undefined | Better HN

0 pointsfhood7y ago0 comments

It isn't just a huge hint, most of the time it tells you exactly what the damn issue is. This discussion is blowing my mind.

I am honestly speechless. IT GIVES YOU THE LINE NUMBER AND THE FUNCTION CALL AND THE REASON! Why would you ever even attempt to debug without parsing it?

0 comments

eitland7y ago

Wait wait wait.

Not so fast.

i'm one of those programmers who read manuals and stack traces but I have to admit that I've seen my share of both manuals as well as stack traces that didn't make much sense.

kickopotomus7y ago

This is my experience with Clojure stack traces ~60-75% of the time. Perhaps it is a symptom of functional programming? A lot of function passing and anonymous functions make it difficult to generate a meaningful stack trace.

lmkg7y ago

Clojure's stack traces are an issue with Clojure specifically, and how it's hosted on top of the JVM. A lot of the stack trace you get is actually implementation details of the Java objects making up the Clojure runtime. In effect, the program that you get stack traces of is the Clojure interpreter rather than your Clojure program which is running inside that interpreter.

3 more replies

avhon17y ago

My experience in Racket has been the opposite. Especially with the aid of DrRacket's stepping debugger, reading stack traces and finding bugs is rather painless. (Figuring out the best way to fix bugs, however, is no easier than in any other language.)

quaunaut7y ago

Functional programming not so much- languages like Elixir or JS used functionally don't have this problem generally.

1 more reply

dave_sid7y ago

Yeah I agree. The way this thread is going you would think that all errors are easy and all you have to do is what the computer tells you and you’re done. I wish I’d known it was all that simple!

TimTheTinker7y ago

> stack traces that didn't make much sense.

Those can be especially prevalent in systems that utilize a lot of indirection.

_mdpn7y ago

Especially when you end up in C++ template hell.

NeoBasilisk7y ago

That kind of stuff permanently damaged my ability to enjoy using C++.

samnardoni7y ago

Error in boost/bind.hpp:768

dba7dba7y ago

That's exactly what I felt as I was spending time on MSDN/Microsoft support website, reading about weird errors messages on Windows 95/98/NT/XP in 1990s. Some generic desc about the Windows error messages and no resolution.

tyrex20177y ago

as in tensorflow stack traces

dsr_7y ago

And in the opposite direction: remember when you are writing error messages to include all the relevant details, and never ever write "this shouldn't happen" or "document later".

fhoodOP7y ago

What about, log_panic("If we have somehow managed to hit this code path, this project if FUBAR. I would recommend giving up and starting over.")

btschaegg7y ago

Somehow reminds me of Aliens:

  I say we take off and nuke the entire site from orbit. It's the only way to be sure.

:-)

m_samuel_l7y ago

That's annoying but fine as long as it's unique and you can grep it in the codebase.

1 more reply

pletnes7y ago

If used correctly, «this should not happen» can be very useful, indicating e.g that the program is in some illegal state, as opposed to the input being incorrectly formatted.

scarface747y ago

Even if that’s the case, create a custom exception and embed in the custom exception object the actual exception.

1 more reply

scarface747y ago

That’s only true if the developer of the class module let the entire stack trace get through to the consumer.

In C# it’s the difference between...

try

{

....

}catch(Exception e)

{

//Do stuff

   throw new MyCustomException(“Something Bad happened”);

}

And

try

{

....

}catch(Exception e)

{

  //do stuff

   throw;

}

moron4hire7y ago

Erh, exception types should include an inner exception parameter, for the generic one they wrap. So neither of your two examples are all that great.

scarface747y ago

Why would I wrap an exception if I don’t plan to have special handling? If it is exception that I didn’t throw because of a business reason, why not just throw the original exception?

1 more reply

debaserab27y ago

In what case would you ever want the second example?

orangepenguin7y ago

Always. If you can't resolve the exception and continue processing normally, you should never discard the exception you caught and create a new one of your own. If you must create one of your own, include the one you caught for the additional context.

