-----BEGIN PGP SIGNED MESSAGE----- Hash: SHA1 Rainer,
On 5/21/2009 12:21 PM, Rainer Jung wrote: > 2 remarks about all your stress testing efforts: > > A) TIME_WAIT > > When not doing HTTP Keep-Alive, under high load the size of the TCP hash > table and the effectiveness of the system to lookp up TCP connections > can limit the throughput you can reach. More precisely, depending on the > excat way of connection shutdown, you get TIME_WAIT states for the > finished connections (without HTTP Keep Alive it could be one such > connection per request). Most systems get slow, once the number of those > connections reaches somthing arounf 30000. That's fine, but the TIME_WAIT connections should be counted against the process's file limit, should it? At that point, the process has released the connection and the OS is babysitting it through the final stages of TCP shutdown. I understand that, with keepalive disabled, performance will kind of suck. But, I shouldn't be running out of file descriptors. > E.g. if you are doing 2000 requests per second without HTTP Keep Alive > and the combination of web server and stress test tool leads to > TIME_WAITs, after 15 seconds your table size might reach a critical size. Meaning that the kernel can't keep up, or the NIO connector can't keep up? I suspect the latter, because the other tests under the same conditions at least complete... the NIO one appears not to have a chance. Now, I'm running 6 tests and the NIO test is the 5th one, so it's possible that it's just poorly positioned in my test batter. But, since I've observed this failure at essentially the same place each time, I suspect the NIO connector itself is at fault. > Not using HTTP Keep Alive will very likely limit quickly the achievable > throughput when going up in concurrency. I'm willing to accept that, but 40 max connections should not be resulting in hundreds of left-open file descriptors. - -chris -----BEGIN PGP SIGNATURE----- Version: GnuPG v1.4.9 (MingW32) Comment: Using GnuPG with Mozilla - http://enigmail.mozdev.org/ iEYEARECAAYFAkoWlzUACgkQ9CaO5/Lv0PDtKgCfc9ZOaqcHfvdJHD28wZIiwMAq 52EAn3N1Nk3JoqSOcDkjdlsmJ49t+Yfr =FQdw -----END PGP SIGNATURE----- --------------------------------------------------------------------- To unsubscribe, e-mail: users-unsubscr...@tomcat.apache.org For additional commands, e-mail: users-h...@tomcat.apache.org
