and thus something that will actually affect PJB.)
>
> Thanks for all your help!
>
> Patrick
>
>
>
>
>
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-- 
Patrick "Trick" van Staveren
http://trick.vanstaveren.us