For our long-running clojure server app, I found that adding `:jvm-opts ["-server"]` to the project.clj increased performance a bit. It's too much info for this post, but hers'a good description from SO: http://stackoverflow.com/questions/198577/real-differences-between-java-server-and-java-client.
On Monday, October 22, 2012 2:30:48 PM UTC-4, larry google groups wrote: > > > I am fairly new to Clojure, and new to the JVM, so I do not know how to > diagnose a dying app. > > I have a very simple app that tries to keep track (in memory) of who is > logged in. I'll show the code below. I compiled this app and uploaded it to > my server and launched it like this: > > who-is-logged-in-1.0.1-standalone.jar 40000 </dev/null >/dev/null 2>&1 & > > This ran for a day or two, and then it died. I restarted it, and it ran > another day or 2, and then it died. I just restarted it so you might be > able to see its output here: > > http://www.tailormadeanswers.com:40000/ > > What you see is from some Javascript, which works when people log into a > site like this: > > http://www.wpquestions.com/ > > On that site, the Javascript sends an Ajax ping every 10 seconds. The > Clojure app remembers everyone who has sent a ping during the last 15 > seconds. I don't think this has ever been more than 30 people, so I doubt > that I am at risk of exhausting the memory. If the app is running, you can > see some usage stats here: > > http://www.tailormadeanswers.com:40000/show-resources > > I have not yet added any security to the app, so there is a chance that > someone is shutting it down with spam. (I just got this app up last week, > and was planning to add security checks this week). > > I do not know much about programming for the JVM, so I am curious, how do > I diagnose this? I could add some logging, but what should I log? What > should I be looking for? > > My project.clj looks like this: > > (defproject who-is-logged-in "1.0.1" > :description "When users arrive at a site like wpquestions.com, and > then log in, the Javascript on that site should do 2 things: ping this > software to let us know that user has logged in, and also ping this > software to get some info about who else is logged in. The Javascript on > the site should be able to take the data this software sends and turn it > into a meaningful list of logged in users. Version: 1.0.1: since the output > needs to be consumed by Javascript as JSON, I'm making some changes in the > way the registry outputs." > :dependencies [[org.clojure/clojure "1.3.0"] > [net.cgrand/moustache "1.1.0"] > [ring "1.1.5"] > [ring/ring-jetty-adapter "1.1.5"] > [org.clojure/data.json "0.2.0"]] > :main who-is-logged-in.core > :jvm-opts ["-Xmx4000m"]) > > > And the core.clj looks like this: > > (ns who-is-logged-in.core > (:gen-class) > (:import (java.util Date)) > (:require clojure.string clojure.java.io who-is-logged-in.memory_display > [clojure.data.json :as json]) > (:use [net.cgrand.moustache :only [app delegate]] > [ring.util.response] > [ring.middleware.params] > [ring.adapter.jetty :only [run-jetty]])) > > (def registry (atom {})) > > (defn add-to-logged-in-registry [this-users-params] > "We assume some user is looking at a site such as wpquestions.com and > the Javascript on that site is sending an Ajax request to this app, every > 10 seconds, with a map of information about the user, which we need to > store in the registry." > (let [right-now (. (Date.) getTime) > new-user-entry (conj this-users-params { "updated" right-now })] > (if-not (nil? (get new-user-entry "username")) > (swap! registry assoc (get new-user-entry "username") > new-user-entry)))) > > (defn is-current? [this-users-map] > "If we have not received an Ajax request from a user during the last 15 > seconds then we can assume they have left the site. We need to remove them > from registry." > (let [most-recent-ping (get this-users-map "updated") > allowed-cutoff (- (. (Date.) getTime) 15000)] > (if (> most-recent-ping allowed-cutoff) > true > false))) > > (defn remove-old-registrants [] > "The registry should only show people who have pinged this app during > the last 15 seconds. We rebuild the registry with only those users whose > maps return true from is-current?" > (def updated-registry {}) > (swap! registry (fn [map-of-all-user-maps] > (into {} > (doall > (for [[username-as-key each-user-map] > map-of-all-user-maps :when (is-current? each-user-map)] > (conj updated-registry {(get each-user-map > "username") each-user-map}))))))) > > (defn current-users [request] > "The default action of this app. Add new users to the registry, and > delete the ones that are more than 15 seconds old" > (let [this-users-params (:params request)] > (add-to-logged-in-registry this-users-params) > (remove-old-registrants) > (response (apply str (json/write-str @registry))))) > > > > > > > > > > > -- You received this message because you are subscribed to the Google Groups "Clojure" group. To post to this group, send email to clojure@googlegroups.com Note that posts from new members are moderated - please be patient with your first post. To unsubscribe from this group, send email to clojure+unsubscr...@googlegroups.com For more options, visit this group at http://groups.google.com/group/clojure?hl=en
