-----BEGIN PGP SIGNED MESSAGE----- Hash: SHA256 André,
On 12/7/12 4:16 AM, André Warnier wrote: > Williams, Nick wrote: >>> -----Original Message----- From: Christopher Schultz >>> [mailto:ch...@christopherschultz.net] Sent: Thursday, December >>> 06, 2012 5:08 PM To: Tomcat Users List Subject: Re: Is it >>> possible to expire jvmRoute cookie >>> >>>> 2. How one additional user can be a problem in such a system? >>>> If he accesses a heavy-loaded system the things will be slow >>>> for him, but faster for all others, who close their browsers >>>> regularly. >>> Let's take a pathological example: >>> >>> Assumptions: 1. Cluster has 3 nodes (A, B, C) 2. Users never >>> close their browsers >>> >>> Let's say that server A is rock-solid and never goes down. >>> Servers B and C are running Gentoo Linux or Debian Sid or >>> Microsoft Windows or have flaky hardware and so they crash or >>> need to be rebooted all the time; perhaps daily. >>> >>> Users on nodes B and C will constantly fail-over to node A. >>> >>> Those users will stick on node A pretty much forever. >>> >>> Therefore node A always gets most of the traffic, and nodes B >>> and C only get "new" users for a while before failing-over. >>> Even if nodes B and C can handle 1/3 of the load, they will get >>> much less than that, and node A will, over time, accumulate >>> users without bound. >>> >>> It would be nice to avoid this kind of situation. >>> >>>> So one could recommend that if things go slow to close one's >>>> browser, clean caches, or even reboot. ;) >> >> "If I called tech support for a website and they told me I needed >> to close my browser or reboot my computer to just to use their >> website, I would assume that they were complete idiots. If I want >> to be lied to about what the problem is, I'll call my home >> broadband provider." <-- HAHAHA ... nice one. >> >> I agree with Chris, here. It's not a "common" situation, but it >> is a possible situation, and if it occurred, it could get ugly >> quickly. >> >> Earlier somebody (I'm sorry, I already deleted the email) >> suggested Tomcat returning a 308 or 309 or similar to the load >> balancer to trigger a "re-balance" if the session is expired. I >> think this is the best idea I've heard yet, solves the problem >> elegantly and simply, and seems (relatively) easy to achieve >> (this coming from someone who has no knowledge of the code used >> by mod_jk/isapi_redirector). >> > > I must admit that this sounds more elegant (and efficient) than my > suggested interceptor module. > > Alternatively, if one wanted to avoid touching mod_jk for this, > maybe tomcat could return a 302 redirect to the starting page of > this application, if known ? (without jsessionid.jvmroute of > course). That's definitely an idea worth pursuing: an expired session id could return 302 *and* strip the jsessionid path parameter *and* send a Set-Cookie JSESSIONID; expiration=0 header (which deletes the cookie). The client would re-try and the balancer would re-balance. Konstantin, what do you think? Obviously, this shouldn't be the default operation of Tomcat, but perhaps a setting that could be enabled on the session manager? - -chris -----BEGIN PGP SIGNATURE----- Version: GnuPG/MacGPG2 v2.0.17 (Darwin) Comment: GPGTools - http://gpgtools.org Comment: Using GnuPG with undefined - http://www.enigmail.net/ iEYEAREIAAYFAlDCIF4ACgkQ9CaO5/Lv0PDJoACgw9Ys1rnye8NK24fFCtZ6x8Dj PKwAn0kws7TwyT6T4qURPbq3vtkXjxWI =2vJC -----END PGP SIGNATURE----- --------------------------------------------------------------------- To unsubscribe, e-mail: users-unsubscr...@tomcat.apache.org For additional commands, e-mail: users-h...@tomcat.apache.org
