Java limit stack trace

What is “-XX:-OmitStackTraceInFastThrow”

The “OmitStackTraceInFastThrow” was first introduced in JDK5. According to the release note of JDK5, the compiler in the server VM stops outputting the stack trace of the exceptions which have been thrown a few times. This is a one of optimizations which happens in C2 compile. And by adding “-XX:-OmitStackTraceInFastThrow”, we can disable this optimization.

According to the source code of OpenJDK, this optimization is applied to following exceptions

• NullPointerException
• ArithmeticException
• ArrayIndexOutOfBoundsException
• ArrayStoreException
• ClassCastException

Try It Out

java version "1.8.0_181" Java(TM) SE Runtime Environment (build 1.8.0_181-b13) Java HotSpot(TM) 64-Bit Server VM (build 25.181-b13, mixed mode)

public class TestOmitStackTraceInFastThrow < public static void main(String[] args) < int counter = 0; while(true) < try < Object obj = null; /* * If we cause the exception every time(= without this "if" statement), the optimization does not happen somehow. * So, cause it conditionally. */ if(counter % 2 == 0) < obj = new Object(); >// Cause NullpointerException obj.getClass(); >catch(NullPointerException e) < e.printStackTrace(); >counter++; > > >

I confirmed that the stack trace of NullPointerException disappeared by executing this code after a while without that JVM option. And by adding it, the stack trace never disappeared.

With other codes, I also confirmed that the stack trace of an exception out of that optimization (i.e. IllegalArgumentException) never disappeared.

Should We Use the Flag?

To make it easy to debug, I think we should use the the flag in local environment and staging environment. In production environment, I think basically we should use the flag. Of course if exceptions are thrown a lot of times and tons of stack trace are logged, the performance can be compromised. However, in that case, there is something wrong with the system and the clue for the problem is needed. So, if the application is not supposed to throw exceptions very often, we should use this flag even in production environment.

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I want full stacktrace and not . 25 more

posted 14 years ago

Hi,
How do I make jvm spit out everything and not shortening it to . 25 more?

Marshal

posted 14 years ago

posted 14 years ago

lowercase baba

posted 14 years ago

The way I read that API, sometimes the JVM may not give you the full stack trace. That implies to me it may not be possible. I don’t know this for a fact, but I’d have to question at this point WHY you need the full thing. Why doesn’t the first 5 or 10 give you enough information?

There are only two hard things in computer science: cache invalidation, naming things, and off-by-one errors

posted 14 years ago

they do not because it’s realy long path to the line with the problem. And in the middle there is reflection.

Marshal

posted 14 years ago

posted 14 years ago

I believe the «. N more» message generally occurs only when you have a second (or third, fourth, etc) exception which is the cause of the previous exception. The message means that the remaining N lines of the stack trace are exactly the same as the last N lines of the initial stack trace. So these lines don’t contain any new info. But if you really want to see that info again, you could re-copy the info from the previous exception.

posted 14 years ago

posted 14 years ago

Are you sure? How do you know, if you can’t actually see the complete stack trace?

Let me show you what I mean with an example:

If I run this from the command line, I get the following stack trace:

I’m saying that this means that the full stack trace would have been:

I just copied the last three lines of the first stack trace into the second stack trace. if you follow the line numbers carefully, they should make perfect sense. It’s just that the last three lines didn’t really add any new info that you couldn’t have figured out from the original stack trace, so printStackTrace() omitted them. The divergence in stack traces occurred within method c(), where the try/catch/rethrow occurred. But the callers of method c() were the same in each case.

So: you won’t see that the lines are duplicated, in the original stack trace — because the duplicated lines have already been omitted. But you can still figure out what they were.

If you still feel this explanation does not apply to your situation: can you show us the complete stack trace, including all «cuased by» nested exceptions? Plus the «. N more» message? That would help us figure out what you’re dealing with.

posted 14 years ago

Thanks a lot for trying to help unfortunatly I don’t think I am allowed to give you the stacktrace. And I DO get few caused by.
And I know it doesn’t repeat because it doesn’t lead me to exact line where exception happened. I follow the trace to get the initial problem but it just cuts. So all I know is in what method it happened. but not in what line

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What is a Java Stack Trace? How to Read & Analyze Traces

A Java stack trace is displayed when an error or exception occurs. The stack trace, also called a backtrace, consists of a collection of stack records, which store an application’s movement during its execution.

The stack trace includes information about program subroutines and can be used to debug or troubleshoot and is often used to create log files. These exceptions could be custom (defined by the user) or built-in. Examples include RuntimeException , NullPointerException , and ArrayIndexOutofBoundsException .

Now that you know what a stack trace is, let’s take a look at some examples, how to analyze stack traces, and how you can avoid a stack trace altogether with error handling.