It's pretty frustrating when you're debugging someone else's code and their error handling just throws away all of the useful information and replaces it with a generic "Something broke" kind of message.

elsombrero7y ago

usually you may catch a general exception and throw another one that's caught up the call stack. In this case i think it may be useful for logging additional causes that are not going to be obvious with just the stacktrace(?)

bmhin7y ago

I remember once encountering an error that had all of the above plus it presented the solution to the issue right in the error message. It was amazing and why I still remember seeing that to this day.

avip7y ago

Let's try that! I was trying to do some trivial task on a .gov website, but was greeted with the following, which I'm pasting here for your convenience. Could you spot the problem? Because their customer service can't.

---

Error Page Exception SRVE0260E: The server cannot use the error page specified for your application to handle the Original Exception printed below.

Original Exception: Error Message: javax.servlet.ServletException: /verification.xhtml at line 66 and column 34 action="#{verificationAction.authenticateClient()}": java.lang.NullPointerException Error Code: 500 Target Servlet: Faces Servlet Error Stack: javax.el.ELException: /verification.xhtml at line 66 and column 34 action="#{verificationAction.authenticateClient()}": java.lang.NullPointerException at org.apache.myfaces.view.facelets.el.TagMethodExpression.invoke(TagMethodExpression.java:95) at javax.faces.component._MethodExpressionToMethodBinding.invoke(_MethodExpressionToMethodBinding.java:88) at org.apache.myfaces.application.ActionListenerImpl.__AW_processAction(ActionListenerImpl.java:100) at org.apache.myfaces.application.ActionListenerImpl.processAction(ActionListenerImpl.java) at javax.faces.component.UICommand.broadcast(UICommand.java:120) at javax.faces.component.UIViewRoot._broadcastAll(UIViewRoot.java:995) at javax.faces.component.UIViewRoot.broadcastEvents(UIViewRoot.java:278) at javax.faces.component.UIViewRoot._process(UIViewRoot.java:1307) at javax.faces.component.UIViewRoot.processApplication(UIViewRoot.java:733) at org.apache.myfaces.lifecycle.InvokeApplicationExecutor.execute(InvokeApplicationExecutor.java:34) at org.apache.myfaces.lifecycle.LifecycleImpl.__AW_executePhase(LifecycleImpl.java:172) at org.apache.myfaces.lifecycle.LifecycleImpl.executePhase(LifecycleImpl.java) at org.apache.myfaces.lifecycle.LifecycleImpl.__AW_execute(LifecycleImpl.java:119) at org.apache.myfaces.lifecycle.LifecycleImpl.execute(LifecycleImpl.java) at javax.faces.webapp.FacesServlet.__AW_service(FacesServlet.java:189) at javax.faces.webapp.FacesServlet.service(FacesServlet.java) at com.ibm.ws.webcontainer.servlet.ServletWrapper.service(ServletWrapper.java:1233) at com.ibm.ws.webcontainer.servlet.ServletWrapper.handleRequest(ServletWrapper.java:782) at com.ibm.ws.webcontainer.servlet.ServletWrapper.handleRequest(ServletWrapper.java:481) at com.ibm.ws.webcontainer.servlet.ServletWrapperImpl.handleRequest(ServletWrapperImpl.java:178) at com.ibm.ws.webcontainer.filter.WebAppFilterChain.invokeTarget(WebAppFilterChain.java:136) at com.ibm.ws.webcontainer.filter.WebAppFilterChain.doFilter(WebAppFilterChain.java:97) at com.icbc.licensing.filter.ThreadContextFilter.