Mark Thanks for taking the time to answer my questions. Please see my response and questions below.
-----Original Message----- From: Mark Thomas [mailto:ma...@apache.org] Sent: Thursday, July 14, 2016 2:58 PM To: Tomcat Users List Subject: Re: OutOfMemoryError: PermGen space > On 14/07/2016 20:26, Berneburg, Cris wrote: > > > Hi Folks > > > > I got this error from the Tomcat Web Application Manager after having > > stopped and started one of the applications multiple times. (This was > > after repeatedly deploying the application manually to attempt to find > > a bug that I could not reproduce in my IDE.) Once the error occurred, > > the server was extremely sluggish to respond even to remote desktop > > mouse and keyboard events. > > > > [SNIP] > > > > Here's the error: > > > > FAIL - Application at context path /someapp could not be started FAIL > > - Encountered exception java.lang.OutOfMemoryError: PermGen space > > > > Is this likely due to a memory leak in my application? > > Yes. > > > Or does it have something to do with me doing so many repeated deployments? > > Also yes. > > > Or perhaps simply from restarting the app so many times? > > Stop/start has the same effect as redeploy in this case. > > > I might try an experiment to see how many times I can stop/start the > > app before the error next occurs. > > > > OS: Win Server 2012 R2 > > Java: 1.6.0_24 (oops, need to upgrade that now) > > Tomcat: 6.0.37 (hmm... will need to upgrade soon-ish) > > Indeed. Some upgrades are certainly in order. Not least because some of > the potential sources of memory leaks are JVM bugs that are fixed in > the lastest Java 8 releases. > > This is probably a useful read: > http://people.apache.org/~markt/presentations/2010-11-04-Memory-Leaks-60mins.pdf > > Despite the age, it is still very relevant today. Thanks for reminding me about that document. It does sound relevant. The document says, > How memory leaks occur: Reference chains > [...] > Retaining a reference to a single object from a web application > pins every class loaded by the web application in the Permanent > Generation Practically speaking, how is a reference retained? 1. Is a module-level (member) variable in a Servlet an example? 2. How about using ServletContext.setAttribute without an accompanying removeAttribute? 3. I see in one of my listeners some member (module-level) variables: a private static for the logger and also a protected final String. Is that a problem? If you could provide a little more guidance about the details, I would appreciate it. > Mark -- Cris Berneburg, Lead Software Engineer, CACI --------------------------------------------------------------------- To unsubscribe, e-mail: users-unsubscr...@tomcat.apache.org For additional commands, e-mail: users-h...@tomcat.apache.org