Examples of Java Stack Traces

Example 1 — Temperature Conversion from Celsius to Fahrenheit

Let’s look at an example of converting temperatures from Celsius to Fahrenheit. Only an integer or float input is valid here. But if we try to provide another data type, such as a string, the compiler will throw an exception and print the stack trace.

 import java.util.Scanner; public class hello < public static void main(String[] args) < Scanner scanner = new Scanner(System.in); System.out.print("Enter value in Celsius to convert in fahrenheit:"); double Celsius = scanner.nextFloat(); double fahrenheit = (Celsius * 1.8)+32; System.out.printf("%.1f degrees Celsuis is %.1f degrees in Fahrenheit ",Celsius,fahrenheit); >>

When we run the above code and enter some invalid value, let’s say the string «hero,» we get the following output:

Enter value in Celsius to convert in fahrenheit: hero Exception in thread "main" java.util.InputMismatchException at java.base/java.util.Scanner.throwFor(Scanner.java:939) at java.base/java.util.Scanner.next(Scanner.java:1594) at java.base/java.util.Scanner.nextFloat(Scanner.java:2496) at com.example.myJavaProject.hello.main(hello.java:12)

Example 2 — Function Chaining

This is an example of function chaining, in which one function calls another in a chain-like fashion. Unlike in Example 1, no exception is thrown here, but the stack trace is explicitly printed using the dumpstack() method (a useful method when creating log files). This is good practice because we can use this code later for maintenance or to check the overall health or condition of the application.

public class Example < public static void main(String args[]) < f1(); >static void f1() < f2(); >static void f2() < f3(); >static void f3() < f4(); >static void f4() < Thread.dumpStack(); >>

When the above code is executed, we get the following output:

java.lang.Exception: Stack trace at java.base/java.lang.Thread.dumpStack(Thread.java:1380) at com.example.myJavaProject.Example.f4(Example.java:25) at com.example.myJavaProject.Example.f3(Example.java:20) at com.example.myJavaProject.Example.f2(Example.java:15) at com.example.myJavaProject.Example.f1(Example.java:10) at com.example.myJavaProject.Example.main(Example.java:6)

How to Read and Analyze Example 1’s Stack Trace

Let’s consider Example 1 for this analysis. Below is the breakdown of the output from its execution:

The first line in the stack trace:

The bottom line in the stack trace:

Now, let’s look at the entire stack trace and try to analyze it:

Enter value in Celsius to convert in fahrenheit: hero Exception in thread "main" java.util.InputMismatchException at java.base/java.util.Scanner.throwFor(Scanner.java:939) at java.base/java.util.Scanner.next(Scanner.java:1594) at java.base/java.util.Scanner.nextFloat(Scanner.java:2496) at com.example.myJavaProject.hello.main(hello.java:12)

The main() method is at the bottom of the stack because that is where the program began. By reading from bottom to top, we can now identify where and what exception is being raised. Tracing the source of this error back to the main() method reveals that an exception occurs when the user’s input is taken.

The second line from the top shows that the float input was taken using the function nextFloat() , which in turn calls the next() function, which in turn calls the throwFor() function. As a result, it throws an InputMismatchException .

How to Fix Example 1’s Code Using Error Handling and Stack Traces

Stack traces and exceptions are clearly related, as evidenced by the preceding examples. Stack traces can be avoided; in short, some common error handling techniques can be used to handle and resolve any exceptions thrown by the code during execution. The technique listed below can help avoid a stack trace.

Examine, Investigate, and Handle Java Errors

It’s common for amateur programmers to overlook exceptions in their code. Being able to examine, investigate, and handle mistakes can be very helpful prior to moving to the next step. Let’s handle the exception in Example 1 by using try and catch statements.

import java.util.Scanner; public class hello < public static void main(String[] args) < Scanner scanner = new Scanner(System.in); System.out.print("Enter value in Celsius to convert in fahrenheit:"); try < double Celsius = scanner.nextFloat(); double fahrenheit = (Celsius * 1.8) + 32; System.out.printf("%.1f degrees Celsuis is %.1f degrees in Fahrenheit ", Celsius, fahrenheit); >catch (InputMismatchException e) < System.out.println("Wrong input type entered. exiting the program"); >> >

In the above code, we have used a try — catch block to catch the exception and then print a custom message to notify the user to enter a valid input.

When the code above is executed, we get the following output:

Enter value in Celsius to convert in fahrenheit: hero
Wrong input type entered. exiting the program

Process finished with exit code 0

With the help of the try and catch blocks, the code to be tested is placed in the try block and any exception thrown by the code is handled in the catch block.

This is the most commonly used method to handle exceptions in Java and thus avoid stack traces.

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