__AW_doFilter(ThreadContextFilter.java:92) at com.icbc.licensing.filter.ThreadContextFilter.doFilter(ThreadContextFilter.java) at com.ibm.ws.webcontainer.filter.FilterInstanceWrapper.doFilter(FilterInstanceWrapper.java:195) at com.ibm.ws.webcontainer.filter.WebAppFilterChain.doFilter(WebAppFilterChain.java:91) at org.apache.logging.log4j.web.Log4jServletFilter.__AW_doFilter(Log4jServletFilter.java:71) at org.apache.logging.log4j.web.Log4jServletFilter.doFilter(Log4jServletFilter.java) at com.ibm.ws.webcontainer.filter.FilterInstanceWrapper.doFilter(FilterInstanceWrapper.java:195) at com.ibm.ws.webcontainer.filter.WebAppFilterChain.doFilter(WebAppFilterChain.java:91) at com.ibm.ws.webcontainer.filter.WebAppFilterManager.doFilter(WebAppFilterManager.java:967) at com.ibm.ws.webcontainer.filter.WebAppFilterManager.invokeFilters(WebAppFilterManager.java:1107) at com.ibm.ws.webcontainer.servlet.CacheServletWrapper.handleRequest(CacheServletWrapper.java:87) at com.ibm.ws.webcontainer.WebContainer.handleRequest(WebContainer.java:949) at com.ibm.ws.webcontainer.WSWebContainer.handleRequest(WSWebContainer.java:1817) at com.ibm.ws.webcontainer.channel.WCChannelLink.ready(WCChannelLink.java:200) at com.ibm.ws.http.channel.inbound.impl.HttpInboundLink.handleDiscrimination(HttpInboundLink.java:463) at com.ibm.ws.http.channel.inbound.impl.HttpInboundLink.handleNewRequest(HttpInboundLink.java:530) at com.ibm.ws.http.channel.inbound.impl.HttpInboundLink.processRequest(HttpInboundLink.java:316) at com.ibm.ws.http.channel.inbound.impl.HttpInboundLink.ready(HttpInboundLink.java:287) at com.ibm.ws.tcp.channel.impl.NewConnectionInitialReadCallback.sendToDiscriminators(NewConnectionInitialReadCallback.java:214) at com.ibm.ws.tcp.channel.impl.NewConnectionInitialReadCallback.complete(NewConnectionInitialReadCallback.java:113) at com.ibm.ws.tcp.channel.impl.AioReadCompletionListener.futureCompleted(AioReadCompletionListener.java:175) at com.ibm.io.async.AbstractAsyncFuture.invokeCallback(AbstractAsyncFuture.java:217) at com.ibm.io.async.AsyncChannelFuture$1.__AW_run(AsyncChannelFuture.java:205) at com.ibm.io.async.AsyncChannelFuture$1.run(AsyncChannelFuture.java) at com.ibm.ws.util.ThreadPool$Worker.run(ThreadPool.java:1892) Caused by: java.lang.NullPointerException at com.icbc.licensing.clio.action.VerificationAction.DbAuthInsertandCount(VerificationAction.java:118) at com.icbc.licensing.clio.action.VerificationAction.__AW_authenticateClient(VerificationAction.java:161) at com.icbc.licensing.clio.action.VerificationAction.authenticateClient(VerificationAction.java) at sun.reflect.GeneratedMethodAccessor440.invoke(Unknown Source) at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:56) at java.lang.reflect.Method.invoke(Method.java:620) at org.apache.el.parser.AstValue.__AW_invoke(AstValue.java:268) at org.apache.el.parser.AstValue.invoke(AstValue.java) at org.apache.el.MethodExpressionImpl.invoke(MethodExpressionImpl.java:278) at org.apache.myfaces.view.facelets.el.TagMethodExpression.invoke(TagMethodExpression.java:83) ... 46 more

