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Benx Shen

Preventing Java's java.lang.OutOfMemoryError: PermGen space failure | Eric's Agile Answers - 0 views

jroller.com/...20060623

*i_comment* exception java memory permgen_space runtime

shared by Benx Shen on 22 May 07 - Cached
  • The "OutOfMemoryError: PermGen space" message is normally encountered during development activites where a long-running JVM is asked to load/unload builds.
  • The message is a symptom of an incomplete garbage collection sweep where resources are not properly released upon unload/restart. There is no shortage of debate (Hibernate forum, Sun forum, Spring Framework forum ) regarding which codebase is responsible for this symptom, but the finger of blame has been pointed at CGLIB, Hibernate, Tomcat, and even Sun's JVM.
  • In my experience, the most pain-free method of resolving this issue is to switch from Sun's JDK implementation to BEA's freely available JRockit implementation.
  • ...1 more annotation...
  • On a recent project utilizing Tomcat 5.5.12 with Hibernate, I was plagued with this PermGen error, at times even experiencing it during web-based unit testing. Since making the switch to JRockit, I have not encountered this issue even once.
  • Benx Shen on 22 May 07
     
    又是一位和我一樣都慘遭 "PermGen Space" 錯誤的開發者了！
    很奇怪，為何會發生這樣的錯誤呢？
    其中這篇文章所提到的技術，恰巧都是我現在所發生問題的架構，像是 Hibernate, Spring, Tomcat 等，還有 Sun JVM.... Orz
    比較特別的是，多數提供的解決方式，都是去調整 JVM 的設定（-XX:MaxPermSize=256m）。這位老兄則是採用了 BEA JRockit 版本的 JVM 解決此問題，他表示至少這招對他是管用的！
    不過，軟體開發很多時候都會發生這種「魔咒」，這種狀況底下，就好像一個並無可醫的人，只好嘗試各種偏方了！

  • yahya_khk21121 on 12 Jul 17
Benx Shen

嵌入式Tomcat怎麼能讓Context自動reload-Tomcat-Java - 0 views

www.javaeye.com/19403

*精華* howto reload tomcat

shared by Benx Shen on 25 May 07 - Cached
Benx Shen

分析java.lang.OutOfMemoryError: PermGen space - 0 views

www.javaeye.com/80620

jvm memory permgen_space

shared by Benx Shen on 22 May 07 - Cached
  • 發現很多人把問題歸因於： spring,hibernate,tomcat，因為他們動態產生類,導致JVM中的permanent heap溢出 。然後解決方法眾說紛紜，有人說升級 tomcat版本到最新甚至乾脆不用tomcat。還有人懷疑spring的問題，在spring論壇上討論很激烈，因為spring在AOP時使用CBLIB會動態產生很多類。
  • 於是有人對更基礎的JVM做了檢查，發現了問題的關鍵。原來SUN 的JVM把內存分了不同的區，其中一個就是permenter區用來存放用得非常多的類和類描述。
  • 對這個bug最徹底的解決辦法就是不要用SUN的JDK，而改用BEA的 JRokit.
Benx Shen

Tomcat 實用小技巧-Tomcat-Java - 3 views

www.javaeye.com/48273

developer testing tip tomcat

shared by Benx Shen on 24 May 07 - Cached
Benx Shen

Raible Designs | Proposed Tomcat Enhancement: Add flag to escape JSP's EL by default - 0 views

raibledesigns.com/...ed_tomcat_enhancement_add_flag

jstl tip

shared by Benx Shen on 20 Sep 07 - Cached
  • Hello all, I'm working for a client that's using a proprietary Servlet/JSP-based framework that runs on Tomcat. They have their own custom JSP compiler and they're looking to move to a standard JSP compiler. One of the things their compiler supports is automatic escaping of XML in expressions. For example, ${foo} would be escaped so <body> -> <body>. JSP EL does not do this. It *doesn't* escape by default and instead requires you to wrap your expressions with <c:out/> if you want escaping. I'd like to ask what developers think about adding a flag (similar to trimSpaces in conf/web.xml) that allows users to change the escaping behavior from false to true? I think this is a good option to have as it allows security-conscious organizations to paranoid and escape all content by default. Thanks, Matt
  • Benx Shen on 20 Sep 07
     
    使用 <c:out> 標籤來取代 ${foo} 這種 EL 的寫法，可以自動將內容中的 < > 轉換成 &lt; &gt;
    這樣，可以讓自己的動態網頁內容變得更加安全喔！

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