On Thu, 31 Mar 2011 16:51:20 -0400 Stuart Halloway <stuart.hallo...@gmail.com> wrote:
> > This is just *strange*. I'm working on converting a servlet that has > > hardwired vectors of values to read those values from a > > database. Given that this is simple, I'm using clojure.contrib.sql and > > an sqlite plugin. Those vectors get walked in the init code to create > > the hashmap that drives page rendering and any actions the servlet takes. > > > > The code change plan is: > > 1a) Convert vector of vector of strings to vector of hashmaps from > > keyword to strings. > > 1b) Tweak processing function in walk call to use :keys to destructure > > instead of vector destructuring. > > 2) Test and commit these changes. > > 3) Replace reference to hardwired vectors with call to > > with-query-results to read in essentially the same data. > > 4) Test and commit these changes. > > > > Ok, I started with a working servlet. I started seeing oddball > > tracebacks after after doing steps 1a & 1b - no new libraries > > involved. I can reproducibly but get tracebacks, but some parts of the > > servlet work fine. The tracebacks look like: > > > > java.lang.RuntimeException: java.lang.NullPointerException > > at clojure.lang.LazySeq.sval(LazySeq.java:47) > > at clojure.lang.LazySeq.seq(LazySeq.java:56) > > at clojure.lang.RT.seq(RT.java:450) > > at clojure.core$seq.invoke(core.clj:122) > > at clojure.core$r.invoke(core.clj:793) > > at clojure.core$reverse.invoke(core.clj:806) > > at clj_stacktrace.core$trim_redundant.invoke(core.clj:86) > > at clj_stacktrace.core$parse_cause_exception.invoke(core.clj:104) > > at clj_stacktrace.core$parse_exception.invoke(core.clj:122) > > at ring.middleware.stacktrace$html_ex_view.invoke(stacktrace.clj:25) > > at > > ring.middleware.stacktrace$html_ex_response.invoke(stacktrace.clj:40) > > at ring.middleware.stacktrace$ex_response.invoke(stacktrace.clj:51) > > at > > ring.middleware.stacktrace$wrap_stacktrace$fn__1571.invoke(stacktrace.clj:61) > > at > > ring.util.servlet$make_service_method$fn__1842.invoke(servlet.clj:117) > > at x10.war$_service.invoke(war.clj:19) > > at x10.war.service(Unknown Source) > > at > > org.mortbay.jetty.servlet.ServletHolder.handle(ServletHolder.java:511) > > at > > org.mortbay.jetty.servlet.ServletHandler.handle(ServletHandler.java:390) > > at > > org.mortbay.jetty.security.SecurityHandler.handle(SecurityHandler.java:216) > > at > > org.mortbay.jetty.servlet.SessionHandler.handle(SessionHandler.java:182) > > at > > org.mortbay.jetty.handler.ContextHandler.handle(ContextHandler.java:765) > > at > > org.mortbay.jetty.webapp.WebAppContext.handle(WebAppContext.java:440) > > at > > org.mortbay.jetty.handler.ContextHandlerCollection.handle(ContextHandlerCollection.java:230) > > at > > org.mortbay.jetty.handler.HandlerCollection.handle(HandlerCollection.java:114) > > at > > org.mortbay.jetty.handler.HandlerWrapper.handle(HandlerWrapper.java:152) > > at org.mortbay.jetty.Server.handle(Server.java:326) > > at > > org.mortbay.jetty.HttpConnection.handleRequest(HttpConnection.java:542) > > at > > org.mortbay.jetty.HttpConnection$RequestHandler.headerComplete(HttpConnection.java:926) > > at org.mortbay.jetty.HttpParser.parseNext(HttpParser.java:549) > > at org.mortbay.jetty.HttpParser.parseAvailable(HttpParser.java:212) > > at org.mortbay.jetty.HttpConnection.handle(HttpConnection.java:404) > > at > > org.mortbay.io.nio.SelectChannelEndPoint.run(SelectChannelEndPoint.java:410) > > at > > org.mortbay.thread.QueuedThreadPool$PoolThread.run(QueuedThreadPool.java:582) > > [Speculation elided...] > > Ok, maybe it's a threading/agent issue. That would explain the "once > > but never again" behavior, if the agent got into the FAILED > > state. Could that corrupt something that might make jetty and/or ring > > fail as above? Except then why do the pages that just render HTML and > > not send work to the agent still work? Grrr. > > > > Anyone got any clue bits (any at all) I can borrow? > Hi Mike, > > It appears that you aren't seeing the actual error (whatever it may be) > because of a bug in clj_stacktrace. That was enough of a hint to chase the problem down: the agent was failing, for two reasons. One was a code bug. The other (which caused it to be erratic) was that it is serializing access to a reusable resource, and if I left the resource opened in the REPL, the agent would fail. That's what caused the erratic behavior that was driving me nuts. Thanks, <mike -- Mike Meyer <m...@mired.org> http://www.mired.org/consulting.html Independent Software developer/SCM consultant, email for more information. 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