Truncated stack trace

[Tim Bee]

Here is a question I was asked the other day. Maybe someone can answer it for me.

When you get a production abend, usually you get a full stack dump. Sometimes though, you only get the first line. What causes that?

[Carey Brown]

catch( Exception ex )
{
    System.err.println( ex.getMessage() ); // short one liner

    System.err.println( ex ); // Message plus some more info - one liner

    ex.printStackTrace(); // Message plus some more info
    // plus a number of lines of stack trace
}

[Tim Bee]

Carey Brown wrote:

catch( Exception ex )
{
    System.err.println( ex.getMessage() ); // short one liner

    System.err.println( ex ); // Message plus some more info - one liner

    ex.printStackTrace(); // Message plus some more info
    // plus a number of lines of stack trace
}

My understanding was that it was specifically about a production dump. Wouldn't this apply to any environment?

[Carey Brown]

Tim Bee wrote:My understanding was that it was specifically about a production dump. Wouldn't this apply to any environment?

I don't know what a "production dump" is. Not a part of the Java vernacular. Also, "abend" is not a Java term.

When exceptions are output the code designer can choose to output them any way they want, The three I listed are very typical.

[Junilu Lacar]

Carey Brown wrote:
I don't know what a "production dump" is. Not a part of the Java vernacular. Also, "abend" is not a Java term.

"production dump" - stack trace "dump" or listing - could also be referring to a core dump
"abend" - abnormal end - basically an exception that's not handled will cause a program to abend

I don't know what would cause just one line from a full production dump to be visible. What comes after the 1 line? Nothing? or is there something else?

[Carey Brown]

Junilu Lacar wrote:"production dump" - stack trace "dump" or listing - could also be referring to a core dump
"abend" - abnormal end - basically an exception that's not handled will cause a program to abend

I don't know what would cause just one line from a full production dump to be visible. What comes after the 1 line? Nothing? or is there something else?

So, are we talking about a case where the JVM itself has crashed?

[Junilu Lacar]

Carey Brown wrote:
So, are we talking about a case where the JVM itself has crashed?

I'm not too clear on that either, I just know that abend is a term that's used on bigger iron hardware platforms, e.g., mainframes running UNIX and such.

[J. Kevin Robbins]

Junilu Lacar wrote:

Carey Brown wrote:
So, are we talking about a case where the JVM itself has crashed?

I'm not too clear on that either, I just know that abend is a term that's used on bigger iron hardware platforms, e.g., mainframes running UNIX and such.

That's what it sounds like. I worked at a place than ran Websphere on AIX <shudder>. JVM crashes were a regular problem and they always referred to a core dump for analysis. They can be very difficult to analyze. I think there are third-party tools designed just for that purpose. But why OP is getting just one line is a mystery to me.

[Junilu Lacar]

J. Kevin Robbins wrote:I worked at a place than ran Websphere on AIX <shudder>. JVM crashes were a regular problem and they always referred to a core dump for analysis.

Yup, so did I. My wife still works there. It's one Ohio's biggest employers with about 10K people in just one building alone. No kidding. The building has as much floor area as the Empire State Building. If you want to see it on Google Maps, go to the northern part of the I-270 loop in Columbus, OH and look for the Polaris Mall, which is right across the street from it.

Anyway, the only thing that comes to mind is that the JVM crashes so badly that it doesn't even have time to finish printing out the stack trace before it dies. Maybe a buffer of some sort didn't get flushed prior to the JVM crashing. These are ust WAGs really (Wild-A$$ Guesses)

[Tim Bee]

Just to clarify, I was asked this in an interview and I told him I had never seen it before. I have no idea what he was talking about but he said that if I knew Java, then I should know this.

[J. Kevin Robbins]

Tim Bee wrote:Just to clarify, I was asked this in an interview and I told him I had never seen it before. I have no idea what he was talking about but he said that if I knew Java, then I should know this.

Interviewers that ask questions like this should be dragged into the street and severely beaten. You've just heard from several very experienced developers and we all agree that we've never seen or heard of such a thing.

And it's more of a server administration question than a development question. It's extremely rare to have to analyze a memory dump. Most developers will probably work their entire careers and never need to do so.

[fred rosenberger]

many *nix flavors give you the option to limit a core dump file size. I could see an argument for cranking it down to almost nil on a prod machine so you don't fill your disk with junk.

[Junilu Lacar]

Tim Bee wrote:Just to clarify, I was asked this in an interview and I told him I had never seen it before. I have no idea what he was talking about but he said that if I knew Java, then I should know this.

I would have been sorely tempted to say "Well, if you guys knew how to program in Java, then you'd never have a need to know this." I would walk away from that interview, honestly; I'm too old for that kind of cr*p.

Besides, if I stayed too long, I might also be tempted to do what J. Kevin said should be done ... I actually do have that very particular set of skillz...

[Tim Bee]

Junilu Lacar wrote:

Tim Bee wrote:Just to clarify, I was asked this in an interview and I told him I had never seen it before. I have no idea what he was talking about but he said that if I knew Java, then I should know this.

I would have been sorely tempted to say "Well, if you guys knew how to program in Java, then you'd never have a need to know this." I would walk away from that interview, honestly; I'm too old for that kind of cr*p.

Besides, if I stayed too long, I might also be tempted to do what J. Kevin said should be done ... I actually do have that very particular set of skillz...

Problem is, these companies are having their senior programmers interview because the managers no longer know the technology. How does a programmer know what to ask? Some do but many don't.
I have been interviewed more than once from somebody in India and I am in Toronto.

[Paul Clapham]

Tim Bee wrote:Just to clarify, I was asked this in an interview and I told him I had never seen it before. I have no idea what he was talking about but he said that if I knew Java, then I should know this.

Are you kidding? I worked as a Java programmer for about 10 years and I never had to look at a core dump. Only once do I recall such a thing happening, and I think all I did was to paste the relevant part of it into the request I sent to IBM.

And I recognize the word "abend", but that was a jargon word used by mainframe programmers; there's very little overlap between the mainframe world and the Java world.

[Junilu Lacar]

Tim Bee wrote:I have been interviewed more than once from somebody in India and I am in Toronto.

If you don't get hired by these guys, I would say that you have received a big blessing in disguise; someone out there is looking out for your best interests.

EDIT: Let me clarify that before someone takes it the wrong way. Anyone who asks those kinds of questions is probably not going to really know how to write good programs. They are asking about the wrong thing. It's like asking someone to analyze the patterns of leaves in your driveway to figure out what's wrong with your car when it crashes into your porch.

As Paul implied, you shouldn't ever have to give a rat's @ss about abend except to know that it indicates something is seriously screwed up with either your runtime environment or in your Java application. If there's a problem in your Java program, you should have the sense enough to be able to write Java code to handle that problem and give you an indication of how to find it and fix it. Last resort is to copy the core dump and punt it to the vendor's technical support guys.

If you're in Toronto and the person interviewing you halfway around the world, then that would indicate to me that the team has a bit of dysfunction. At the very least, the lines of communication on that team are very tenuous. That's not going to be a successful team or one that's going to be fun to work on.

[Junilu Lacar]

Tim Bee wrote:Problem is, these companies are having their senior programmers interview because the managers no longer know the technology. How does a programmer know what to ask? Some do but many don't.

Uhhmm...

If anything, I would expect the senior programmers to be the ones who have the final say on who to hire onto their teams. If they don't know what questions to ask, they have no business being in the role of "senior programmer", IMO.

Again, count it as a blessing in disguise if they don't hire you. Life is too short to have to work with those kind of developers.