Inexplicable NumberFormatException in appengine java application

[Nicanor Babula]

Hello,

Today, our application started raising inexplicable NumberFormatExceptions out of nothing and for no obvious reason. Also, it is unable to identify the cause, the stack trace doesn't point to any of our application's code.

Here is the stack trace:

[code]

Uncaught exception from servlet
javax.servlet.UnavailableException: java.lang.NumberFormatException: null
	at org.mortbay.jetty.servlet.ServletHolder.makeUnavailable(ServletHolder.java:415)
	at org.mortbay.jetty.servlet.ServletHolder.initServlet(ServletHolder.java:458)
	at org.mortbay.jetty.servlet.ServletHolder.getServlet(ServletHolder.java:339)
	at org.mortbay.jetty.servlet.ServletHolder.handle(ServletHolder.java:487)
	at org.mortbay.jetty.servlet.ServletHandler$CachedChain.doFilter(ServletHandler.java:1166)
	at cri.domodentweb.server.servlets.ACLFilter.doFilter(ACLFilter.java:56)
	at org.mortbay.jetty.servlet.ServletHandler$CachedChain.doFilter(ServletHandler.java:1157)
	at cri.domodentweb.server.servlets.AccountStatsFilter.doFilter(AccountStatsFilter.java:61)
	at org.mortbay.jetty.servlet.ServletHandler$CachedChain.doFilter(ServletHandler.java:1157)
	at cri.domodentweb.server.servlets.GWTCacheControlFilter.doFilter(GWTCacheControlFilter.java:62)
	at org.mortbay.jetty.servlet.ServletHandler$CachedChain.doFilter(ServletHandler.java:1157)
	at com.google.apphosting.utils.servlet.ParseBlobUploadFilter.doFilter(ParseBlobUploadFilter.java:125)
	at org.mortbay.jetty.servlet.ServletHandler$CachedChain.doFilter(ServletHandler.java:1157)
	at com.google.apphosting.runtime.jetty.SaveSessionFilter.doFilter(SaveSessionFilter.java:35)
	at org.mortbay.jetty.servlet.ServletHandler$CachedChain.doFilter(ServletHandler.java:1157)
	at com.google.apphosting.utils.servlet.JdbcMySqlConnectionCleanupFilter.doFilter(JdbcMySqlConnectionCleanupFilter.java:57)
	at org.mortbay.jetty.servlet.ServletHandler$CachedChain.doFilter(ServletHandler.java:1157)
	at com.google.apphosting.utils.servlet.TransactionCleanupFilter.doFilter(TransactionCleanupFilter.java:43)
	at org.mortbay.jetty.servlet.ServletHandler$CachedChain.doFilter(ServletHandler.java:1157)
	at org.mortbay.jetty.servlet.ServletHandler.handle(ServletHandler.java:388)
	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:418)
	at com.google.apphosting.runtime.jetty.AppVersionHandlerMap.handle(AppVersionHandlerMap.java:266)
	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$RequestHandler.headerComplete(HttpConnection.java:923)
	at com.google.apphosting.runtime.jetty.RpcRequestParser.parseAvailable(RpcRequestParser.java:76)
	at org.mortbay.jetty.HttpConnection.handle(HttpConnection.java:404)
	at com.google.apphosting.runtime.jetty.JettyServletEngineAdapter.serviceRequest(JettyServletEngineAdapter.java:146)
	at com.google.apphosting.runtime.JavaRuntime$RequestRunnable.run(JavaRuntime.java:438)
	at com.google.tracing.TraceContext$TraceContextRunnable.runInContext(TraceContext.java:480)
	at com.google.tracing.TraceContext$TraceContextRunnable$1.run(TraceContext.java:487)
	at com.google.tracing.TraceContext.runInContext(TraceContext.java:774)
	at com.google.tracing.TraceContext$DoInTraceContext.runInContext(TraceContext.java:751)
	at com.google.tracing.TraceContext$AbstractTraceContextCallback.runInInheritedContextNoUnref(TraceContext.java:342)
	at com.google.tracing.TraceContext$AbstractTraceContextCallback.runInInheritedContext(TraceContext.java:334)
	at com.google.tracing.TraceContext$TraceContextRunnable.run(TraceContext.java:484)
	at com.google.apphosting.runtime.ThreadGroupPool$PoolEntry.run(ThreadGroupPool.java:251)
	at java.lang.Thread.run(Thread.java:722)

[/code]

This is not the first time we're seeing this errors out of nothing.

Please, could some one help us identify the cause of the problem? Anyone had this problem?

appid: domodentweb2 (version 14e)

sdk: 1.7.6 - java

datastore: HRD

Thanks,

Cristian

www.domodent.it/en/

[Vinny P]

Hi Nicanor.

The source code for org.mortbay.jetty.servlet.ServletHolder is here: http://grepcode.com/file/repo1.maven.org/maven2/org.mortbay.jetty/jetty/6.1.7/org/mortbay/jetty/servlet/ServletHolder.java/  . Of course, the problem is that I don't know what version of Jetty that AppEngine production uses, so this is harder than just looking at source code. 

My educated guess is that a servlet (either your servlet or the framework's servlet) is failing to initialize for some reason (ServletHolder manages the initialization and run of your servlet, which is why it's called a Holder). Due to the failure to initialize, the initServlet method is calling makeUnavailable to signal that the servlet cannot accept any requests. What is your code doing during initialization? You may need to investigate it, and perhaps move code out of your init.

-----------------

-Vinny P

Technology & Media Advisor

Chicago, IL

@GOV on AppDotNet: https://alpha.app.net/gov

[Nicanor Babula]

In fact, you were right. There were a couple of servlets that failed to initialize due to a NumberFormatException. I had to go back in the logs, just before the exception mentioned earlier started to happen.

Thank you for your answer.
Regards,
Cristian

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[Vinny P]

On Saturday, April 13, 2013 3:14:09 PM UTC-5, Nicanor Babula wrote:

In fact, you were right. There were a couple of servlets that failed to initialize due to a NumberFormatException. I had to go back in the logs, just before the exception mentioned earlier started to happen.

Thank you for your answer.
Regards,
Cristian

Good to hear! I love happy endings!

Have a good weekend,

-Vinny