Error Page Exception: Error Message: javax.servlet.ServletException: WebBeans context with scope type annotation @RequestScoped does not exist within current thread Error Code: 0 Target Servlet: Error Stack: javax.enterprise.context.ContextNotActiveException: WebBeans context with scope type annotation @RequestScoped does not exist within current thread at org.apache.webbeans.container.BeanManagerImpl.__AW_getContext(BeanManagerImpl.java:363) at org.apache.webbeans.container.BeanManagerImpl.getContext(BeanManagerImpl.java) at org.apache.webbeans.intercept.NormalScopedBeanInterceptorHandler.getContextualInstance(NormalScopedBeanInterceptorHandler.java:125) at org.apache.webbeans.intercept.NormalScopedBeanInterceptorHandler.invoke(NormalScopedBeanInterceptorHandler.java:96) at org.apache.webbeans.conversation.ConversationImpl_$$_javassist_0.isTransient(ConversationImpl_$$_javassist_0.java) at ...

s3696107y ago

verifcationAction.authenticateClient() call hit a null ref exception (called from the template at /verification.xhtml) and their error page is trying to use a webBean context which hasn't been setup or activated yet to display the error.

The original site of the null ref error seems to be the DBAuthInsert method at com.icbc.licensing.clio.action.VerificationAction.DbAuthInsertandCount(VerificationAction.java:118) so maybe a getConnection is returning a null and not being checked, or some config variable is borked. Would start digging at line 118 to work out what variables are being dereferenced and where their values come from.

emmelaich7y ago

This? https://stackoverflow.com/questions/25685895/webbeans-contex...

rad_gruchalski7y ago

The server process running in a thread other than the router? Dunno, I’m sure I could figure it out having access to the code. Support most likely does not employ software engineers / SREs.

j / k navigate · click thread line to collapse

0 comments

eitland7y ago

Wait wait wait.

Not so fast.

i'm one of those programmers who read manuals and stack traces but I have to admit that I've seen my share of both manuals as well as stack traces that didn't make much sense.

kickopotomus7y ago

lmkg7y ago

3 more replies

avhon17y ago

quaunaut7y ago

Functional programming not so much- languages like Elixir or JS used functionally don't have this problem generally.

1 more reply

dave_sid7y ago

Yeah I agree. The way this thread is going you would think that all errors are easy and all you have to do is what the computer tells you and you’re done. I wish I’d known it was all that simple!

TimTheTinker7y ago

> stack traces that didn't make much sense.

Those can be especially prevalent in systems that utilize a lot of indirection.

_mdpn7y ago

Especially when you end up in C++ template hell.

NeoBasilisk7y ago

That kind of stuff permanently damaged my ability to enjoy using C++.

samnardoni7y ago

Error in boost/bind.hpp:768

dba7dba7y ago

tyrex20177y ago

as in tensorflow stack traces

dsr_7y ago

And in the opposite direction: remember when you are writing error messages to include all the relevant details, and never ever write "this shouldn't happen" or "document later".

fhoodOP7y ago

What about, log_panic("If we have somehow managed to hit this code path, this project if FUBAR. I would recommend giving up and starting over.")

btschaegg7y ago

Somehow reminds me of Aliens:

  I say we take off and nuke the entire site from orbit. It's the only way to be sure.

:-)

m_samuel_l7y ago

That's annoying but fine as long as it's unique and you can grep it in the codebase.

1 more reply

pletnes7y ago

If used correctly, «this should not happen» can be very useful, indicating e.g that the program is in some illegal state, as opposed to the input being incorrectly formatted.

scarface747y ago

Even if that’s the case, create a custom exception and embed in the custom exception object the actual exception.

1 more reply

scarface747y ago

That’s only true if the developer of the class module let the entire stack trace get through to the consumer.

In C# it’s the difference between...

try

{

....

}catch(Exception e)

{

//Do stuff

   throw new MyCustomException(“Something Bad happened”);

}

And

try

{

....

}catch(Exception e)

{

  //do stuff

   throw;

}

moron4hire7y ago

Erh, exception types should include an inner exception parameter, for the generic one they wrap. So neither of your two examples are all that great.

scarface747y ago

Why would I wrap an exception if I don’t plan to have special handling? If it is exception that I didn’t throw because of a business reason, why not just throw the original exception?

1 more reply

debaserab27y ago

In what case would you ever want the second example?

orangepenguin7y ago

elsombrero7y ago

bmhin7y ago

avip7y ago

---

Error Page Exception SRVE0260E: The server cannot use the error page specified for your application to handle the Original Exception printed below.

s3696107y ago

emmelaich7y ago

This? https://stackoverflow.com/questions/25685895/webbeans-contex...

rad_gruchalski7y ago

The server process running in a thread other than the router? Dunno, I’m sure I could figure it out having access to the code. Support most likely does not employ software engineers / SREs.

j / k navigate · click thread line to collapse