> From: lightbulb432 [mailto:[EMAIL PROTECTED] > Subject: RE: Is ThreadLocal safe to use in servlets > > Based on the behavior you specified of ThreadLocals sticking > around after the webapp is undeployed, is it correct to say > that the thread pool you mentioned is global to ALL webapps > in Tomcat, rather than multiple thread pools, one for each > webapp in the same Tomcat instance?
Normally, there's a thread pool per <Connector>. Tomcat 6 introduces the ability to share thread pools across multiple <Connector>s, via the <Executor> element. (I haven't tried it.) > Is it also correct to say that this could be a security > problem, where a user in another webapp could inadvertently > see something left around in a ThreadLocal from another user > in the same webapp - or from another user in a different webapp? Yes, that's another reason to restrict the lifetime to that of a single request. Exposure across webapps would be difficult to exploit unless the class definition of the object cached via ThreadLocal were visible to both webapps. > Do you see any problems with creating one or more > ThreadLocals as the first operation in the first > filter defined for a webapp, and closing them (i.e. > nulling them out) as the last operation in that same > filter? Should be o.k., and there's shouldn't be any GC impacts. > But am I correct to say that it's a limitation that session > listeners (both attribute-binding and creational listener > methods) aren't guaranteed to be run in the same thread as > the request that created it? AFAIK, there's no guarantee, since the servlet spec doesn't appear to require it. I haven't looked at the Catalina code to see how such Listeners are actually invoked, but it would seem rather risky to count on the same thread being used. > After all, each of those operations happens directly because > of and "in" a given request, so wouldn't it be a better design > for those methods to be called by the same thread? Such a requirement might be better from performance reasons, but it would be restrictive on the container implementation. After all, ThreadLocal is an abusable nicety, not an intrinsic characteristic of servlet processing. - Chuck THIS COMMUNICATION MAY CONTAIN CONFIDENTIAL AND/OR OTHERWISE PROPRIETARY MATERIAL and is thus for use only by the intended recipient. If you received this in error, please contact the sender and delete the e-mail and its attachments from all computers. --------------------------------------------------------------------- To start a new topic, e-mail: users@tomcat.apache.org To unsubscribe, e-mail: [EMAIL PROTECTED] For additional commands, e-mail: [EMAIL PROTECTED]
