Persistent Connections

[unjc email]

Hello there,

I have a question about enabling persistent connections in workload.  The
following is how I setup the server and robot in the pg file; as shown,
pconn_use_lmt is set to 1000.


Server S1 = {
    kind = "S101";
    contents      = [ JpgContent: 73.73%, HtmlContent: 11.45%, SwfContent:
13.05%, FlvContent: 0.06%, Mp3Content: 0.01%, cntOther ];
    direct_access = contents;
    addresses = [ '25.57.0.10:9090', '25.57.0.11:9090' ]; // where to
create these server agents
    http_versions = [ "1.0" ];  // newer agents use HTTP/1.1 by default
    pconn_use_lmt = const(1000); // Persistent connections - should tune
this value
};


// Note that this Robot has an undefined request-rate in order to enable a
// best-effort workload.
Robot R = {

    kind = "R101";
    pop_model = { pop_distr = popUnif(); };
    recurrence = 50%;
    req_rate = undef();
    origins = S1.addresses;      // where the origin servers are

    addresses = robotAddrs(authAddrScheme, theBench);
    pconn_use_lmt = const(1000); // Persistent connections - should tune
this value
    open_conn_lmt = 1; // maximum concurrent connections
    http_versions = [ "1.0" ];  // newer agents use HTTP/1.1 by default
};


I examine the tcp streams of tcpdump output from the client machine, in a
single-robot test; although "connection: keep-alive" are found in both
request and respond headers, I see client issue [FIN, ACK]'s every few
(<10) requests, that is way before 1000 requests they make.


GET /w1b7335ec.2b642c95:00000008/t03/_0000413f.jpg HTTP/1.0
Accept: */*
Host: 25.57.0.10:9090
X-Xact: 1b7335ec.2b642c95:00000002 1b7335ec.2b642c95:00020522 0
X-Loc-World: 1b7335ec.2b642c95:00000008 -1/16703 8351
X-Rem-World: 1b7335ec.2b642c95:00000008 -1/16703 8351
X-Target: 25.57.0.10:9090
X-Abort: -324104509 -1205953971
X-Phase-Sync-Pos: 0
Connection: keep-alive

HTTP/1.0 200 OK
Cache-Control: private,no-cache
Pragma: no-cache
Date: Wed, 03 Jul 2013 19:50:22 GMT
Connection: keep-alive
Content-Length: 9479
Content-Type: image/jpeg
X-Target: 25.57.0.10:9090
X-Xact: 1b7335e7.5e615116:00000002 1b7335ec.2b642c95:7ffdfadd 0
X-Rem-World: 1b7335ef.4e10652d:00000008 -1/15998 7999
X-Abort:  2013317368 2072661844
X-Phase-Sync-Pos: 0


I also found the robot machine runs out of ephemeral ports shortly after
the starrt of the single-robot test.  The ulimit value of the machine
is 65536.   I am surprised to see this if the persistent connections are
being used.  FYI, this is non-proxy test.

003.04| EphPortMgr.cc:23: error: 4096/8191 (s98) Address already in use
003.04| OS probably ran out of ephemeral ports at 25.57.100.2:0
003.04| Client.cc:347: error: 4096/8192 (c63) failed to establish a
connection
003.04| 25.57.100.2 failed to connect to 25.57.0.11:9090



Would you please kindly advise what I might configure wrong?



Thanks,
Jacky
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